Human Heart – Diagram and Anatomy of the Heart

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Continued From Above…
pulmonary arteries and veins, and the vena cava. The inferior tip of the heart, known as the apex, rests just superior to the diaphragm. The base of the heart is located along the body’s midline with the apex pointing toward the left side. Because the heart points to the left, about 2/3 of the heart’s mass is found on the left side of the body and the other 1/3 is on the right.

Anatomy of the Heart

Pericardium

The heart sits within a fluid-filled cavity called the pericardial cavity. The walls and lining of the pericardial cavity are a special membrane known as the pericardium. Pericardium is a type of serous membrane that produces serous fluid to lubricate the heart and prevent friction between the ever beating heart and its surrounding organs. Besides lubrication, the pericardium serves to hold the heart in position and maintain a hollow space for the heart to expand into when it is full. The pericardium has 2 layers—a visceral layer that covers the outside of the heart and a parietal layer that forms a sac around the outside of the pericardial cavity.

Structure of the Heart Wall

The heart wall is made of 3 layers: epicardium, myocardium and endocardium.

• Epicardium. The epicardium is the outermost layer of the heart wall and is just another name for the visceral layer of the pericardium. Thus, the epicardium is a thin layer of serous membrane that helps to lubricate and protect the outside of the heart. Below the epicardium is the second, thicker layer of the heart wall: the myocardium.
• Myocardium. The myocardium is the muscular middle layer of the heart wall that contains the cardiac muscle tissue. Myocardium makes up the majority of the thickness and mass of the heart wall and is the part of the heart responsible for pumping blood. Below the myocardium is the thin endocardium layer.
• Endocardium. Endocardium is the simple squamous endothelium layer that lines the inside of the heart. The endocardium is very smooth and is responsible for keeping blood from sticking to the inside of the heart and forming potentially deadly blood clots.

The thickness of the heart wall varies in different parts of the heart. The atria of the heart have a very thin myocardium because they do not need to pump blood very far—only to the nearby ventricles. The ventricles, on the other hand, have a very thick myocardium to pump blood to the lungs or throughout the entire body. The right side of the heart has less myocardium in its walls than the left side because the left side has to pump blood through the entire body while the right side only has to pump to the lungs.

Chambers of the Heart

The heart contains 4 chambers: the right atrium, left atrium, right ventricle, and left ventricle. The atria are smaller than the ventricles and have thinner, less muscular walls than the ventricles. The atria act as receiving chambers for blood, so they are connected to the veins that carry blood to the heart. The ventricles are the larger, stronger pumping chambers that send blood out of the heart. The ventricles are connected to the arteries that carry blood away from the heart.

The chambers on the right side of the heart are smaller and have less myocardium in their heart wall when compared to the left side of the heart. This difference in size between the sides of the heart is related to their functions and the size of the 2 circulatory loops. The right side of the heart maintains pulmonary circulation to the nearby lungs while the left side of the heart pumps blood all the way to the extremities of the body in the systemic circulatory loop.

Valves of the Heart

The heart functions by pumping blood both to the lungs and to the systems of the body. To prevent blood from flowing backwards or “regurgitating” back into the heart, a system of one-way valves are present in the heart. The heart valves can be broken down into two types: atrioventricular and semilunar valves.

• Atrioventricular valves. The atrioventricular (AV) valves are located in the middle of the heart between the atria and ventricles and only allow blood to flow from the atria into the ventricles. The AV valve on the right side of the heart is called the tricuspid valve because it is made of three cusps (flaps) that separate to allow blood to pass through and connect to block regurgitation of blood. The AV valve on the left side of the heart is called the mitral valve or the bicuspid valve because it has two cusps. The AV valves are attached on the ventricular side to tough strings called chordae tendineae. The chordae tendineae pull on the AV valves to keep them from folding backwards and allowing blood to regurgitate past them. During the contraction of the ventricles, the AV valves look like domed parachutes with the chordae tendineae acting as the ropes holding the parachutes taut.
• Semilunar valves. The semilunar valves, so named for the crescent moon shape of their cusps, are located between the ventricles and the arteries that carry blood away from the heart. The semilunar valve on the right side of the heart is the pulmonary valve, so named because it prevents the backflow of blood from the pulmonary trunk into the right ventricle. The semilunar valve on the left side of the heart is the aortic valve, named for the fact that it prevents the aorta from regurgitating blood back into the left ventricle. The semilunar valves are smaller than the AV valves and do not have chordae tendineae to hold them in place. Instead, the cusps of the semilunar valves are cup shaped to catch regurgitating blood and use the blood’s pressure to snap shut.

Conduction System of the Heart

The heart is able to both set its own rhythm and to conduct the signals necessary to maintain and coordinate this rhythm throughout its structures. About 1% of the cardiac muscle cells in the heart are responsible for forming the conduction system that sets the pace for the rest of the cardiac muscle cells.

The conduction system starts with the pacemaker of the heart—a small bundle of cells known as the sinoatrial (SA) node. The SA node is located in the wall of the right atrium inferior to the superior vena cava. The SA node is responsible for setting the pace of the heart as a whole and directly signals the atria to contract. The signal from the SA node is picked up by another mass of conductive tissue known as the atrioventricular (AV) node.

The AV node is located in the right atrium in the inferior portion of the interatrial septum. The AV node picks up the signal sent by the SA node and transmits it through the atrioventricular (AV) bundle. The AV bundle is a strand of conductive tissue that runs through the interatrial septum and into the interventricular septum. The AV bundle splits into left and right branches in the interventricular septum and continues running through the septum until they reach the apex of the heart. Branching off from the left and right bundle branches are many Purkinje fibers that carry the signal to the walls of the ventricles, stimulating the cardiac muscle cells to contract in a coordinated manner to efficiently pump blood out of the heart.

Physiology of the Heart

Coronary Systole and Diastole

At any given time the chambers of the heart may found in one of two states:

• Systole. During systole, cardiac muscle tissue is contracting to push blood out of the chamber.
• Diastole. During diastole, the cardiac muscle cells relax to allow the chamber to fill with blood. Blood pressure increases in the major arteries during ventricular systole and decreases during ventricular diastole. This leads to the 2 numbers associated with blood pressure—systolic blood pressure is the higher number and diastolic blood pressure is the lower number. For example, a blood pressure of 120/80 describes the systolic pressure (120) and the diastolic pressure (80).

The Cardiac Cycle

The cardiac cycle includes all of the events that take place during one heartbeat. There are 3 phases to the cardiac cycle: atrial systole, ventricular systole, and relaxation.

• Atrial systole: During the atrial systole phase of the cardiac cycle, the atria contract and push blood into the ventricles. To facilitate this filling, the AV valves stay open and the semilunar valves stay closed to keep arterial blood from re-entering the heart. The atria are much smaller than the ventricles, so they only fill about 25% of the ventricles during this phase. The ventricles remain in diastole during this phase.
• Ventricular systole: During ventricular systole, the ventricles contract to push blood into the aorta and pulmonary trunk. The pressure of the ventricles forces the semilunar valves to open and the AV valves to close. This arrangement of valves allows for blood flow from the ventricles into the arteries. The cardiac muscles of the atria repolarize and enter the state of diastole during this phase.
• Relaxation phase: During the relaxation phase, all 4 chambers of the heart are in diastole as blood pours into the heart from the veins. The ventricles fill to about 75% capacity during this phase and will be completely filled only after the atria enter systole. The cardiac muscle cells of the ventricles repolarize during this phase to prepare for the next round of depolarization and contraction. During this phase, the AV valves open to allow blood to flow freely into the ventricles while the semilunar valves close to prevent the regurgitation of blood from the great arteries into the ventricles.

Blood Flow through the Heart

Deoxygenated blood returning from the body first enters the heart from the superior and inferior vena cava. The blood enters the right atrium and is pumped through the tricuspid valve into the right ventricle. From the right ventricle, the blood is pumped through the pulmonary semilunar valve into the pulmonary trunk.

The pulmonary trunk carries blood to the lungs where it releases carbon dioxide and absorbs oxygen. The blood in the lungs returns to the heart through the pulmonary veins. From the pulmonary veins, blood enters the heart again in the left atrium.

The left atrium contracts to pump blood through the bicuspid (mitral) valve into the left ventricle. The left ventricle pumps blood through the aortic semilunar valve into the aorta. From the aorta, blood enters into systemic circulation throughout the body tissues until it returns to the heart via the vena cava and the cycle repeats.

The Electrocardiogram

The electrocardiogram (also known as an EKG or ECG) is a non-invasive device that measures and monitors the electrical activity of the heart through the skin. The EKG produces a distinctive waveform in response to the electrical changes taking place within the heart.

The first part of the wave, called the P wave, is a small increase in voltage of about 0.1 mV that corresponds to the depolarization of the atria during atrial systole. The next part of the EKG wave is the QRS complex which features a small drop in voltage (Q) a large voltage peak (R) and another small drop in voltage (S). The QRS complex corresponds to the depolarization of the ventricles during ventricular systole. The atria also repolarize during the QRS complex, but have almost no effect on the EKG because they are so much smaller than the ventricles.

The final part of the EKG wave is the T wave, a small peak that follows the QRS complex. The T wave represents the ventricular repolarization during the relaxation phase of the cardiac cycle. Variations in the waveform and distance between the waves of the EKG can be used clinically to diagnose the effects of heart attacks, congenital heart problems, and electrolyte imbalances.

Heart Sounds

The sounds of a normal heartbeat are known as “lubb” and “dupp” and are caused by blood pushing on the valves of the heart. The “lubb” sound comes first in the heartbeat and is the longer of the two heart sounds. The “lubb” sound is produced by the closing of the AV valves at the beginning of ventricular systole. The shorter, sharper “dupp” sound is similarly caused by the closing of the semilunar valves at the end of ventricular systole. During a normal heartbeat, these sounds repeat in a regular pattern of lubb-dupp-pause. Any additional sounds such as liquid rushing or gurgling indicate a structure problem in the heart. The most likely causes of these extraneous sounds are defects in the atrial or ventricular septum or leakage in the valves.

Cardiac Output

Cardiac output (CO) is the volume of blood being pumped by the heart in one minute. The equation used to find cardiac output is: CO = Stroke Volume x Heart Rate

Stroke volume is the amount of blood pumped into the aorta during each ventricular systole, usually measured in milliliters. Heart rate is the number of heartbeats per minute. The average heart can push around 5 to 5.5 liters per minute at rest.

Heart Health Problems

Heart disease is very common, disrupting the normal function of this important organ and often causing death. Visit our Diseases and Conditions section to learn more about common cardiovascular diseases and how we can prevent them. For information about your personal hereditary risks of a variety of conditions involving the heart (such as those arising from hemochromatosis or G6PDD, to name two very common hereditary disorders), learn more about DNA health testing.

