What is the endocrine system. How does it affect our bodies. Which glands make up the endocrine system. What are the main functions of each endocrine gland. How do hormones regulate bodily functions.

The Endocrine System: An Overview of Chemical Messengers

The endocrine system plays a crucial role in maintaining the body’s homeostasis through a complex network of glands and hormones. These chemical messengers regulate various bodily functions, from metabolism and growth to mood and reproduction. Understanding the intricacies of this system is essential for comprehending how our bodies function on a daily basis.

What is the endocrine system?

The endocrine system is a network of glands that produce and secrete hormones directly into the bloodstream. These hormones act as chemical messengers, carrying information and instructions from one set of cells to another. Unlike the nervous system, which uses electrical impulses for rapid communication, the endocrine system employs a slower but more sustained approach to regulate bodily functions.

How do hormones work?

Hormones are released by endocrine glands into the bloodstream, allowing them to travel throughout the body. Once they reach their target cells, hormones bind to specific receptors, triggering a cascade of cellular responses. This process enables the endocrine system to influence almost every cell, organ, and function in our bodies.

The Major Glands of the Endocrine System

The endocrine system comprises several glands, each with unique functions and hormone productions. Let’s explore the primary glands that make up this intricate system:

• Hypothalamus
• Pituitary gland
• Thyroid gland
• Parathyroid glands
• Adrenal glands
• Pineal gland
• Pancreas
• Ovaries (in females)
• Testes (in males)

The Hypothalamus: The Bridge Between Nervous and Endocrine Systems

Located in the lower central part of the brain, the hypothalamus serves as a crucial link between the endocrine and nervous systems. It gathers information sensed by the brain, such as temperature, light exposure, and emotions, and sends it to the pituitary gland. This information influences the hormones produced and released by the pituitary.

The hypothalamus produces chemicals that control the release of hormones from the pituitary gland, effectively acting as a control center for many endocrine functions.

The Pituitary Gland: The Master Gland

Despite its small size (no larger than a pea), the pituitary gland is often referred to as the “master gland” due to its influence over other endocrine glands. Located at the base of the brain, it produces and releases several important hormones:

• Growth hormone: Stimulates bone and body tissue growth
• Prolactin: Activates milk production in breastfeeding women
• Thyrotropin: Stimulates the thyroid gland
• Corticotropin: Stimulates the adrenal glands
• Antidiuretic hormone: Regulates body water balance
• Oxytocin: Triggers uterine contractions during labor
• Endorphins: Reduce pain sensations

The pituitary gland also secretes hormones that signal the reproductive organs to produce sex hormones and controls ovulation and the menstrual cycle in women.

The Thyroid and Parathyroid Glands: Regulators of Metabolism and Calcium

The Thyroid Gland: Controlling Metabolic Rate

Shaped like a butterfly and located in the front part of the lower neck, the thyroid gland produces two main hormones: thyroxine and triiodothyronine. These hormones play a crucial role in regulating the body’s metabolic rate, affecting how quickly cells burn fuel for energy.

Thyroid hormones are particularly important for children and adolescents, as they contribute to bone growth and development, as well as the maturation of the brain and nervous system.

The Parathyroid Glands: Calcium Balance Specialists

Attached to the thyroid are four tiny glands called the parathyroids. These glands work together to release parathyroid hormone, which, in conjunction with calcitonin produced by the thyroid, controls calcium levels in the blood. This delicate balance is crucial for proper bone health, muscle function, and nerve signaling.

The Adrenal Glands: Stress Response and Homeostasis

The adrenal glands, situated atop each kidney, consist of two distinct parts, each with its own hormone production and function:

The Adrenal Cortex: Corticosteroid Production

The outer part of the adrenal glands, known as the adrenal cortex, produces hormones called corticosteroids. These hormones serve several vital functions:

• Regulating salt and water balance in the body
• Managing the body’s stress response
• Influencing metabolism
• Supporting immune system function
• Contributing to sexual development and function

The Adrenal Medulla: Catecholamine Secretion

The inner part of the adrenal glands, called the adrenal medulla, produces catecholamines such as epinephrine (also known as adrenaline). These hormones play a crucial role in the body’s “fight or flight” response, increasing blood pressure and heart rate during times of stress.

The Pineal Gland: Regulator of Circadian Rhythms

The pineal gland, a small endocrine gland located in the brain, is primarily responsible for producing melatonin. This hormone plays a crucial role in regulating the body’s circadian rhythms, also known as the sleep-wake cycle. The pineal gland’s melatonin production is influenced by light exposure, with levels typically rising in the evening and falling in the morning.

How does the pineal gland affect sleep patterns?

The pineal gland’s melatonin production helps signal to the body when it’s time to sleep and wake up. As darkness falls, melatonin levels rise, promoting feelings of sleepiness. Conversely, exposure to light suppresses melatonin production, helping to maintain alertness during daylight hours. This natural rhythm can be disrupted by factors such as jet lag, shift work, or excessive screen time before bed.

The Pancreas: A Dual-Function Organ

The pancreas is unique among endocrine glands as it serves a dual function, belonging to both the endocrine and digestive systems. As part of the endocrine system, the pancreas produces and secretes hormones directly into the bloodstream. Simultaneously, it creates and releases enzymes into the digestive tract, aiding in the breakdown of food.

Endocrine Functions of the Pancreas

The pancreas produces several hormones that play crucial roles in regulating blood sugar levels and digestion:

• Insulin: Lowers blood sugar by promoting glucose uptake by cells
• Glucagon: Raises blood sugar by stimulating the liver to release stored glucose
• Somatostatin: Regulates the release of other pancreatic hormones
• Pancreatic polypeptide: Helps regulate pancreatic secretions

The balance between insulin and glucagon is particularly important for maintaining stable blood glucose levels, which is essential for overall health and energy metabolism.

Reproductive Glands: Ovaries and Testes

The reproductive glands, ovaries in females and testes in males, are vital components of the endocrine system. These glands not only produce gametes (eggs and sperm) but also secrete sex hormones that play crucial roles in sexual development, reproduction, and overall health.

Ovaries: Female Reproductive Hormones

The ovaries produce several important hormones:

• Estrogen: Promotes the development of female secondary sexual characteristics and regulates the menstrual cycle
• Progesterone: Prepares the uterus for pregnancy and supports early pregnancy
• Inhibin: Helps regulate the production of follicle-stimulating hormone (FSH)

These hormones work in concert to control the menstrual cycle, support pregnancy, and influence various aspects of female health, including bone density and cardiovascular function.

Testes: Male Reproductive Hormones

The testes primarily produce testosterone, the main male sex hormone. Testosterone is responsible for:

• Development of male secondary sexual characteristics
• Sperm production
• Muscle mass and strength
• Bone density
• Sex drive

In addition to testosterone, the testes also produce small amounts of estrogen and inhibin, which help regulate sperm production and hormone balance.

Hormonal Balance and Endocrine Disorders

The endocrine system’s proper functioning relies on maintaining a delicate balance of hormones. Too much or too little of any hormone can lead to various health issues. Factors that can affect hormone levels include stress, infection, and changes in fluid and mineral balance in the blood.

Common Endocrine Disorders

When the endocrine system malfunctions, it can result in various disorders, including:

• Diabetes mellitus (Types 1 and 2)
• Thyroid disorders (hyperthyroidism and hypothyroidism)
• Adrenal insufficiency
• Growth hormone deficiency
• Polycystic ovary syndrome (PCOS)
• Cushing’s syndrome
• Hormone-related cancers

Many endocrine disorders can be effectively managed with medication, lifestyle changes, or hormone replacement therapy. Regular check-ups and blood tests can help detect and address hormonal imbalances before they lead to more severe health problems.