real heart pictures labeled

It is this rhythmic movement between the heart and arteries which result in an efficient circulation system. 4. Anatomy of the Heart. If one of your organs is working that hard, it makes sense to learn about how it functions! 6. 149 151 20. Check out our collection of well-curated heart and love images for you to download. These are two large veins carrying deoxygenated blood from the body to the heart. 97 153 19. They work non-stop since birth till death. The heart is the epicenter of the circulatory system, which supplies the body with oxygen and other important nutrients needed to sustain life. Explore body systems related to the heart for a greater overview of how the body functions. This website uses cookies to improve your experience. Learn vocabulary, terms, and more with flashcards, games, and other study tools. 81 123 14. You can refer to your textbook in order to label the: Aorta; Superior vena cava; Inferior vena cava; Right and left atria; Right and left ventricles; Pulmonary veins and … Explore {{searchView.params.phrase}} by colour family The walls and lining of the pericardial cavity are a special membrane known as the pericardium. Family Health Heart. Heart Human Heart. Its contraction and relaxation leads to the heartbeat, we all are familiar with. heart bypass surgery stock pictures, royalty-free photos & images . … Oct 6, 2016 – Images and video to teach children and adults about the basics of heart and vascular anatomy. Arteries take oxygenated blood away from the heart, except the pulmonary artery, that takes deoxygenated blood to the lungs for oxygenation. English French German Latin Spanish View all. The right ventricle is the chamber within the heart that is responsible for … Anatomy of the Heart Pericardium. Images are labelled, providing an invaluable medical and anatomical tool. Science. Label and color the pulmonary artery sky blue. The heart has a double-pump feature that transports blood away from it and back to it. The heart features four types of valves which regulate the flow of blood through the heart. The left atrium contracts to pump the oxygenated blood it received from the pulmonary vein into the left ventricle. Try these … 1818 1523 333. NEW. cardiologist and medical concept – human heart stock pictures, royalty-free photos & images heart icon in flat style isolated illustration on white transparent background – human heart stock pictures, royalty-free photos & images The human heart resembles the shape of an upside-down pear, weighing between 7-15 ounces, and is little larger than the size of the fist. Arts and Humanities . Download Human body anatomy stock photos. The average human heart weighs between 6 and 11 ounces. Usually arteries are characterized with the transport of oxygenated blood, however, the pulmonary artery is an exception. Browse. Out of these cookies, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. Wedding Icons. Together, these arteries supply oxygen-rich blood to the atria and ventricles of the heart. The … Newborn Feet Hands. These valves have been clearly shown in the labeled diagram of the heart. 3. Cardiac muscles require constant supply of oxygen and lack of it causes damage. 1380 1184 224. This will reset incorrect answers only. The heart is situated at the centre of the chest and points slightly towards the left. Art History Dance Film and TV Music Theater … The right ventricle pumps deoxygenated blood, which it receives from the right atria, into the pulmonary artery, which takes it to the lungs. See human heart anatomy stock video clips. 116 119 14. This model has the real size of a person’s heart and is used in high school for education to learn pupils or teenagers about biology and science. Veins are like arteries, however, are not as strong as arteries as they do not have to transport blood at high pressure. Arteries are blood vessels that transport oxygen-rich blood to the capillaries, where actual exchange of carbon dioxide and oxygen takes place. Take the following quiz to know how much you know about your beloved a.k.a life saver heart. 954 995 132. The inferior vena cava on the other hand collects blood from the parts of the body located below the heart into the right atrium. The different parts of heart in heart diagram are discussed below:. When you … The pulmonary artery divides into the right and left branch, which take the blood to the right and left lung respectively. If you want to redo an answer, click on the box and the answer will go back to the top so you can move it to another box. love romantic nature flowers sad couple happy woman health dark beautiful earth broken heart green close-up texture music garden hearts flower alone background roses girl baby romance heart health summer night wedding Daria … The right ventricle is one of…, The heart is a hollow, muscular organ composed of cardiac muscles and connective tissue that acts as a pump to distribute blood throughout the body’s…, The right atrium is one of the four chambers of the heart. 5. On average, the heart beats about 100,000 times a day, i.e., around 3 billion beats in a lifetime. The heart has three layers. The image is available for download in high resolution quality up to 6000×6000. 7. Free for commercial use High Quality Images The human heart and its functions are truly fascinating. of 129. left ventricle muscle outline of the anatomy cardiovascular aortic heart part heart human anatomy human heart with parts human heart anatomy vector anatomy of the heart heart anatomy vector diagram of the heart. The wall of the heart can be divided into three layers; outer epicardium, inner endocardium and middle myocardium. The septum separates the ventricles from each other. Start studying Heart Anatomy w/ Pictures. A Labeled Diagram of the Human Heart You Really Need to See. The coronary arteries are attached to the heart and supply oxygenated blood to the heart muscles. The heart, one of the most significant organs in the human body, is nothing but a muscular pump which pumps blood throughout the body. The myocardium, which consists of the cardiac muscle tissues, is responsible for the contraction of heart chambers for pumping of blood. Ventricles have thicker walls than the atria, because they need to pump blood to the body. Within the mediastinum, the heart is separated … human heart anatomy images. Browse 17,629 human heart stock photos and images available or search for human heart illustration or human heart vector to find more great stock photos and pictures. Rose Flowers Roses. Find free pictures, photos, diagrams, images and information related to the human body right here at Science Kids. : You are free: to share – to copy, distribute and transmit the work; to remix – to adapt the work; Under the following conditions: attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. 2037 1686 358. 71 76 36. Huge collection, amazing choice, 100+ million high quality, affordable RF and RM images. Arteries are smooth on the inside and tough on the outside. The average male heart weighs around 280 to 340 grams (10 to 12 ounces). The muscle is strong enough to pump up to 2,000 gallons — as much as a fire department’s tanker truck — of blood through one’s body every day. The pumped blood also removes waste products from the body. 45 60 4. This science quiz game will help you identify the parts of the human heart with ease. Biology Chemistry Earth Science Physics Space Science View all. Daisy Heart Flowers. This category only includes cookies that ensures basic functionalities and security features of the website. 1180 962 194. This type of muscle is found only in the heart and the unique feature about these muscles is that they never tire out. Label and color the left … The left ventricle is the strongest and largest chamber in the heart. The heart, one of the most significant organs in the human body, is nothing but a muscular pump which pumps blood throughout the body. Last medically reviewed on March 10, 2015, The coronary sinus is a collection of smaller veins that merge together to form the sinus (or large vessel), which is located along the heart’s…, The left atrium is one of the four chambers of the heart, located on the left posterior side. This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license. 78 91 7. When the heart relaxes, contraction of the arteries takes place, which exert enough force to push the blood along the blood vessels. Freshly oxygenated blood leaves the left side of the heart through the ascending aorta—the largest artery in the human body. Figure 1 shows the position of the heart within the thoracic cavity. If you’re trying to identify parts of the heart for a class you’re taking, it’s good practice to draw the heart yourself and label each segment. This hollow muscular organ pumps blood via a well-organized network of blood vessels. The heart pumps around 5.7 litres of blood in a day throughout the body. These cookies will be stored in your browser only with your consent. red balloons in the sky . Our website services, content, and products are for informational purposes only. See diagram of the human heart stock video clips. The human heart, comprises four chambers: right atrium, left atrium, right ventricle and left ventricle. Balloon Heart Love. The Heart – Science Quiz: Day after day, your heart beats about 100,000 times, pumping 2,000 gallons of blood through 60,000 miles of blood vessels. Label and color the inferior vena cava blue. Romantic Heart Pictures . The two upper chambers are called the left and the right atria, and the two lower chambers are known as the left and the right ventricles. It comprises valves which allow the blood to flow only in one direction. Sign up to receive the latest and greatest articles from our site automatically each week (give or take)…right to your inbox. SKELETAL. The heart is comprised of two atria and two ventricles. Its primary roles are to act as a holding chamber for…, The right ventricle is the chamber within the heart that is responsible for pumping oxygen-depleted blood to the lungs. It is located in the bottom left portion of the heart below the left atrium, separated by the…, Combined with the cardiovascular system, the circulatory system helps to fight off disease, helps the body maintain a normal body temperature, and…, Humans are sexual, meaning that both a male and a female are needed to reproduce. The heart is the body’s engine room, responsible for pumping life-sustaining blood via a 60,000-mile-long (97,000-kilometer-long) network of vessels. Heart Blood Organ. add to cart. Blood comes in through veins and exists via arteries—to … Affordable and search from millions of royalty free images, photos and vectors. Find the perfect heart and arteries stock photo. After the exchange of carbon dioxide and oxygen takes place between the arteries and capillaries, the blood containing waste products is received by the veins. Heart diagram for kids can be printed out and colored, to make it easier to understand. The heart, though small in size, performs highly significant functions that sustains human life. Have a look at our broad collection of heart pictures and download your images for free! See more ideas about heart anatomy, anatomy, anatomy and physiology. Pericardium is a type of serous membrane that produces serous fluid to lubricate the heart and prevent friction between the ever beating heart and its surrounding organs. Create. The heart is the muscle into the lower half of the image of human heart diagram.The heart has four chambers and the right left atria are shown in purple color into heart … The blood pumped by the heart not only provides nutrients to the body cells, but also removes the waste materials from different parts of the body. Label and color the right ventricle brown. Label and color the superior vena cava blue. Photo name: Human Heart Diagram Picture category: Human Body Image size: 70 KB Dimensions: 600 x 600 Photo description: This is an excellent human heart diagram which uses different colors to show different parts and also labels a number of important heart … Also referred to as bicuspid valve or left atrioventricular valve, the mitral valve has two cusps. The average heart beats between 60 and 90 times per minute, but this depends on a person’s cardiovascular health and activity level. It is cone-shaped, with the point of the cone pointing down to the left. It pumps the blood it receives into the right ventricle. © 2005-2021 Healthline Media a Red Ventures Company. 66 84 10. Anatomy of the human heart and coronaries: how to visualize anatomic structures . VENOUS. The pulmonary valve separates the right ventricle from the left pulmonary artery. This valve separates the left ventricle from the left atrium. Explore {{searchView.params.phrase}} by colour family Download Real heart stock photos. Cell Cell Division. The network of blood vessels in the human body is such that it connects all the organs of the body to the heart. The human heart and its functions are truly fascinating. The human heart is one hell of a vital organ for every human. The more physically fit people are, the lower their resting heart rates will be. Human Heart Anatomy Human Heart Anatomy Illustration. This main artery branches into several smaller arteries, which then supply fresh oxygenated blood to the body. Languages. They permit blood flow in one direction only, and prevent backflow of blood. If the coronary arteries bring oxygen-rich blood to the heart chambers, the coronary sinus collects deoxygenated blood from the heart muscles and takes it to the right atria, along with the venae cavae. But opting out of some of these cookies may have an effect on your browsing experience. Cast from a real human heart and didactically prepared to facilitate a better understanding of the anatomy and blood flow of the heart. The heart, though small in size, performs highly significant functions that sustains human life. Since it only pumps blood into the next chamber of the heart (right ventricle), its walls are not too thick. In order to understand how that happens, it is necessary to understand the anatomy and physiology of the heart. The more healthy your heart is, the longer the chances you have of surviving, so you better take care of it. As the left atrium contracts, the mitral valve opens and closes when the left atrium relaxes, thereby preventing backflow of blood. All rights reserved. The heart sits within a fluid-filled cavity called the pericardial cavity. Related Images: love romantic romance valentine’s. 6789 Quail Hill Pkwy, Suite 211 Irvine CA 92603. The main function of the blood vessels is to transport oxygenated blood from the heart to the rest of the body (via the lungs), and collect deoxygenated blood from the different organs and take it to the heart for oxygenation (which takes place in the lungs). It is mandatory to procure user consent prior to running these cookies on your website. Log in Sign up. In this interactive, you can label parts of the human heart. The two atria and ventricles are separated from each other by a muscle wall called ‘septum’. Our site includes quite a bit of content, so if you’re having an issue finding what you’re looking for, go on ahead and use that search feature there! As the right ventricle contracts, the valves open and blood flows into the left pulmonary artery. Drag and drop the text labels onto the boxes next to the heart diagram. Heart Love Romance. Label and color the left atrium orange. 3B Smart Anatomy 5 year warranty Life-Size Human Heart Model, 5 parts – 3B Smart Anatomy. Observing a diagram of the heart, as the one here, will help comprehend the different parts of the human heart. Jun 29, 2017 – Human Heart Labeled Diagram The Human Heart Diagram Labeled – Human Anatomy photo, Human Heart Labeled Diagram The Human Heart Diagram Labeled – Human Anatomy image, Human Heart Labeled Diagram The Human Heart Diagram Labeled – Human Anatomy gallery It shows the cardiac … more. Isolate or highlight the path, … Hearts are the symbol of love! Also referred to as the atrioventricular valve, the tricuspid valve allows blood to flow from the right atrium into the right ventricle, and prevents backflow of the same. Below is an image of the outside of a normal, healthy human heart diagram.. Heart … When the heart beats, the arteries expand and get filled with blood. Label and color the right atrium violet. Well, we’re looking for good writers who want to spread the word. The four types of valves are: The tricuspid valve separates the right atrium from the right ventricle, and regulates the blood flow between them. It carries oxygenated blood from the lungs to the left side of the heart. 49 65 4. The normal heart is about the size of a closed fist, and weighs about 10.5 ounces. 2. WebMD’s Heart Anatomy Page provides a detailed image of the heart and provides information on heart conditions, tests, and treatments. Surgery assistant perfusionist operating a modern heart lung machine Surgery assistant perfusionist operating a modern heart lung machine with artificial cardiac valve at … Their muscular wall helps the heart to pump blood. Copyright © Bodytomy & Buzzle.com, Inc. The heart wall consists of three layers: Epicardium: The outer layer of the wall of … The involuntary, striated heart muscles control the contraction and relaxation of the heart chambers, and the pumping of blood. The way the heart functions is really remarkable. Photo “Real Heart Shinning in Light – Human Anatomy model” can be used for personal and commercial purposes according to the conditions of the purchased Royalty-free license. The test mode allows instant evaluation of user progress. The above labeled diagram can be modified as per your requirements for kids. The exterior of heart in human heart diagram. If you want to check your answers, use the Reset Incorrect button. 97 105 19. Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies. The aortic valve separates the left ventricle from the aorta, and controls the blood flow from the ventricle into the rest of the body. white and yellow daisies. Woman Female Girl. Right ventricle. LUNGS. It is a soft, spongy tissue that surrounds the…. Location of the Heart . All four branches pour oxygenated blood into the left atrium of the heart. Search. Veins are generally characterized as blood vessels carrying deoxygenated blood to the lungs, however, the pulmonary vein is an exception. Would you like to write for us? Set the heart rate to simulate real scenarios, or control the animation to examine every minute movement.-60 BEATS PER MINUTE + SYSTEMS . The right atria receives deoxygenated blood from the venae cavae (superior and inferior) and from the heart muscle (coronary sinus). Trace an artery back to its origin at the heart. 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heart with labels | Anatomy System

Human Body Anatomy Diagrams

Heart Anatomy | Anatomy and Physiology II

Learning Objectives

By the end of this section, you will be able to:

• Describe the location and position of the heart within the body cavity
• Describe the internal and external anatomy of the heart
• Identify the tissue layers of the heart
• Relate the structure of the heart to its function as a pump
• Compare systemic circulation to pulmonary circulation
• Identify the veins and arteries of the coronary circulation system
• Trace the pathway of oxygenated and deoxygenated blood thorough the chambers of the heart

The vital importance of the heart is obvious. If one assumes an average rate of contraction of 75 contractions per minute, a human heart would contract approximately 108,000 times in one day, more than 39 million times in one year, and nearly 3 billion times during a 75-year lifespan. Each of the major pumping chambers of the heart ejects approximately 70 mL blood per contraction in a resting adult. This would be equal to 5.25 liters of fluid per minute and approximately 14,000 liters per day. Over one year, that would equal 10,000,000 liters or 2.6 million gallons of blood sent through roughly 60,000 miles of vessels. In order to understand how that happens, it is necessary to understand the anatomy and physiology of the heart.