The Impact of Endocrine Disruptors

In recent years, there has been growing concern about endocrine disruptors – chemicals in the environment that can interfere with hormone function. These substances can be found in various products, including plastics, pesticides, and personal care items. Exposure to endocrine disruptors may lead to developmental issues, reproductive problems, and increased risk of certain cancers.

Researchers continue to study the long-term effects of endocrine disruptors and develop strategies to minimize exposure and mitigate their impact on human health.

The Future of Endocrine Research and Treatment

As our understanding of the endocrine system continues to grow, new avenues for research and treatment are emerging. Some exciting areas of development include:

• Personalized hormone therapy: Tailoring treatment plans based on an individual’s unique hormonal profile and genetic makeup
• Advanced diagnostic tools: Developing more sensitive and accurate methods for detecting hormonal imbalances and endocrine disorders
• Targeted drug delivery: Creating medications that can more precisely deliver hormones or hormone-regulating compounds to specific tissues or organs
• Endocrine system and aging: Investigating the role of hormones in the aging process and developing interventions to promote healthy aging
• Hormone-related cancer treatments: Exploring new therapies that target hormone-dependent cancers, such as certain types of breast and prostate cancer
• Environmental endocrinology: Studying the impact of environmental factors on the endocrine system and developing strategies to mitigate harmful effects

As research progresses, our ability to diagnose, treat, and prevent endocrine disorders will continue to improve, leading to better health outcomes and quality of life for individuals affected by hormonal imbalances.

The Role of Artificial Intelligence in Endocrine Research

Artificial intelligence (AI) and machine learning are increasingly being applied to endocrine research and clinical practice. These technologies have the potential to revolutionize how we understand and treat hormonal disorders by:

• Analyzing large datasets to identify patterns and correlations in hormone levels and health outcomes
• Predicting individual responses to hormone therapies based on genetic and environmental factors
• Optimizing treatment protocols for complex endocrine disorders
• Enhancing early detection of hormonal imbalances through advanced image analysis and biomarker identification

As AI technologies continue to evolve, they may become invaluable tools for endocrinologists and researchers, leading to more personalized and effective treatments for endocrine disorders.

Maintaining a Healthy Endocrine System

While some endocrine disorders are genetic or unavoidable, there are several steps individuals can take to support their endocrine health:

Lifestyle Factors for Endocrine Health

• Maintain a balanced diet rich in nutrients essential for hormone production
• Engage in regular physical activity to support hormone balance and metabolism
• Manage stress through relaxation techniques, meditation, or yoga
• Get adequate sleep to support proper hormone regulation
• Limit exposure to potential endocrine disruptors by choosing organic products and avoiding plastic containers when possible
• Stay hydrated to support overall endocrine function
• Avoid excessive alcohol consumption and quit smoking

Regular Health Check-ups

Regular medical check-ups and screenings are crucial for maintaining endocrine health. These appointments allow healthcare providers to monitor hormone levels, detect any imbalances early, and address potential issues before they become more serious. Depending on age, gender, and individual risk factors, your healthcare provider may recommend specific tests or screenings to assess endocrine function.

By understanding the complexities of the endocrine system and taking proactive steps to support hormonal balance, individuals can promote overall health and well-being throughout their lives. As research in this field continues to advance, we can look forward to even more effective strategies for maintaining optimal endocrine function and addressing hormonal disorders.

Endocrine System – Connecticut Children’s

Content

What Is the Endocrine System?

The endocrine system is made up of glands that make hormones. Hormones are the body’s chemical messengers. They carry information and instructions from one set of cells to another.

The endocrine (EN-duh-krin) system influences almost every cell, organ, and function of our bodies.

What Does the Endocrine System Do?

• Endocrine glands release

  hormones
  into the bloodstream. This lets the hormones travel to cells in other parts of the body.

• The endocrine hormones help control mood, growth and development, the way our organs work,

  metabolism
  , and reproduction.