Location of the Heart

The human heart is located within the thoracic cavity, medially between the lungs in the space known as the mediastinum. Figure 1 shows the position of the heart within the thoracic cavity. Within the mediastinum, the heart is separated from the other mediastinal structures by a tough membrane known as the pericardium, or pericardial sac, and sits in its own space called the pericardial cavity. The dorsal surface of the heart lies near the bodies of the vertebrae, and its anterior surface sits deep to the sternum and costal cartilages. The great veins, the superior and inferior venae cavae, and the great arteries, the aorta and pulmonary trunk, are attached to the superior surface of the heart, called the base. The base of the heart is located at the level of the third costal cartilage, as seen in Figure 1. The inferior tip of the heart, the apex, lies just to the left of the sternum between the junction of the fourth and fifth ribs near their articulation with the costal cartilages. The right side of the heart is deflected anteriorly, and the left side is deflected posteriorly. It is important to remember the position and orientation of the heart when placing a stethoscope on the chest of a patient and listening for heart sounds, and also when looking at images taken from a midsagittal perspective. The slight deviation of the apex to the left is reflected in a depression in the medial surface of the inferior lobe of the left lung, called the cardiac notch.

Figure 1. The heart is located within the thoracic cavity, medially between the lungs in the mediastinum. It is about the size of a fist, is broad at the top, and tapers toward the base.

Everyday Connection: 

CPR

The position of the heart in the torso between the vertebrae and sternum (see the image above for the position of the heart within the thorax) allows for individuals to apply an emergency technique known as cardiopulmonary resuscitation (CPR) if the heart of a patient should stop. By applying pressure with the flat portion of one hand on the sternum in the area between the lines in the image below), it is possible to manually compress the blood within the heart enough to push some of the blood within it into the pulmonary and systemic circuits. This is particularly critical for the brain, as irreversible damage and death of neurons occur within minutes of loss of blood flow. Current standards call for compression of the chest at least 5 cm deep and at a rate of 100 compressions per minute, a rate equal to the beat in “Staying Alive,” recorded in 1977 by the Bee Gees. If you are unfamiliar with this song, you can likely find a version of it online. At this stage, the emphasis is on performing high-quality chest compressions, rather than providing artificial respiration. CPR is generally performed until the patient regains spontaneous contraction or is declared dead by an experienced healthcare professional.

When performed by untrained or overzealous individuals, CPR can result in broken ribs or a broken sternum, and can inflict additional severe damage on the patient. It is also possible, if the hands are placed too low on the sternum, to manually drive the xiphoid process into the liver, a consequence that may prove fatal for the patient. Proper training is essential. This proven life-sustaining technique is so valuable that virtually all medical personnel as well as concerned members of the public should be certified and routinely recertified in its application. CPR courses are offered at a variety of locations, including colleges, hospitals, the American Red Cross, and some commercial companies. They normally include practice of the compression technique on a mannequin.

Figure 2. If the heart should stop, CPR can maintain the flow of blood until the heart resumes beating. By applying pressure to the sternum, the blood within the heart will be squeezed out of the heart and into the circulation. Proper positioning of the hands on the sternum to perform CPR would be between the lines at T4 and T9.

Visit the American Heart Association website to help locate a course near your home in the United States. There are also many other national and regional heart associations that offer the same service, depending upon the location.

Shape and Size of the Heart

The shape of the heart is similar to a pinecone, rather broad at the superior surface and tapering to the apex. A typical heart is approximately the size of your fist: 12 cm (5 in) in length, 8 cm (3.5 in) wide, and 6 cm (2.5 in) in thickness. Given the size difference between most members of the sexes, the weight of a female heart is approximately 250–300 grams (9 to 11 ounces), and the weight of a male heart is approximately 300–350 grams (11 to 12 ounces). The heart of a well-trained athlete, especially one specializing in aerobic sports, can be considerably larger than this. Cardiac muscle responds to exercise in a manner similar to that of skeletal muscle. That is, exercise results in the addition of protein myofilaments that increase the size of the individual cells without increasing their numbers, a concept called hypertrophy. Hearts of athletes can pump blood more effectively at lower rates than those of nonathletes. Enlarged hearts are not always a result of exercise; they can result from pathologies, such as hypertrophic cardiomyopathy. The cause of an abnormally enlarged heart muscle is unknown, but the condition is often undiagnosed and can cause sudden death in apparently otherwise healthy young people.

Chambers and Circulation through the Heart

The human heart consists of four chambers: The left side and the right side each have one atrium and one ventricle. Each of the upper chambers, the right atrium (plural = atria) and the left atrium, acts as a receiving chamber and contracts to push blood into the lower chambers, the right ventricle and the left ventricle. The ventricles serve as the primary pumping chambers of the heart, propelling blood to the lungs or to the rest of the body.

There are two distinct but linked circuits in the human circulation called the pulmonary and systemic circuits. Although both circuits transport blood and everything it carries, we can initially view the circuits from the point of view of gases. The pulmonary circuit transports blood to and from the lungs, where it picks up oxygen and delivers carbon dioxide for exhalation. The systemic circuit transports oxygenated blood to virtually all of the tissues of the body and returns relatively deoxygenated blood and carbon dioxide to the heart to be sent back to the pulmonary circulation.

The right ventricle pumps deoxygenated blood into the pulmonary trunk, which leads toward the lungs and bifurcates into the left and right pulmonary arteries. These vessels in turn branch many times before reaching the pulmonary capillaries, where gas exchange occurs: Carbon dioxide exits the blood and oxygen enters. The pulmonary trunk arteries and their branches are the only arteries in the post-natal body that carry relatively deoxygenated blood. Highly oxygenated blood returning from the pulmonary capillaries in the lungs passes through a series of vessels that join together to form the pulmonary veins—the only post-natal veins in the body that carry highly oxygenated blood. The pulmonary veins conduct blood into the left atrium, which pumps the blood into the left ventricle, which in turn pumps oxygenated blood into the aorta and on to the many branches of the systemic circuit. Eventually, these vessels will lead to the systemic capillaries, where exchange with the tissue fluid and cells of the body occurs. In this case, oxygen and nutrients exit the systemic capillaries to be used by the cells in their metabolic processes, and carbon dioxide and waste products will enter the blood.

The blood exiting the systemic capillaries is lower in oxygen concentration than when it entered. The capillaries will ultimately unite to form venules, joining to form ever-larger veins, eventually flowing into the two major systemic veins, the superior vena cava and the inferior vena cava, which return blood to the right atrium. The blood in the superior and inferior venae cavae flows into the right atrium, which pumps blood into the right ventricle. This process of blood circulation continues as long as the individual remains alive. Understanding the flow of blood through the pulmonary and systemic circuits is critical to all health professions.

Figure 3. Blood flows from the right atrium to the right ventricle, where it is pumped into the pulmonary circuit. The blood in the pulmonary artery branches is low in oxygen but relatively high in carbon dioxide. Gas exchange occurs in the pulmonary capillaries (oxygen into the blood, carbon dioxide out), and blood high in oxygen and low in carbon dioxide is returned to the left atrium. From here, blood enters the left ventricle, which pumps it into the systemic circuit. Following exchange in the systemic capillaries (oxygen and nutrients out of the capillaries and carbon dioxide and wastes in), blood returns to the right atrium and the cycle is repeated.

Membranes, Surface Features, and Layers

Our exploration of more in-depth heart structures begins by examining the membrane that surrounds the heart, the prominent surface features of the heart, and the layers that form the wall of the heart. Each of these components plays its own unique role in terms of function.

Membranes

Figure 4. The pericardial membrane that surrounds the heart consists of three layers and the pericardial cavity. The heart wall also consists of three layers. The pericardial membrane and the heart wall share the epicardium.

The membrane that directly surrounds the heart and defines the pericardial cavity is called the pericardium or pericardial sac. It also surrounds the “roots” of the major vessels, or the areas of closest proximity to the heart. The pericardium, which literally translates as “around the heart,” consists of two distinct sublayers: the sturdy outer fibrous pericardium and the inner serous pericardium. The fibrous pericardium is made of tough, dense connective tissue that protects the heart and maintains its position in the thorax. The more delicate serous pericardium consists of two layers: the parietal pericardium, which is fused to the fibrous pericardium, and an inner visceral pericardium, or epicardium, which is fused to the heart and is part of the heart wall. The pericardial cavity, filled with lubricating serous fluid, lies between the epicardium and the pericardium.

In most organs within the body, visceral serous membranes such as the epicardium are microscopic. However, in the case of the heart, it is not a microscopic layer but rather a macroscopic layer, consisting of a simple squamous epithelium called a mesothelium, reinforced with loose, irregular, or areolar connective tissue that attaches to the pericardium. This mesothelium secretes the lubricating serous fluid that fills the pericardial cavity and reduces friction as the heart contracts.

Disorders

of the Heart

Cardiac Tamponade

If excess fluid builds within the pericardial space, it can lead to a condition called cardiac tamponade, or pericardial tamponade. With each contraction of the heart, more fluid—in most instances, blood—accumulates within the pericardial cavity. In order to fill with blood for the next contraction, the heart must relax. However, the excess fluid in the pericardial cavity puts pressure on the heart and prevents full relaxation, so the chambers within the heart contain slightly less blood as they begin each heart cycle. Over time, less and less blood is ejected from the heart. If the fluid builds up slowly, as in hypothyroidism, the pericardial cavity may be able to expand gradually to accommodate this extra volume. Some cases of fluid in excess of one liter within the pericardial cavity have been reported. Rapid accumulation of as little as 100 mL of fluid following trauma may trigger cardiac tamponade. Other common causes include myocardial rupture, pericarditis, cancer, or even cardiac surgery. Removal of this excess fluid requires insertion of drainage tubes into the pericardial cavity. Premature removal of these drainage tubes, for example, following cardiac surgery, or clot formation within these tubes are causes of this condition. Untreated, cardiac tamponade can lead to death.

Surface Features of the Heart

Inside the pericardium, the surface features of the heart are visible, including the four chambers. There is a superficial leaf-like extension of the atria near the superior surface of the heart, one on each side, called an auricle—a name that means “ear like”—because its shape resembles the external ear of a human (Figure 5). Auricles are relatively thin-walled structures that can fill with blood and empty into the atria or upper chambers of the heart. You may also hear them referred to as atrial appendages. Also prominent is a series of fat-filled grooves, each of which is known as a sulcus (plural = sulci), along the superior surfaces of the heart. Major coronary blood vessels are located in these sulci. The deep coronary sulcus is located between the atria and ventricles. Located between the left and right ventricles are two additional sulci that are not as deep as the coronary sulcus. The anterior interventricular sulcus is visible on the anterior surface of the heart, whereas the posterior interventricular sulcus is visible on the posterior surface of the heart. Figure 5 illustrates anterior and posterior views of the surface of the heart.

Figure 5. Inside the pericardium, the surface features of the heart are visible.

Layers

The wall of the heart is composed of three layers of unequal thickness. From superficial to deep, these are the epicardium, the myocardium, and the endocardium. The outermost layer of the wall of the heart is also the innermost layer of the pericardium, the epicardium, or the visceral pericardium discussed earlier.

Figure 6. The swirling pattern of cardiac muscle tissue contributes significantly to the heart’s ability to pump blood effectively.

The middle and thickest layer is the myocardium, made largely of cardiac muscle cells. It is built upon a framework of collagenous fibers, plus the blood vessels that supply the myocardium and the nerve fibers that help regulate the heart. It is the contraction of the myocardium that pumps blood through the heart and into the major arteries. The muscle pattern is elegant and complex, as the muscle cells swirl and spiral around the chambers of the heart. They form a figure 8 pattern around the atria and around the bases of the great vessels. Deeper ventricular muscles also form a figure 8 around the two ventricles and proceed toward the apex. More superficial layers of ventricular muscle wrap around both ventricles. This complex swirling pattern allows the heart to pump blood more effectively than a simple linear pattern would. Figure 6 illustrates the arrangement of muscle cells.

Although the ventricles on the right and left sides pump the same amount of blood per contraction, the muscle of the left ventricle is much thicker and better developed than that of the right ventricle. In order to overcome the high resistance required to pump blood into the long systemic circuit, the left ventricle must generate a great amount of pressure. The right ventricle does not need to generate as much pressure, since the pulmonary circuit is shorter and provides less resistance. The image below illustrates the differences in muscular thickness needed for each of the ventricles.

Figure 7. The myocardium in the left ventricle is significantly thicker than that of the right ventricle. Both ventricles pump the same amount of blood, but the left ventricle must generate a much greater pressure to overcome greater resistance in the systemic circuit. The ventricles are shown in both relaxed and contracting states. Note the differences in the relative size of the lumens, the region inside each ventricle where the blood is contained.

The innermost layer of the heart wall, the endocardium, is joined to the myocardium with a thin layer of connective tissue. The endocardium lines the chambers where the blood circulates and covers the heart valves. It is made of simple squamous epithelium called endothelium, which is continuous with the endothelial lining of the blood vessels.

Once regarded as a simple lining layer, recent evidence indicates that the endothelium of the endocardium and the coronary capillaries may play active roles in regulating the contraction of the muscle within the myocardium. The endothelium may also regulate the growth patterns of the cardiac muscle cells throughout life, and the endothelins it secretes create an environment in the surrounding tissue fluids that regulates ionic concentrations and states of contractility. Endothelins are potent vasoconstrictors and, in a normal individual, establish a homeostatic balance with other vasoconstrictors and vasodilators.

Internal Structure of the Heart

Recall that the heart’s contraction cycle follows a dual pattern of circulation—the pulmonary and systemic circuits—because of the pairs of chambers that pump blood into the circulation. In order to develop a more precise understanding of cardiac function, it is first necessary to explore the internal anatomical structures in more detail.