• The endocrine system regulates how much of each hormone is released. This can depend on levels of hormones already in the blood, or on levels of other substances in the blood, like calcium. Many things affect hormone levels, such as stress, infection, and changes in the balance of fluid and minerals in blood.

Too much or too little of any hormone can harm the body. Medicines can treat many of these problems.

What Are the Parts of the Endocrine System?

While many parts of the body make hormones, the major glands that make up the endocrine system are the:

• hypothalamus
• pituitary
• thyroid
• parathyroids
• adrenals
• pineal body
• the ovaries
• the testes

The pancreas is part of the endocrine system and the digestive system. That’s because it secretes hormones into the bloodstream, and makes and secretes enzymes into the digestive tract.

Hypothalamus: The hypothalamus (hi-po-THAL-uh-mus) is in the lower central part of the brain. It links the endocrine system and nervous system. Nerve cells in the hypothalamus make chemicals that control the release of hormones secreted from the pituitary gland. The hypothalamus gathers information sensed by the brain (such as the surrounding temperature, light exposure, and feelings) and sends it to the pituitary. This information influences the hormones that the pituitary makes and releases.

Pituitary: The pituitary (puh-TOO-uh-ter-ee) gland is at the base of the brain, and is no bigger than a pea. Despite its small size, the pituitary is often called the “master gland.” The hormones it makes control many other endocrine glands.

The pituitary gland makes many hormones, such as:

• growth hormone, which stimulates the growth of bone and other body tissues and plays a role in the body’s handling of nutrients and minerals
• prolactin (pro-LAK-tin), which activates milk production in women who are breastfeeding
• thyrotropin (thy-ruh-TRO-pin), which stimulates the thyroid gland to make thyroid hormones
• corticotropin (kor-tih-ko-TRO-pin), which stimulates the adrenal gland to make certain hormones
• antidiuretic (an-ty-dy-uh-REH-tik) hormone, which helps control body water balance through its effect on the kidneys
• oxytocin (ahk-see-TOE-sin), which triggers the contractions of the uterus that happen during labor

The pituitary also secretes endorphins (en-DOR-fins), chemicals that act on the nervous system and reduce feelings of pain. The pituitary also secretes hormones that signal the reproductive organs to make sex hormones. The pituitary gland also controls

ovulation
and the menstrual cycle in women.

Thyroid: The thyroid (THY-royd) is in the front part of the lower neck. It’s shaped like a bow tie or butterfly. It makes the thyroid hormones thyroxine (thy-RAHK-sin) and triiodothyronine (try-eye-oh-doe-THY-ruh-neen). These hormones control the rate at which cells burn fuels from food to make energy. The more thyroid hormone there is in the bloodstream, the faster chemical reactions happen in the body.

Thyroid hormones are important because they help kids’ and teens’ bones grow and develop, and they also play a role in the development of the brain and nervous system.

Parathyroids: Attached to the thyroid are four tiny glands that work together called the parathyroids (par-uh-THY-roydz). They release parathyroid hormone, which controls the level of calcium in the blood with the help of calcitonin (kal-suh-TOE-nin), which the thyroid makes.

Adrenal Glands: These two triangular adrenal (uh-DREE-nul) glands sit on top of each kidney. The adrenal glands have two parts, each of which makes a set of hormones and has a different function:

1. The outer part is the adrenal cortex. It makes hormones called corticosteroids (kor-tih-ko-STER-oydz) that help control salt and water balance in the body, the body’s response to stress, metabolism, the immune system, and sexual development and function.
2. The inner part is the adrenal medulla (muh-DUH-luh). It makes catecholamines (kah-tuh-KO-luh-meenz), such as epinephrine (eh-puh-NEH-frun). Also called adrenaline, epinephrine increases blood pressure and heart rate when the body is under stress.

Pineal: The pineal (pih-NEE-ul) body, also called the pineal gland, is in the middle of the brain. It secretes melatonin (meh-luh-TOE-nin), a hormone that may help regulate when we sleep at night and wake in the morning.