Septa of the Heart

The word septum is derived from the Latin for “something that encloses;” in this case, a septum (plural = septa) refers to a wall or partition that divides the heart into chambers. The septa are physical extensions of the myocardium lined with endocardium. Located between the two atria is the interatrial septum. Normally in an adult heart, the interatrial septum bears an oval-shaped depression known as the fossa ovalis, a remnant of an opening in the fetal heart known as the foramen ovale. The foramen ovale allowed blood in the fetal heart to pass directly from the right atrium to the left atrium, allowing some blood to bypass the pulmonary circuit. Within seconds after birth, a flap of tissue known as the septum primum that previously acted as a valve closes the foramen ovale and establishes the typical cardiac circulation pattern.

Between the two ventricles is a second septum known as the interventricular septum. Unlike the interatrial septum, the interventricular septum is normally intact after its formation during fetal development. It is substantially thicker than the interatrial septum, since the ventricles generate far greater pressure when they contract.

The septum between the atria and ventricles is known as the atrioventricular septum. It is marked by the presence of four openings that allow blood to move from the atria into the ventricles and from the ventricles into the pulmonary trunk and aorta. Located in each of these openings between the atria and ventricles is a valve, a specialized structure that ensures one-way flow of blood. The valves between the atria and ventricles are known generically as atrioventricular valves. The valves at the openings that lead to the pulmonary trunk and aorta are known generically as semilunar valves. The interventricular septum is visible in the image below. In this figure, the atrioventricular septum has been removed to better show the bicupid and tricuspid valves; the interatrial septum is not visible, since its location is covered by the aorta and pulmonary trunk. Since these openings and valves structurally weaken the atrioventricular septum, the remaining tissue is heavily reinforced with dense connective tissue called the cardiac skeleton, or skeleton of the heart. It includes four rings that surround the openings between the atria and ventricles, and the openings to the pulmonary trunk and aorta, and serve as the point of attachment for the heart valves. The cardiac skeleton also provides an important boundary in the heart electrical conduction system.

Figure 8. This anterior view of the heart shows the four chambers, the major vessels and their early branches, as well as the valves. The presence of the pulmonary trunk and aorta covers the interatrial septum, and the atrioventricular septum is cut away to show the atrioventricular valves.

Disorders

of the Heart: Heart Defects

One very common form of interatrial septum pathology is patent foramen ovale, which occurs when the septum primum does not close at birth, and the fossa ovalis is unable to fuse. The word patent is from the Latin root patens for “open.” It may be benign or asymptomatic, perhaps never being diagnosed, or in extreme cases, it may require surgical repair to close the opening permanently. As much as 20–25 percent of the general population may have a patent foramen ovale, but fortunately, most have the benign, asymptomatic version. Patent foramen ovale is normally detected by auscultation of a heart murmur (an abnormal heart sound) and confirmed by imaging with an echocardiogram. Despite its prevalence in the general population, the causes of patent ovale are unknown, and there are no known risk factors. In nonlife-threatening cases, it is better to monitor the condition than to risk heart surgery to repair and seal the opening.

Coarctation of the aorta is a congenital abnormal narrowing of the aorta that is normally located at the insertion of the ligamentum arteriosum, the remnant of the fetal shunt called the ductus arteriosus. If severe, this condition drastically restricts blood flow through the primary systemic artery, which is life threatening. In some individuals, the condition may be fairly benign and not detected until later in life. Detectable symptoms in an infant include difficulty breathing, poor appetite, trouble feeding, or failure to thrive. In older individuals, symptoms include dizziness, fainting, shortness of breath, chest pain, fatigue, headache, and nosebleeds. Treatment involves surgery to resect (remove) the affected region or angioplasty to open the abnormally narrow passageway. Studies have shown that the earlier the surgery is performed, the better the chance of survival.

A patent ductus arteriosus is a congenital condition in which the ductus arteriosus fails to close. The condition may range from severe to benign. Failure of the ductus arteriosus to close results in blood flowing from the higher pressure aorta into the lower pressure pulmonary trunk. This additional fluid moving toward the lungs increases pulmonary pressure and makes respiration difficult. Symptoms include shortness of breath (dyspnea), tachycardia, enlarged heart, a widened pulse pressure, and poor weight gain in infants. Treatments include surgical closure (ligation), manual closure using platinum coils or specialized mesh inserted via the femoral artery or vein, or nonsteroidal anti-inflammatory drugs to block the synthesis of prostaglandin E2, which maintains the vessel in an open position. If untreated, the condition can result in congestive heart failure.

Septal defects are not uncommon in individuals and may be congenital or caused by various disease processes. Tetralogy of Fallot is a congenital condition that may also occur from exposure to unknown environmental factors; it occurs when there is an opening in the interventricular septum caused by blockage of the pulmonary trunk, normally at the pulmonary semilunar valve. This allows blood that is relatively low in oxygen from the right ventricle to flow into the left ventricle and mix with the blood that is relatively high in oxygen. Symptoms include a distinct heart murmur, low blood oxygen percent saturation, dyspnea or difficulty in breathing, polycythemia, broadening (clubbing) of the fingers and toes, and in children, difficulty in feeding or failure to grow and develop. It is the most common cause of cyanosis following birth. The term “tetralogy” is derived from the four components of the condition, although only three may be present in an individual patient: pulmonary infundibular stenosis (rigidity of the pulmonary valve), overriding aorta (the aorta is shifted above both ventricles), ventricular septal defect (opening), and right ventricular hypertrophy (enlargement of the right ventricle). Other heart defects may also accompany this condition, which is typically confirmed by echocardiography imaging. Tetralogy of Fallot occurs in approximately 400 out of one million live births. Normal treatment involves extensive surgical repair, including the use of stents to redirect blood flow and replacement of valves and patches to repair the septal defect, but the condition has a relatively high mortality. Survival rates are currently 75 percent during the first year of life; 60 percent by 4 years of age; 30 percent by 10 years; and 5 percent by 40 years.

In the case of severe septal defects, including both tetralogy of Fallot and patent foramen ovale, failure of the heart to develop properly can lead to a condition commonly known as a “blue baby.” Regardless of normal skin pigmentation, individuals with this condition have an insufficient supply of oxygenated blood, which leads to cyanosis, a blue or purple coloration of the skin, especially when active.

Septal defects are commonly first detected through auscultation, listening to the chest using a stethoscope. In this case, instead of hearing normal heart sounds attributed to the flow of blood and closing of heart valves, unusual heart sounds may be detected. This is often followed by medical imaging to confirm or rule out a diagnosis. In many cases, treatment may not be needed. Some common congenital heart defects are illustrated in Figure 9.

Figure 9. (a) A patent foramen ovale defect is an abnormal opening in the interatrial septum, or more commonly, a failure of the foramen ovale to close. (b) Coarctation of the aorta is an abnormal narrowing of the aorta. (c) A patent ductus arteriosus is the failure of the ductus arteriosus to close. (d) Tetralogy of Fallot includes an abnormal opening in the interventricular septum.

Right Atrium

The right atrium serves as the receiving chamber for blood returning to the heart from the systemic circulation. The two major systemic veins, the superior and inferior venae cavae, and the large coronary vein called the coronary sinus that drains the heart myocardium empty into the right atrium. The superior vena cava drains blood from regions superior to the diaphragm: the head, neck, upper limbs, and the thoracic region. It empties into the superior and posterior portions of the right atrium. The inferior vena cava drains blood from areas inferior to the diaphragm: the lower limbs and abdominopelvic region of the body. It, too, empties into the posterior portion of the atria, but inferior to the opening of the superior vena cava. Immediately superior and slightly medial to the opening of the inferior vena cava on the posterior surface of the atrium is the opening of the coronary sinus. This thin-walled vessel drains most of the coronary veins that return systemic blood from the heart. The majority of the internal heart structures discussed in this and subsequent sections are illustrated in Figure 8.

While the bulk of the internal surface of the right atrium is smooth, the depression of the fossa ovalis is medial, and the anterior surface demonstrates prominent ridges of muscle called the pectinate muscles. The right auricle also has pectinate muscles. The left atrium does not have pectinate muscles except in the auricle.

The atria receive venous blood on a nearly continuous basis, preventing venous flow from stopping while the ventricles are contracting. While most ventricular filling occurs while the atria are relaxed, they do demonstrate a contractile phase and actively pump blood into the ventricles just prior to ventricular contraction. The opening between the atrium and ventricle is guarded by the tricuspid valve.

Right Ventricle

The right ventricle receives blood from the right atrium through the tricuspid valve. Each flap of the valve is attached to strong strands of connective tissue, the chordae tendineae, literally “tendinous cords,” or sometimes more poetically referred to as “heart strings.” There are several chordae tendineae associated with each of the flaps. They are composed of approximately 80 percent collagenous fibers with the remainder consisting of elastic fibers and endothelium. They connect each of the flaps to a papillary muscle that extends from the inferior ventricular surface. There are three papillary muscles in the right ventricle, called the anterior, posterior, and septal muscles, which correspond to the three sections of the valves.

When the myocardium of the ventricle contracts, pressure within the ventricular chamber rises. Blood, like any fluid, flows from higher pressure to lower pressure areas, in this case, toward the pulmonary trunk and the atrium. To prevent any potential backflow, the papillary muscles also contract, generating tension on the chordae tendineae. This prevents the flaps of the valves from being forced into the atria and regurgitation of the blood back into the atria during ventricular contraction.The image below shows papillary muscles and chordae tendineae attached to the tricuspid valve.

Figure 10. In this frontal section, you can see papillary muscles attached to the tricuspid valve on the right as well as the mitral valve on the left via chordae tendineae. (credit: modification of work by “PV KS”/flickr.com)

The walls of the ventricle are lined with trabeculae carneae, ridges of cardiac muscle covered by endocardium. In addition to these muscular ridges, a band of cardiac muscle, also covered by endocardium, known as the moderator band reinforces the thin walls of the right ventricle and plays a crucial role in cardiac conduction. It arises from the inferior portion of the interventricular septum and crosses the interior space of the right ventricle to connect with the inferior papillary muscle.

When the right ventricle contracts, it ejects blood into the pulmonary trunk, which branches into the left and right pulmonary arteries that carry it to each lung. The superior surface of the right ventricle begins to taper as it approaches the pulmonary trunk. At the base of the pulmonary trunk is the pulmonary semilunar valve that prevents backflow from the pulmonary trunk.

Left Atrium

After exchange of gases in the pulmonary capillaries, blood returns to the left atrium high in oxygen via one of the four pulmonary veins. While the left atrium does not contain pectinate muscles, it does have an auricle that includes these pectinate ridges. Blood flows nearly continuously from the pulmonary veins back into the atrium, which acts as the receiving chamber, and from here through an opening into the left ventricle. Most blood flows passively into the heart while both the atria and ventricles are relaxed, but toward the end of the ventricular relaxation period, the left atrium will contract, pumping blood into the ventricle. This atrial contraction accounts for approximately 20 percent of ventricular filling. The opening between the left atrium and ventricle is guarded by the mitral valve.

Left Ventricle

Recall that, although both sides of the heart will pump the same amount of blood, the muscular layer is much thicker in the left ventricle compared to the right. Like the right ventricle, the left also has trabeculae carneae, but there is no moderator band. The mitral valve is connected to papillary muscles via chordae tendineae. There are two papillary muscles on the left—the anterior and posterior—as opposed to three on the right.

The left ventricle is the major pumping chamber for the systemic circuit; it ejects blood into the aorta through the aortic semilunar valve.

Heart Valve Structure and Function

Figure 11. With the atria and major vessels removed, all four valves are clearly visible, although it is difficult to distinguish the three separate cusps of the tricuspid valve.

A transverse section through the heart slightly above the level of the atrioventricular septum reveals all four heart valves along the same plane (Figure 11). The valves ensure unidirectional blood flow through the heart. Between the right atrium and the right ventricle is the right atrioventricular valve, or tricuspid valve. It typically consists of three flaps, or leaflets, made of endocardium reinforced with additional connective tissue. The flaps are connected by chordae tendineae to the papillary muscles, which control the opening and closing of the valves.

Emerging from the right ventricle at the base of the pulmonary trunk is the pulmonary semilunar valve, or the pulmonary valve; it is also known as the pulmonic valve or the right semilunar valve. The pulmonary valve is comprised of three small flaps of endothelium reinforced with connective tissue. When the ventricle relaxes, the pressure differential causes blood to flow back into the ventricle from the pulmonary trunk. This flow of blood fills the pocket-like flaps of the pulmonary valve, causing the valve to close and producing an audible sound. Unlike the atrioventricular valves, there are no papillary muscles or chordae tendineae associated with the pulmonary valve.

Located at the opening between the left atrium and left ventricle is the mitral valve, also called the bicuspid valve or the left atrioventricular valve. Structurally, this valve consists of two cusps, known as the anterior medial cusp and the posterior medial cusp, compared to the three cusps of the tricuspid valve. In a clinical setting, the valve is referred to as the mitral valve, rather than the bicuspid valve. The two cusps of the mitral valve are attached by chordae tendineae to two papillary muscles that project from the wall of the ventricle.

At the base of the aorta is the aortic semilunar valve, or the aortic valve, which prevents backflow from the aorta. It normally is composed of three flaps. When the ventricle relaxes and blood attempts to flow back into the ventricle from the aorta, blood will fill the cusps of the valve, causing it to close and producing an audible sound.

In the image above, the two atrioventricular valves are open and the two semilunar valves are closed. This occurs when both atria and ventricles are relaxed and when the atria contract to pump blood into the ventricles. The image below shows a frontal view. Although only the left side of the heart is illustrated, the process is virtually identical on the right.

Figure 12. (a) A transverse section through the heart illustrates the four heart valves. The two atrioventricular valves are open; the two semilunar valves are closed. The atria and vessels have been removed. (b) A frontal section through the heart illustrates blood flow through the mitral valve. When the mitral valve is open, it allows blood to move from the left atrium to the left ventricle. The aortic semilunar valve is closed to prevent backflow of blood from the aorta to the left ventricle.

Image a above shows the atrioventricular valves closed while the two semilunar valves are open. This occurs when the ventricles contract to eject blood into the pulmonary trunk and aorta. Closure of the two atrioventricular valves prevents blood from being forced back into the atria. This stage can be seen from a frontal view in image b above.

Figure 13. (a) A transverse section through the heart illustrates the four heart valves during ventricular contraction. The two atrioventricular valves are closed, but the two semilunar valves are open. The atria and vessels have been removed. (b) A frontal view shows the closed mitral (bicuspid) valve that prevents backflow of blood into the left atrium. The aortic semilunar valve is open to allow blood to be ejected into the aorta.

When the ventricles begin to contract, pressure within the ventricles rises and blood flows toward the area of lowest pressure, which is initially in the atria. This backflow causes the cusps of the tricuspid and mitral (bicuspid) valves to close. These valves are tied down to the papillary muscles by chordae tendineae. During the relaxation phase of the cardiac cycle, the papillary muscles are also relaxed and the tension on the chordae tendineae is slight (image b above). However, as the myocardium of the ventricle contracts, so do the papillary muscles. This creates tension on the chordae tendineae (image b above), helping to hold the cusps of the atrioventricular valves in place and preventing them from being blown back into the atria.

The aortic and pulmonary semilunar valves lack the chordae tendineae and papillary muscles associated with the atrioventricular valves. Instead, they consist of pocket-like folds of endocardium reinforced with additional connective tissue. When the ventricles relax and the change in pressure forces the blood toward the ventricles, the blood presses against these cusps and seals the openings.

Practice Question

Figure 14 shows an echocardiogram of actual heart valves opening and closing. Although much of the heart has been “removed” from this gif loop so the chordae tendineae are not visible, why is their presence more critical for the atrioventricular valves (tricuspid and mitral) than the semilunar (aortic and pulmonary) valves?

Figure 14. An echocardiogram of heart valves

Show Answer

The pressure gradient between the atria and the ventricles is much greater than that between the ventricles and the pulmonary trunk and aorta. Without the presence of the chordae tendineae and papillary muscles, the valves would be blown back (prolapsed) into the atria and blood would regurgitate.

Disorders

of the Heart Valves

When heart valves do not function properly, they are often described as incompetent and result in valvular heart disease, which can range from benign to lethal. Some of these conditions are congenital, that is, the individual was born with the defect, whereas others may be attributed to disease processes or trauma. Some malfunctions are treated with medications, others require surgery, and still others may be mild enough that the condition is merely monitored since treatment might trigger more serious consequences.

Valvular disorders are often caused by carditis, or inflammation of the heart. One common trigger for this inflammation is rheumatic fever, or scarlet fever, an autoimmune response to the presence of a bacterium, Streptococcus pyogenes, normally a disease of childhood.

While any of the heart valves may be involved in valve disorders, mitral regurgitation is the most common, detected in approximately 2 percent of the population, and the pulmonary semilunar valve is the least frequently involved. When a valve malfunctions, the flow of blood to a region will often be disrupted. The resulting inadequate flow of blood to this region will be described in general terms as an insufficiency. The specific type of insufficiency is named for the valve involved: aortic insufficiency, mitral insufficiency, tricuspid insufficiency, or pulmonary insufficiency.

If one of the cusps of the valve is forced backward by the force of the blood, the condition is referred to as a prolapsed valve. Prolapse may occur if the chordae tendineae are damaged or broken, causing the closure mechanism to fail. The failure of the valve to close properly disrupts the normal one-way flow of blood and results in regurgitation, when the blood flows backward from its normal path. Using a stethoscope, the disruption to the normal flow of blood produces a heart murmur.

Stenosis is a condition in which the heart valves become rigid and may calcify over time. The loss of flexibility of the valve interferes with normal function and may cause the heart to work harder to propel blood through the valve, which eventually weakens the heart. Aortic stenosis affects approximately 2 percent of the population over 65 years of age, and the percentage increases to approximately 4 percent in individuals over 85 years. Occasionally, one or more of the chordae tendineae will tear or the papillary muscle itself may die as a component of a myocardial infarction (heart attack). In this case, the patient’s condition will deteriorate dramatically and rapidly, and immediate surgical intervention may be required.

Auscultation, or listening to a patient’s heart sounds, is one of the most useful diagnostic tools, since it is proven, safe, and inexpensive. The term auscultation is derived from the Latin for “to listen,” and the technique has been used for diagnostic purposes as far back as the ancient Egyptians. Valve and septal disorders will trigger abnormal heart sounds. If a valvular disorder is detected or suspected, a test called an echocardiogram, or simply an “echo,” may be ordered. Echocardiograms are sonograms of the heart and can help in the diagnosis of valve disorders as well as a wide variety of heart pathologies.

Visit this site for a free download, including excellent animations and audio of heart sounds.

Career Connection: Cardiologist

Cardiologists are medical doctors that specialize in the diagnosis and treatment of diseases of the heart. After completing 4 years of medical school, cardiologists complete a three-year residency in internal medicine followed by an additional three or more years in cardiology. Following this 10-year period of medical training and clinical experience, they qualify for a rigorous two-day examination administered by the Board of Internal Medicine that tests their academic training and clinical abilities, including diagnostics and treatment. After successful completion of this examination, a physician becomes a board-certified cardiologist. Some board-certified cardiologists may be invited to become a Fellow of the American College of Cardiology (FACC). This professional recognition is awarded to outstanding physicians based upon merit, including outstanding credentials, achievements, and community contributions to cardiovascular medicine.

Visit this site to learn more about cardiologists.

Career Connection: Cardiovascular Technologist/Technician

Cardiovascular technologists/technicians are trained professionals who perform a variety of imaging techniques, such as sonograms or echocardiograms, used by physicians to diagnose and treat diseases of the heart. Nearly all of these positions require an associate degree, and these technicians earn a median salary of $49,410 as of May 2010, according to the U.S. Bureau of Labor Statistics. Growth within the field is fast, projected at 29 percent from 2010 to 2020.

There is a considerable overlap and complementary skills between cardiac technicians and vascular technicians, and so the term cardiovascular technician is often used. Special certifications within the field require documenting appropriate experience and completing additional and often expensive certification examinations. These subspecialties include Certified Rhythm Analysis Technician (CRAT), Certified Cardiographic Technician (CCT), Registered Congenital Cardiac Sonographer (RCCS), Registered Cardiac Electrophysiology Specialist (RCES), Registered Cardiovascular Invasive Specialist (RCIS), Registered Cardiac Sonographer (RCS), Registered Vascular Specialist (RVS), and Registered Phlebology Sonographer (RPhS).

Visit this site for more information on cardiovascular technologists/technicians.

Coronary Circulation

You will recall that the heart is a remarkable pump composed largely of cardiac muscle cells that are incredibly active throughout life. Like all other cells, a cardiomyocyte requires a reliable supply of oxygen and nutrients, and a way to remove wastes, so it needs a dedicated, complex, and extensive coronary circulation. And because of the critical and nearly ceaseless activity of the heart throughout life, this need for a blood supply is even greater than for a typical cell. However, coronary circulation is not continuous; rather, it cycles, reaching a peak when the heart muscle is relaxed and nearly ceasing while it is contracting.

Coronary Arteries

Coronary arteries supply blood to the myocardium and other components of the heart. The first portion of the aorta after it arises from the left ventricle gives rise to the coronary arteries. There are three dilations in the wall of the aorta just superior to the aortic semilunar valve. Two of these, the left posterior aortic sinus and anterior aortic sinus, give rise to the left and right coronary arteries, respectively. The third sinus, the right posterior aortic sinus, typically does not give rise to a vessel. Coronary vessel branches that remain on the surface of the artery and follow the sulci are called epicardial coronary arteries.

The left coronary artery distributes blood to the left side of the heart, the left atrium and ventricle, and the interventricular septum. The circumflex artery arises from the left coronary artery and follows the coronary sulcus to the left. Eventually, it will fuse with the small branches of the right coronary artery. The larger anterior interventricular artery, also known as the left anterior descending artery (LAD), is the second major branch arising from the left coronary artery. It follows the anterior interventricular sulcus around the pulmonary trunk. Along the way it gives rise to numerous smaller branches that interconnect with the branches of the posterior interventricular artery, forming anastomoses. An anastomosis is an area where vessels unite to form interconnections that normally allow blood to circulate to a region even if there may be partial blockage in another branch. The anastomoses in the heart are very small. Therefore, this ability is somewhat restricted in the heart so a coronary artery blockage often results in death of the cells (myocardial infarction) supplied by the particular vessel.

The right coronary artery proceeds along the coronary sulcus and distributes blood to the right atrium, portions of both ventricles, and the heart conduction system. Normally, one or more marginal arteries arise from the right coronary artery inferior to the right atrium. The marginal arteries supply blood to the superficial portions of the right ventricle. On the posterior surface of the heart, the right coronary artery gives rise to the posterior interventricular artery, also known as the posterior descending artery. It runs along the posterior portion of the interventricular sulcus toward the apex of the heart, giving rise to branches that supply the interventricular septum and portions of both ventricles. Figure 15 presents views of the coronary circulation from both the anterior and posterior views.

Figure 15. The anterior view of the heart shows the prominent coronary surface vessels. The posterior view of the heart shows the prominent coronary surface vessels.

Diseases of the Heart: Myocardial Infarction

Myocardial infarction (MI) is the formal term for what is commonly referred to as a heart attack. It normally results from a lack of blood flow (ischemia) and oxygen (hypoxia) to a region of the heart, resulting in death of the cardiac muscle cells. An MI often occurs when a coronary artery is blocked by the buildup of atherosclerotic plaque consisting of lipids, cholesterol and fatty acids, and white blood cells, primarily macrophages. It can also occur when a portion of an unstable atherosclerotic plaque travels through the coronary arterial system and lodges in one of the smaller vessels. The resulting blockage restricts the flow of blood and oxygen to the myocardium and causes death of the tissue. MIs may be triggered by excessive exercise, in which the partially occluded artery is no longer able to pump sufficient quantities of blood, or severe stress, which may induce spasm of the smooth muscle in the walls of the vessel.

In the case of acute MI, there is often sudden pain beneath the sternum (retrosternal pain) called angina pectoris, often radiating down the left arm in males but not in female patients. Until this anomaly between the sexes was discovered, many female patients suffering MIs were misdiagnosed and sent home. In addition, patients typically present with difficulty breathing and shortness of breath (dyspnea), irregular heartbeat (palpations), nausea and vomiting, sweating (diaphoresis), anxiety, and fainting (syncope), although not all of these symptoms may be present. Many of the symptoms are shared with other medical conditions, including anxiety attacks and simple indigestion, so differential diagnosis is critical. It is estimated that between 22 and 64 percent of MIs present without any symptoms.

An MI can be confirmed by examining the patient’s ECG, which frequently reveals alterations in the ST and Q components. Some classification schemes of MI are referred to as ST-elevated MI (STEMI) and non-elevated MI (non-STEMI). In addition, echocardiography or cardiac magnetic resonance imaging may be employed. Common blood tests indicating an MI include elevated levels of creatine kinase MB (an enzyme that catalyzes the conversion of creatine to phosphocreatine, consuming ATP) and cardiac troponin (the regulatory protein for muscle contraction), both of which are released by damaged cardiac muscle cells.

Immediate treatments for MI are essential and include administering supplemental oxygen, aspirin that helps to break up clots, and nitroglycerine administered sublingually (under the tongue) to facilitate its absorption. Despite its unquestioned success in treatments and use since the 1880s, the mechanism of nitroglycerine is still incompletely understood but is believed to involve the release of nitric oxide, a known vasodilator, and endothelium-derived releasing factor, which also relaxes the smooth muscle in the tunica media of coronary vessels. Longer-term treatments include injections of thrombolytic agents such as streptokinase that dissolve the clot, the anticoagulant heparin, balloon angioplasty and stents to open blocked vessels, and bypass surgery to allow blood to pass around the site of blockage. If the damage is extensive, coronary replacement with a donor heart or coronary assist device, a sophisticated mechanical device that supplements the pumping activity of the heart, may be employed. Despite the attention, development of artificial hearts to augment the severely limited supply of heart donors has proven less than satisfactory but will likely improve in the future.

MIs may trigger cardiac arrest, but the two are not synonymous. Important risk factors for MI include cardiovascular disease, age, smoking, high blood levels of the low-density lipoprotein (LDL, often referred to as “bad” cholesterol), low levels of high-density lipoprotein (HDL, or “good” cholesterol), hypertension, diabetes mellitus, obesity, lack of physical exercise, chronic kidney disease, excessive alcohol consumption, and use of illegal drugs.

Coronary Veins

Coronary veins drain the heart and generally parallel the large surface arteries. The great cardiac vein can be seen initially on the surface of the heart following the interventricular sulcus, but it eventually flows along the coronary sulcus into the coronary sinus on the posterior surface. The great cardiac vein initially parallels the anterior interventricular artery and drains the areas supplied by this vessel. It receives several major branches, including the posterior cardiac vein, the middle cardiac vein, and the small cardiac vein. The posterior cardiac vein parallels and drains the areas supplied by the marginal artery branch of the circumflex artery. The middle cardiac vein parallels and drains the areas supplied by the posterior interventricular artery. The small cardiac vein parallels the right coronary artery and drains the blood from the posterior surfaces of the right atrium and ventricle. The coronary sinus is a large, thin-walled vein on the posterior surface of the heart lying within the atrioventricular sulcus and emptying directly into the right atrium. The anterior cardiac veins parallel the small cardiac arteries and drain the anterior surface of the right ventricle. Unlike these other cardiac veins, it bypasses the coronary sinus and drains directly into the right atrium.

Examples

Diseases of the Heart: Coronary Artery Disease

Coronary artery disease is the leading cause of death worldwide. It occurs when the buildup of plaque—a fatty material including cholesterol, connective tissue, white blood cells, and some smooth muscle cells—within the walls of the arteries obstructs the flow of blood and decreases the flexibility or compliance of the vessels. This condition is called atherosclerosis, a hardening of the arteries that involves the accumulation of plaque. As the coronary blood vessels become occluded, the flow of blood to the tissues will be restricted, a condition called ischemia that causes the cells to receive insufficient amounts of oxygen, called hypoxia. The image below shows the blockage of coronary arteries highlighted by the injection of dye. Some individuals with coronary artery disease report pain radiating from the chest called angina pectoris, but others remain asymptomatic. If untreated, coronary artery disease can lead to MI or a heart attack.

Figure 16. In this coronary angiogram (X-ray), the dye makes visible two occluded coronary arteries. Such blockages can lead to decreased blood flow (ischemia) and insufficient oxygen (hypoxia) delivered to the cardiac tissues. If uncorrected, this can lead to cardiac muscle death (myocardial infarction).

The disease progresses slowly and often begins in children and can be seen as fatty “streaks” in the vessels. It then gradually progresses throughout life. Well-documented risk factors include smoking, family history, hypertension, obesity, diabetes, high alcohol consumption, lack of exercise, stress, and hyperlipidemia or high circulating levels of lipids in the blood. Treatments may include medication, changes to diet and exercise, angioplasty with a balloon catheter, insertion of a stent, or coronary bypass procedure.

Angioplasty is a procedure in which the occlusion is mechanically widened with a balloon. A specialized catheter with an expandable tip is inserted into a superficial vessel, normally in the leg, and then directed to the site of the occlusion. At this point, the balloon is inflated to compress the plaque material and to open the vessel to increase blood flow. Then, the balloon is deflated and retracted. A stent consisting of a specialized mesh is typically inserted at the site of occlusion to reinforce the weakened and damaged walls. Stent insertions have been routine in cardiology for more than 40 years.

Coronary bypass surgery may also be performed. This surgical procedure grafts a replacement vessel obtained from another, less vital portion of the body to bypass the occluded area. This procedure is clearly effective in treating patients experiencing a MI, but overall does not increase longevity. Nor does it seem advisable in patients with stable although diminished cardiac capacity since frequently loss of mental acuity occurs following the procedure. Long-term changes to behavior, emphasizing diet and exercise plus a medicine regime tailored to lower blood pressure, lower cholesterol and lipids, and reduce clotting are equally as effective.

Chapter Review

The heart resides within the pericardial sac and is located in the mediastinal space within the thoracic cavity. The pericardial sac consists of two fused layers: an outer fibrous capsule and an inner parietal pericardium lined with a serous membrane. Between the pericardial sac and the heart is the pericardial cavity, which is filled with lubricating serous fluid. The walls of the heart are composed of an outer epicardium, a thick myocardium, and an inner lining layer of endocardium. The human heart consists of a pair of atria, which receive blood and pump it into a pair of ventricles, which pump blood into the vessels. The right atrium receives systemic blood relatively low in oxygen and pumps it into the right ventricle, which pumps it into the pulmonary circuit. Exchange of oxygen and carbon dioxide occurs in the lungs, and blood high in oxygen returns to the left atrium, which pumps blood into the left ventricle, which in turn pumps blood into the aorta and the remainder of the systemic circuit. The septa are the partitions that separate the chambers of the heart. They include the interatrial septum, the interventricular septum, and the atrioventricular septum. Two of these openings are guarded by the atrioventricular valves, the right tricuspid valve and the left mitral valve, which prevent the backflow of blood. Each is attached to chordae tendineae that extend to the papillary muscles, which are extensions of the myocardium, to prevent the valves from being blown back into the atria. The pulmonary valve is located at the base of the pulmonary trunk, and the left semilunar valve is located at the base of the aorta. The right and left coronary arteries are the first to branch off the aorta and arise from two of the three sinuses located near the base of the aorta and are generally located in the sulci. Cardiac veins parallel the small cardiac arteries and generally drain into the coronary sinus.

Self Check

Answer the question(s) below to see how well you understand the topics covered in the previous section.

Critical Thinking Questions

1. Describe how the valves keep the blood moving in one direction.
2. Why is the pressure in the pulmonary circulation lower than in the systemic circulation?

Show Answers

1. When the ventricles contract and pressure begins to rise in the ventricles, there is an initial tendency for blood to flow back (regurgitate) to the atria. However, the papillary muscles also contract, placing tension on the chordae tendineae and holding the atrioventricular valves (tricuspid and mitral) in place to prevent the valves from prolapsing and being forced back into the atria. The semilunar valves (pulmonary and aortic) lack chordae tendineae and papillary muscles, but do not face the same pressure gradients as do the atrioventricular valves. As the ventricles relax and pressure drops within the ventricles, there is a tendency for the blood to flow backward. However, the valves, consisting of reinforced endothelium and connective tissue, fill with blood and seal off the opening preventing the return of blood.
2. The pulmonary circuit consists of blood flowing to and from the lungs, whereas the systemic circuit carries blood to and from the entire body. The systemic circuit is far more extensive, consisting of far more vessels and offers much greater resistance to the flow of blood, so the heart must generate a higher pressure to overcome this resistance. This can be seen in the thickness of the myocardium in the ventricles.

Glossary

anastomosis: (plural = anastomoses) area where vessels unite to allow blood to circulate even if there may be partial blockage in another branch

anterior cardiac veins: vessels that parallel the small cardiac arteries and drain the anterior surface of the right ventricle; bypass the coronary sinus and drain directly into the right atrium

anterior interventricular artery: (also, left anterior descending artery or LAD) major branch of the left coronary artery that follows the anterior interventricular sulcus

anterior interventricular sulcus: sulcus located between the left and right ventricles on the anterior surface of the heart

aortic valve: (also, aortic semilunar valve) valve located at the base of the aorta

atrioventricular septum: cardiac septum located between the atria and ventricles; atrioventricular valves are located here

atrioventricular valves: one-way valves located between the atria and ventricles; the valve on the right is called the tricuspid valve, and the one on the left is the mitral or bicuspid valve

atrium: (plural = atria) upper or receiving chamber of the heart that pumps blood into the lower chambers just prior to their contraction; the right atrium receives blood from the systemic circuit that flows into the right ventricle; the left atrium receives blood from the pulmonary circuit that flows into the left ventricle

auricle: extension of an atrium visible on the superior surface of the heart

bicuspid valve: (also, mitral valve or left atrioventricular valve) valve located between the left atrium and ventricle; consists of two flaps of tissue

cardiac notch: depression in the medial surface of the inferior lobe of the left lung where the apex of the heart is located

cardiac skeleton: (also, skeleton of the heart) reinforced connective tissue located within the atrioventricular septum; includes four rings that surround the openings between the atria and ventricles, and the openings to the pulmonary trunk and aorta; the point of attachment for the heart valves

cardiomyocyte: muscle cell of the heart

chordae tendineae: string-like extensions of tough connective tissue that extend from the flaps of the atrioventricular valves to the papillary muscles

circumflex artery: branch of the left coronary artery that follows coronary sulcus 

coronary arteries: branches of the ascending aorta that supply blood to the heart; the left coronary artery feeds the left side of the heart, the left atrium and ventricle, and the interventricular septum; the right coronary artery feeds the right atrium, portions of both ventricles, and the heart conduction system

coronary sinus: large, thin-walled vein on the posterior surface of the heart that lies within the atrioventricular sulcus and drains the heart myocardium directly into the right atrium

coronary sulcus: sulcus that marks the boundary between the atria and ventricles

coronary veins: vessels that drain the heart and generally parallel the large surface arteries

endocardium: innermost layer of the heart lining the heart chambers and heart valves; composed of endothelium reinforced with a thin layer of connective tissue that binds to the myocardium

endothelium: layer of smooth, simple squamous epithelium that lines the endocardium and blood vessels

epicardial coronary arteries: surface arteries of the heart that generally follow the sulci

epicardium: innermost layer of the serous pericardium and the outermost layer of the heart wall

foramen ovale: opening in the fetal heart that allows blood to flow directly from the right atrium to the left atrium, bypassing the fetal pulmonary circuit

fossa ovalis: oval-shaped depression in the interatrial septum that marks the former location of the foramen ovale

great cardiac vein: vessel that follows the interventricular sulcus on the anterior surface of the heart and flows along the coronary sulcus into the coronary sinus on the posterior surface; parallels the anterior interventricular artery and drains the areas supplied by this vessel

hypertrophic cardiomyopathy: pathological enlargement of the heart, generally for no known reason

inferior vena cava: large systemic vein that returns blood to the heart from the inferior portion of the body

interatrial septum: cardiac septum located between the two atria; contains the fossa ovalis after birth

interventricular septum: cardiac septum located between the two ventricles

left atrioventricular valve: (also, mitral valve or bicuspid valve) valve located between the left atrium and ventricle; consists of two flaps of tissue

marginal arteries: branches of the right coronary artery that supply blood to the superficial portions of the right ventricle

mesothelium: simple squamous epithelial portion of serous membranes, such as the superficial portion of the epicardium (the visceral pericardium) and the deepest portion of the pericardium (the parietal pericardium)

middle cardiac vein: vessel that parallels and drains the areas supplied by the posterior interventricular artery; drains into the great cardiac vein

mitral valve: (also, left atrioventricular valve or bicuspid valve) valve located between the left atrium and ventricle; consists of two flaps of tissue

moderator band: band of myocardium covered by endocardium that arises from the inferior portion of the interventricular septum in the right ventricle and crosses to the anterior papillary muscle; contains conductile fibers that carry electrical signals followed by contraction of the heart

myocardium: thickest layer of the heart composed of cardiac muscle cells built upon a framework of primarily collagenous fibers and blood vessels that supply it and the nervous fibers that help to regulate it

papillary muscle: extension of the myocardium in the ventricles to which the chordae tendineae attach

pectinate muscles: muscular ridges seen on the anterior surface of the right atrium

pericardial cavity: cavity surrounding the heart filled with a lubricating serous fluid that reduces friction
as the heart contracts

pericardial sac: (also, pericardium) membrane that separates the heart from other mediastinal structures; consists of two distinct, fused sublayers: the fibrous pericardium and the parietal pericardium

pericardium: (also, pericardial sac) membrane that separates the heart from other mediastinal structures; consists of two distinct, fused sublayers: the fibrous pericardium and the parietal pericardium

posterior cardiac vein: vessel that parallels and drains the areas supplied by the marginal artery branch of the circumflex artery; drains into the great cardiac vein

posterior interventricular artery: (also, posterior descending artery) branch of the right coronary artery that runs along the posterior portion of the interventricular sulcus toward the apex of the heart and gives rise to branches that supply the interventricular septum and portions of both ventricles

posterior interventricular sulcus: sulcus located between the left and right ventricles on the anterior surface of the heart

pulmonary arteries: left and right branches of the pulmonary trunk that carry deoxygenated blood from the heart to each of the lungs

pulmonary capillaries capillaries surrounding the alveoli of the lungs where gas exchange occurs: carbon dioxide exits the blood and oxygen enters

pulmonary circuit: blood flow to and from the lungs

pulmonary trunk: large arterial vessel that carries blood ejected from the right ventricle; divides into the left and right pulmonary arteries

pulmonary valve: (also, pulmonary semilunar valve, the pulmonic valve, or the right semilunar valve) valve at the base of the pulmonary trunk that prevents backflow of blood into the right ventricle; consists of three flaps

pulmonary veins: veins that carry highly oxygenated blood into the left atrium, which pumps the blood into the left ventricle, which in turn pumps oxygenated blood into the aorta and to the many branches of the systemic circuit

right atrioventricular valve: (also, tricuspid valve) valve located between the right atrium and ventricle; consists of three flaps of tissue

semilunar valves: valves located at the base of the pulmonary trunk and at the base of the aorta

septum: (plural = septa) walls or partitions that divide the heart into chambers

septum primum: flap of tissue in the fetus that covers the foramen ovale within a few seconds after birth

small cardiac vein: parallels the right coronary artery and drains blood from the posterior surfaces of the right atrium and ventricle; drains into the great cardiac vein

sulcus: (plural = sulci) fat-filled groove visible on the surface of the heart; coronary vessels are also located in these areas

superior vena cava: large systemic vein that returns blood to the heart from the superior portion of the body

systemic circuit: blood flow to and from virtually all of the tissues of the body

trabeculae carneae: ridges of muscle covered by endocardium located in the ventricles

tricuspid valve: term used most often in clinical settings for the right atrioventricular valve

valve: in the cardiovascular system, a specialized structure located within the heart or vessels that ensures one-way flow of blood

ventricle: one of the primary pumping chambers of the heart located in the lower portion of the heart; the left ventricle is the major pumping chamber on the lower left side of the heart that ejects blood into the systemic circuit via the aorta and receives blood from the left atrium; the right ventricle is the major pumping chamber on the lower right side of the heart that ejects blood into the pulmonary circuit via the pulmonary trunk and receives blood from the right atrium

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Your heart might skip a beat

ANATOMICAL ACCURACY

Meticulous detail makes this the best 3D heart model ever created. Strip back the layers of the heart and hide or fade individual structures to examine every part.

BEATING HEART

View the heart in action like never before. Set the heart rate to simulate real scenarios, or control the animation to examine every minute movement.

SYSTEMS

Explore body systems related to the heart for a greater overview of how the body functions.

SKELETAL

LUNGS

ARTERIAL

VENOUS

NERVOUS

Trace an artery back to its origin at the heart. Isolate or highlight the path, and explore other structures within the path.

DETAILED VIEW

Go deeper into the anatomy with the blood vessels model. Explore the fine layers and features of the vessels like never before.

AR

Place the heart on a surface in real life to gain a better sense of scale. Continue to interact with the model as you study.

CLINICAL

A wholehearted approach

ANIMATIONS

Visualize pathologies and procedures with comprehensive video animations. Understand how conditions develop and are treated.

SCREENS

Follow-up with clinical Screens, featuring custom model set-ups for analysing conditions, along with complementary text and imagery content.

LIBRARY

Your study won’t be in vein

COURSES

Break down complex cardiac topics with Courses, guided lessons created by leading anatomical experts.

Introduction to Anatomy of the Heart

This course is designed to give you a comprehensive introduction to the anatomy of the heart. It is an interactive, lecture based course covering the underlying concepts and principles related to human gross anatomy of the heart and related structures.

ANATOMY

Get resources on the anatomical structure of the heart quickly and easily with Screens and Recordings. Simply choose the topic you need to revise.

PHYSIOLOGY

Physiology resources give a greater understanding of how the heart functions in relation to the rest of the body, with extra detail included in accompanying text and images.

Muscle contraction mechanism

CREATE

Change of heart

ANNOTATE

Add your own notes or custom diagrams to the model. Draw directly on the model, or add Labels to mark out structures for future reference.

Draw directly on the 3D model using Pen in Complete Heart

EDIT

Change the heart model to show what you need using Tools. Add Growths or Pain to illustrate conditions, or use Cut to access deeper areas of the organ.

Half-hearted

Cut throught the heart to discover new views and gain deeper understanding.

Heartbreaker

Separate the structures of the heart to explore their connections and relationships.

SAVE

Use your custom model set-up to create a Screen, or make a Recording to show and explain the key points of your set-up.

SHARE AND COLLABORATE

A heart-to-heart with your classmates

Brian Smith

joined your group First Semester Groupwork

Michelle Johnson

uploaded new content to First Semester Groupwork

Prof Laura Brown

added a Course to AN1002 Introduction to Gross Anatomy

GROUPS

Use your custom model set-up to create a Screen, or make a Recording to show and explain the key points of your set-up.

SHARE

Choose Groups to share your resources with. Future edits are automatically pushed to the Group, so everybody is always on the same page.

THREE-DAY TRIAL

Follow your heart

Get started with a free 3-day trial of Complete Heart on your chosen platform. Access the entire range of features, and begin experiencing the cardiovascular anatomy like never before.

Complete Heart for iPad

Complete Heart for Mac

DEVICE COMPATIBILITY

iPad

Available on:

iPad Air

iPad Air 2

iPad mini 4

iPad Pro (12.9″ and 9.7″)

iPad (2017)

OS:

iOS 11

Supported accessories:

Apple Pencil

Keyboard

AR Mode compatibility:

iPad Pro (all models)

iPad (2017)

Mac

Available on:

MacBook (late 2008 aluminium or newer)

MacBook Pro (Mid 2007 or newer)

MacBook Air (Late 2008 or newer)

Mac mini (early 2009 or newer)

iMac (2007 or newer)

Mac Pro (early 2008 or newer)

OS:

macOS 10.12 or later

Hardware:

64-bit processor

Windows

OS:

Windows 10 (version 1607, build 14393 or later)

Minimum hardware:

Architecture: x86

DirectX: DirectX 12 API, Hardware Feature Level 11

Memory: 4GB

Processor: Intel Core i5

Keyboard

Mouse

Recommended hardware:

Architecture: x86

DirectX: DirectX 12 API, Hardware Feature Level 11

Memory: 16GB

Touch: Integrated Touch

Camera: Integrated Camera

Processor: Intel Core i7

Graphics: Intel(R) HD Graphics 520, AMD Radeon HD 6700M Series, NVIDIA Geforce GTX 675MX

Keyboard

Mouse

Microphone

Supported accessories:

Microsoft Surface Dial

Microsoft Surface Pen





Anatomy, how it works, and more

The human heart is a finely-tuned instrument that serves the whole body. It is a muscular organ around the size of a closed fist, and it sits in the chest, slightly to the left of center.

The heart beats around 100,000 times a day, pumping approximately 8 pints of blood throughout the body 24/7. This delivers oxygen- and nutrient-rich blood to tissues and organs and carries away waste.

The heart sends deoxygenated blood to the lungs, where the blood loads up with oxygen and unloads carbon dioxide, a waste product of metabolism.

Together, the heart, blood, and blood vessels — arteries, capillaries, and veins — make up the circulatory system.

In this article, we explore the structure of the heart, how it pumps blood around the body, and the electrical system that controls it.

Below is an interactive 3D model of the heart. Explore the model using your mouse pad or touchscreen to learn more.

The heart consists of four chambers:

• The atria: These are the two upper chambers, which receive blood.
• The ventricles: These are the two lower chambers, which discharge blood.

A wall of tissue called the septum separates the left and right atria and the left and right ventricle. Valves separate the atria from the ventricles.

The heart’s walls consist of three layers of tissue:

• Myocardium: This is the muscular tissue of the heart.
• Endocardium: This tissue lines the inside of the heart and protects the valves and chambers.
• Pericardium: This is a thin protective coating that surrounds the other parts.
• Epicardium: This protective layer consists mostly of connective tissue and forms the innermost layer of the pericardium.

The rate at which the heart contracts depends on many factors, such as:

• activity and exercise
• emotional factors
• some medical conditions
• a fever
• some medications
• dehydration

At rest, the heart might beat around 60 times each minute. But this can increase to 100 beats per minute (bpm) or more.

Learn more information about a “normal” heart rate here.

Left and right sides

The left and right sides of the heart work in unison. The atria and ventricles contract and relax in turn, producing a rhythmic heartbeat.

Right side

The right side of the heart receives deoxygenated blood and sends it to the lungs.

• The right atrium receives deoxygenated blood from the body through veins called the superior and inferior vena cava. These are the largest veins in the body.
• The right atrium contracts, and blood passes to the right ventricle.
• Once the right ventricle is full, it contracts and pumps the blood to the lungs via the pulmonary artery. In the lungs, the blood picks up oxygen and offloads carbon dioxide.

Left side

The left side of the heart receives blood from the lungs and pumps it to the rest of the body.

• Newly oxygenated blood returns to the left atrium via the pulmonary veins.
• The left atrium contracts, pushing the blood into the left ventricle.
• Once the left ventricle is full, it contracts and pushes the blood back out to the body via the aorta.

Diastole, systole, and blood pressure

Each heartbeat has two parts:

Diastole: The ventricles relax and fill with blood as the atria contract, emptying all blood into the ventricles.

Systole: The ventricles contract and pump blood out of the heart as the atria relax, filling with blood again.

When a person takes their blood pressure, the machine will give a high and a low number. The high number is the systolic blood pressure, and the lower number is the diastolic blood pressure.

Systolic pressure: This shows how much pressure the blood creates against the artery walls during systole.

Diastolic pressure: This shows how much pressure is in the arteries during diastole.

Gas exchange

When blood travels through the pulmonary artery to the lungs, it passes through tiny capillaries that connect on the surface of the lung’s air sacs, called the alveoli.

The body’s cells need oxygen to function, and they produce carbon dioxide as a waste product. The heart enables the body to eliminate the unwanted carbon dioxide.

Oxygen enters the blood and carbon dioxide leaves it through the capillaries of the alveoli.

The coronary arteries on the surface of the heart supply oxygenated blood to the heart muscle.

Pulse

A person can feel their pulse at points where arteries pass close to the skin’s surface, such as on the wrist or neck. The pulse is the same as the heart rate. When you feel your pulse, you feel the rush of blood as the heart pumps it through the body.

A healthy pulse is usually 60–100 bpm, and what is normal can vary from person to person.

A very active person may have a pulse as low as 40 bpm. People with a larger body size tend to have a faster pulse, but it is not usually over 100 bpm.

Learn how to take the pulse here.

Share on PinterestA diagram of the heart’s valves.
Image credit: OpenStax College, Anatomy & Physiology, 2013

The heart has four valves to ensure that blood only flows in one direction:

• Aortic valve: This is between the left ventricle and the aorta.
• Mitral valve: This is between the left atrium and the left ventricle.
• Pulmonary valve: This is between the right ventricle and the pulmonary artery.
• Tricuspid valve: This is between the right atrium and right ventricle.

Most people are familiar with the sound of the heart. In fact, the heart makes many types of sound, and doctors can distinguish these to monitor the health of the heart.

The opening and closing of the valves are key contributors to the sound of the heartbeat. If there is leaking or a blockage of the heart valves, it can create sounds called “murmurs.”

To pump blood throughout the body, the muscles of the heart must work together to squeeze the blood in the right direction, at the right time, and with the right force. Electrical impulses coordinate this activity.

The electrical signal begins at the sino-atrial node, sometimes called the sinus, or SA, node. This is the heart’s pacemaker, and it sits at the top of the right atrium. The signal causes the atria to contract, pushing blood down into the ventricles.

The electrical impulse then travels to an area of cells at the bottom of the right atrium, between the atria and ventricles, called the atrioventricular, or AV, node.

These cells act as a gatekeeper. They coordinate the signal so that the atria and ventricles do not contract at the same time. There needs to be a slight delay.

From here, the signal travels along fibers, called Purkinje fibers, within the ventricle walls. The fibers pass the impulse to the heart muscle, causing the ventricles to contract.

There are three types of blood vessels:

Arteries: These carry oxygenated blood from the heart to the rest of the body. The arteries are strong, muscular, and stretchy, which helps push blood through the circulatory system, and they also help regulate blood pressure. The arteries branch into smaller vessels called arterioles.

Veins: These carry deoxygenated blood back to the heart, and they increase in size as they get closer to the heart. Veins have thinner walls than arteries.

Capillaries: These connect the smallest arteries to the smallest veins. They have very thin walls, which allow them to exchange compounds such as carbon dioxide, water, oxygen, waste, and nutrients with surrounding tissues.

The heart, blood, and blood vessels make up the circulatory, or cardiovascular, system.

Here, learn about some diseases that can affect this system.

The heart is essential to life — if it stops beating, blood will not reach the brain and other organs, and the person can die within minutes. This is called cardiac arrest.

If a person experiences cardiac arrest, they will be unable to speak or breathe, and they will have no heartbeat.

Anyone nearby should call 911 immediately and start cardiopulmonary resuscitation (CPR), pressing hard and fast with locked hands on the center of the person’s chest.

According to the Centers for Disease Control and Prevention (CDC), CPR can double or triple a person’s chance of survival after their heart stops.

Here, learn how to do CPR.

External Imaging | Atlas of Human Cardiac Anatomy

Anterior view of a “Heart-Lung Block” removed from a fixed cadaver. The
subclavian veins and arteries were kept intact connected to the great
vessels of the heart. This heart was enlarged and displaced the lower lobe
of the left lung.

Location:
the heart is positioned in the chest with 2/3 to the left of midline and
the inferior aspect is resting on the diaphragm. The apex of the heart is
pointing inferiorly and to the left. The media in this section display the
epicardial surface of the heart viewed either from the anterior, posterior
or left and right oblique aspects. Some of the media displays the heart in
a valentine position, with the long axis of the heart sitting in the
vertical plane. The rest of the images and videos display the heart
orientated in and attitudinally correct position, as the heart would be
viewed in the body, see anatomy
tutorial for more information.

Importance in cardiovascular diseases:
hypertrophic and dilated cardiomyopathies often alter the global structure
of the heart due to the heart changing size and shape during the progression
of the disease. Understanding how the heart is positioned in the body and
therefore where the relevant structures are is critically important for
cardiac surgery and bypass procedures.

Importance in device delivery:
epicardial pacing leads placed on both the atria and the ventricles will
often be used during trans-apical procedures and after bypass surgery to
control tachyarrhythmias and improve hemodynamic function in the presence
of arrhythmias.

How to take a photo in the shape of a heart – MOREREMONTA

Frames in the photo

Friends, meet new frames for photos in our photo editor. Now you have frames at your disposal in Luxury, Freehand and Paint styles. All frames are currently only available for round photos. But the day is not far off when you can crop a photo in the shape of a square or a heart and also impose a fashionable frame on the picture.

Crop photo in shape

Choose what shape you want to give your photo.Round or square picture, as well as many more different options for editing the shape of your photo. You can set any form of a photo, crop it for a social network post: facebook, instagram or vk. Decorate your feed with a non-standard photo and get well-deserved likes and reposts.

Text, stickers

Writing a wish on a photo or just making a homemade postcard is as easy as shelling pears. In our photo editor, you can choose the lettering font and color you need, place the text in the right place in the photo and at the right angle.You can also add funny stickers to the photo, highlighting your mood.

Filters, backgrounds

Apply filters to the picture: take a black and white photo, you can increase the contrast of the picture and improve the saturation of colors. An interesting move would be to add a blurred background to the photo or a bright juicy gradient to the background of the picture.

About Service

The “Rounding Tool” service was created for users who want to make a round avatar or picture online .With our service , you can round the corners of a photo online without Photoshop or other programs.

Privacy

This site does not collect personal information, data from your computer or IP. However, your images are publicly stored. If you do not want your pictures to be stored publicly, do not use this site.

Terms of Use

By using this site to round off the corners of an avatar or a picture, you acknowledge that we are not responsible for data errors, loss or inconsistencies in conversion.You may use this software at your own risk.

Suggestions for improvement, information about bugs, send to email

© 2019 Rounding tool, all rights reserved. Read the rounder blog

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Good afternoon, dear readers! You can give your favorite photos a special shape, make cute cards out of them.Pictures in the form of hearts look gentle. To give dynamics, highlight important details, triangles and asterisks are used. Square frames give an interesting effect. However, sometimes photographs take on completely special, unusual forms. Let’s try to figure out how you can change the outline of images on your phone and computer.

How to crop a heart-shaped photo on pc and phone

Photos in the form of hearts with cute, beloved faces look very gentle – as if some master created a postcard.It is not difficult to do this kind of pruning. To do this, you do not need to be able to draw or arm yourself with an eraser and carefully process the picture for several hours.

For framing in the shape of a heart on a pc, you can use the following programs:

• Microsoft powerpoint. Insert a photo, select “crop to shape” in the crop, find the heart. You can do the same in Microsoft word;
• Paint. In this application, you need to insert a picture and select the desired one in the “shapes” on the control panel;
• Coreldraw.First, create a path using the basic shapes. Then overlay it on the desired image and click “Exclude” in “Shaping”;
• in adobe photoshop you need to draw a heart on the photo and click “Clear” on the editing tab. Anything unnecessary will be excluded from the snapshot.

There are special applications for cropping on the phone:

• LiPix. Suitable for cropping on iPhone. Select a shape and then a photo. You can change the canvas by size, scale;
• PixArt.Powered by andro> You can also use online editors to make a heart out of a picture on your phone and computer.

Resources will help:

How to crop a freeform image

In Photoshop, Paint, Corel, LipPix, PixArt, online resources, images are cropped in the form of ovals, stars, triangles, squares. It is enough to choose a shape.

The function of forming an arbitrary contour is not available in all editors. She is present in adope photoshop, corel, paint.

These applications use 2 methods:

• the canvas is drawn, which will be used for trimming in the future;
• using the eraser to erase unnecessary parts of the image.

You can install eraser to process a picture on your phone.

Applications for PCs and phones, online resources allow you to quickly and easily give interesting shapes to photos, change them, make them original.

Open Science | MIPT investigated the nanoframework for heart cells –

Biophysicists have studied the structure of a substrate made of polymer nanofibers and the mechanism of its interaction with rat heart cells.These studies are carried out to create regenerative heart tissue. Scientists have found that muscle cells – cardiomyocytes – envelop nanofibers during growth, and connective tissue cells – fibroblasts – rely on nanofibers on one side. An article with the results was published in the journal Acta Biomaterialia. The work was carried out in the laboratory of biophysics of excitable systems of the Moscow Institute of Physics and Technology in collaboration with colleagues from the Federal State Budgetary Institution “National Medical Research Center for Transplantology and Artificial Organs named after V.I.VI Shumakov ”and the Institute of Theoretical and Experimental Biophysics of the Russian Academy of Sciences in the city of Pushchino.

Head of the Laboratory of Biophysics of Excitable Systems of the Moscow Institute of Physics and Technology Professor Konstantin Agladze says: “Using three independent methods, we have shown that cardiomyocytes, developing on a substrate of nanofibers, cover them from all sides and, in most cases, take the form of a ‘case’. Fibroblasts, on the other hand, have a more rigid structure and a smaller area of ​​interaction with nanofibers, since they rely on them only from one side.

The task of regenerative medicine is to restore damaged or lost organs of the human body. Tissue engineering is often the only way to restore the functions of such an important organ as the heart and to achieve a person’s rehabilitation. When scientists create tissue for “patches” of organs, it is necessary to investigate not only the properties of the tissue cells themselves, but also their interaction with the substrate, the surrounding nutrient solution and neighboring cells.

Correct support is the key to success

A fundamental role in the growth, development and formation of regenerating tissue is played by the substrate on which the cells are grown.Researchers grow heart cells on a matrix of polymer nanofibers. The latter can have different elasticity, electrical conductivity, and additional “smart” functions that allow, at a certain point in the development of cells, to release molecules of active substances. Nanofibers are designed to mimic the extracellular matrix – the outer surface of cells that provides structural support. In addition, through them, substances can be introduced for biochemical effects on the surrounding cells. Therefore, for the correct choice of the properties of nanofibers that bring an artificial system closer to structures in vivo (that is, “inside a living organism”), it is necessary to study the mechanism of their interaction at the nanoscale.

What’s under the microscope?

To determine the structure and mechanism of interaction between cardiac cells and nanofibers, three stages of research were carried out sequentially.

First, the scientists examined the structure of cardiomyocytes and fibroblasts grown on a nanofiber substrate using confocal laser scanning microscopy. This method is based on spot illumination of the smallest cell segments, giving images of micrometer parts, and gradual “scanning” along its entire perimeter.The structures of cardiomyocytes and fibroblasts (nucleus, components of the cytoskeleton of eukaryotic cells) and nanofibers were preliminarily labeled with fluorescent antibodies. The scientists obtained 3D images of the cells and saw that both types of cells are elongated along the nanofibers and are spindle-shaped (Fig. 1). However, the data obtained did not allow us to consider directly the surface of interaction of nanofibers with cells.

Figure 1. Images obtained using confocal laser scanning microscopy of cardiac cells when examining 1) cardiomyocyte, 2) fibroblast.Courtesy of the study authors.

Next, the researchers made ultrathin sections perpendicular to the direction of the nanofibers and took “photographs” using transmission electron microscopy. In the course of the study, an electron beam was passed through the cut samples, and a receiver located behind the object recorded the electrons that reached it. The number of electrons reaching the receiver depends on the properties and thickness of the material. Different cellular structures absorb the transmitted electron beam differently.Biophysicists saw that cardiomyocytes envelop the nanofibers from all sides, leaving them in the middle of the cell. However, in this case, the nanofibers are still completely separated from the cell cytoplasm by the membrane (Fig. 2).

Figure 2. Sectional image of a cardiomyocyte enveloping the substrate nanofiber. The image was obtained by transmission electron microscopy. 1 – cardiomyocyte, 2 – sectional nanofiber. Courtesy of the study authors.

Fibroblasts do not envelop the nanofibers, but only rely on them from one side.Also, electron micrographs show that fibroblast nuclei are less elastic compared to other cellular structures, which reduces cell plasticity and the ability to stretch along nanofibers (Fig. 3).

Figure 3. Cross-sectional image of the fibroblast obtained by transmission electron microscopy. 1 – fibroblast cell, 2 – nanofiber, er – endoplasmic reticulum, N – nucleus. Courtesy of the study authors.

Transmission electron microscopy made it possible to see what is happening on the section.Using probe tomography, scientists have created a full-fledged 3D model. Cells grown on a nanofiber substrate were cut into 120 nm thick plates. The structure of their surfaces was studied using a silicon probe and then virtually recreated (Fig. 4).

Figure 4. 3D-model of a cardiomyocyte enveloping nanofibers, obtained by probe tomography of cell nanosections. Courtesy of the study authors.

Increased adhesion of cardiomyocytes

Researchers have identified several important aspects of the mechanism of cell-substrate interaction.

Firstly, the increased mechanical adhesion – the adhesion of the nanofiber substrate and cardiomyocytes – contributes to the stability of the cells on the substrate. This means that the cardiac tissue (cardiomyocytes) will adhere more firmly to the substrate during growth. The fibroblast tissue will be less stable on the substrate.

The second thing that follows from the research results: the use of additional functions of the substrate, such as the emission of regulatory molecules (proteins that activate the process of cell growth) will also differ in cardiomyocytes and fibroblasts.In the case of cardiomyocytes enveloping nanofibers, the emitted substance will completely and without loss diffuse through the cell membrane into the cytoplasm. And for fibroblasts, it is necessary to take into account losses due to diffusion into the environment surrounding the cells during growth.

And third: cardiomyocytes completely envelop the nanofibers and isolate them from the fluid in which they develop. Therefore, the complete immersion of nanofibers into the cells of cardiomyocytes, which are responsible for the transmission of electromagnetic waves and, accordingly, for the contractions of the heart, will allow testing the electrical conductivity of the cells.

This study and further understanding of the mechanism of interaction of cardiac cells with a substrate will make it possible to successfully create nanofibers to form the necessary properties of cells and, accordingly, regenerative (regenerating) tissues.

This work was supported by a grant from the Ministry of Education and Science of the Russian Federation

90,000 Sepsis and septic shock: signs and diagnosis

Sepsis is a potentially life-threatening condition caused by the body’s response to infection.The body usually releases chemicals into the bloodstream to fight infection. Sepsis occurs when the body’s response to these chemicals is disrupted, causing changes that can disrupt the function of many organs.

If sepsis turns into septic shock, blood pressure drops sharply. This can lead to death.

Sepsis causes infections and can happen to anyone. Sepsis is most common and most dangerous for:

• Seniors
• Pregnant women
• Children under 1 year old
• People with chronic diseases such as diabetes, kidney, lung or cancer
• People with weakened immune systems

In the early stages, sepsis is treated with antibiotics and a large number of IVs to increase the chances of survival.

Signs and symptoms of sepsis

To be diagnosed with sepsis, you must have probable or confirmed infection and all of the following:

1. Change in mental status
2. The first (top) number in a blood pressure reading – also called systolic pressure – is less than or equal to 100 millimeters of mercury
3. Respiratory rate greater than or equal to 22 breaths per minute

Signs and symptoms of septic shock

Sepsis can progress to septic shock, when certain changes occur in the circulatory system and body cells that disrupt the delivery of oxygen and other substances to tissues.Septic shock is more likely to cause death than sepsis. To be diagnosed with septic shock, you must have a probable or confirmed infection and both of the following:

1. Drug requirement to maintain blood pressure above or equal to 65 millimeters of mercury.
2. High levels of lactic acid in your blood (serum lactate). Too much lactic acid in your blood means your cells are not using oxygen properly.

When to see a doctor

Sepsis is most common in people who are hospitalized or have recently been hospitalized. People in the intensive care unit are especially vulnerable to developing infections that can lead to sepsis. If you develop signs and symptoms of sepsis after surgery or after hospitalization, seek immediate medical attention.

Causes of sepsis

Although any type of infection – bacterial, viral, or fungal – can lead to sepsis, the most likely options are:

• Pneumonia
• Infection of the digestive system (which has affected the stomach and colon)
• Infection of the kidneys, bladder and other parts of the urinary system
• Blood infection (bacteremia)

Risk factors

Sepsis and septic shock are more common:

• At a very young age
• Old
• With a weakened immune system
• For diabetes or cirrhosis
• With frequent hospitalizations
• For wounds or injuries, burns
• When using invasive devices such as intravenous catheters or breathing tubes
• Previously received antibiotics or corticosteroids

Complications of sepsis

As sepsis develops, the blood supply to vital organs such as the brain, heart and kidneys is disrupted.Sepsis can cause blood clots to form in your organs, hands, feet, fingers and toes, leading to varying degrees of organ failure and tissue death (gangrene).

Most people recover from mild sepsis, but septic shock has a mortality rate of about 40 percent. Plus, an episode of severe sepsis can put you at greater risk for future infections.

marked red – Translation into Russian – examples English

These examples may contain rude words based on your search.

These examples may contain colloquial words based on your search.

The selected areas will be marked red .

Is all electrical equipment marked red switched off?

If you have a fleet of vehicles and wish to start using GPS tracking, please contact the nearest GPS tracking service that is marked red , green or blue on the map.

If you have your own vehicle fleet, and you want to start implementing a GPS or GLONASS monitoring system, contact the nearest satellite monitoring operator, which is designated on the map in red , green or blue.

[This dirt road is marked red in the footpath-marking map) Drive in this dirt road and after 1/2 km from the crossroads; park your vehicle in a big dirt parking area.

settlement) Zanoakh. At a distance of another half a kilometer (from the turn to this lane) there is a large unpaved area, where we park our car.

Suggest an example

Other results

Also in some partitions the last updates are marked as red .

The proxies that will not work will be marked in red color.

On each of these enlargements, the boundaries of the segment were marked in red , and the area was measured.

In each enlarged aerial image, marked the segment boundaries in red and measured its area.

Steadying on course marked in red .

Hitman, I am seeing armed Iraqis in civilian clothes in white pickups marked with red diamonds.

Hitman, I see armed Iraqis in civilian clothes in white pickup trucks with red diamonds on board.

In that case the pedestrian is being marked in red color and the driver of the car receives an audible warning.

In this case, pedestrian is marked in red and the driver of the vehicle receives an audible warning.

Just what is marked in red . here on the map.

Please find enclosed an amended matrix, in which updated information is marked in red color.

The operating device shall be marked in red .

In addition, the amendments suggested by the secretariat are marked in red .

All other electrical machines, appliances or equipment shall be marked in red .