Reproductive Glands: The gonads are the main source of sex hormones. In boys the male gonads, or testes (TES-teez), are in the scrotum. They secrete hormones called androgens (AN-druh-junz), the most important of which is

testosterone
(tess-TOSS-tuh-rone). These hormones tell a boy’s body when it’s time to make the changes associated with puberty, like penis and height growth, deepening voice, and growth in facial and pubic hair. Working with hormones from the pituitary gland, testosterone also tells a boy’s body when it’s time to make sperm in the testes.

A girl’s gonads, the ovaries (OH-vuh-reez), are in her pelvis. They make eggs and secrete the female hormones

estrogen
(ESS-truh-jen) and

progesterone
(pro-JESS-tuh-rone). Estrogen is involved when a girl starts puberty. During puberty, a girl will have breast growth, start to accumulate body fat around the hips and thighs, and have a growth spurt. Estrogen and progesterone are also involved in the regulation of a girl’s menstrual cycle. These hormones also play a role in pregnancy.

Pancreas: The pancreas (PAN-kree-us) makes insulin (IN-suh-lin) and glucagon (GLOO-kuh-gawn), which are hormones that control the level of glucose, or sugar, in the blood. Insulin helps keep the body supplied with stores of energy. The body uses this stored energy for exercise and activity, and it also helps organs work as they should.

What Can Help Keep the Endocrine System Healthy?

To help keep your child’s endocrine system healthy:

• Get plenty of exercise.
• Eat a nutritious diet.
• Go for regular medical checkups.
• Talk to the doctor before taking any supplements or herbal treatments.
• Let the doctor know about any family history of endocrine problems, such as diabetes or thyroid problems.

When Should I Call the Doctor?

Let the doctor know if your child:

• drinks a lot of water but is still thirsty
• has to pee often
• has frequent belly pain or nausea
• is very tired or weak
• is gaining or losing a lot of weight
• has tremors or sweats a lot
• is constipated
• isn’t growing or developing as expected

What makes up the endocrine system? |

Glands that produce and secrete hormones make up the endocrine system. These hormones are responsible for your body’s growth, metabolism, and sexual function and development. They are released into the bloodstream and affect the organs in your body.

The glands that make up the endocrine system are the:

• Hypothalamus,
• Pituitary,
• Thyroid,
• Parathyroids,
• Adrenals,
• Pineal gland,
• Reproductive organs, and
• Pancreas.

Hypothalamus

The hypothalamus regulates your hunger, metabolism and body temperature. It can be found in the lower central part of your brain.

The hormones secreted by the hypothalamus stimulate or suppress the release of hormones in the pituitary gland.

It also secretes somatostatin, which is a hormone that causes the pituitary gland to stop the release of growth hormones.

Pituitary gland

The pituitary gland is located at a position below the hypothalamus in the brain. It produces hormones that control many of the other endocrine glands’ functions.

It is possible to divide the pituitary gland can be divided into two lobes: the anterior lobe and the posterior lobe.

The anterior lobe produces hormones that are regulated by the hypothalamus:

1. Growth hormone, which stimulates bone and tissue growth.
2. Thyroid-stimulating hormone, which is responsible for stimulating the thyroid gland to produce thyroid hormones
3. Adrenocorticotropin hormone, which stimulates the adrenal gland to produce various steroid hormones
4. Luteinising hormone and follicle-stimulating hormone, which control sexual function and the production of oestrogen as well as progesterone or testosterone
5. Prolactin, which stimulates milk production in women

The posterior lobe produces hormones that are not regulated by the hypothalamus. These hormones are produced in the brain and carried to the pituitary gland through nerves.

1. Antidiuretic hormone, which controls your kidneys’ water loss
2. Oxytocin, which contracts the uterus when you are giving birth and stimulates milk production

Thyroid gland

The thyroid gland makes hormones that are responsible for regulating your body’s metabolism. It is situated in the lower front part of your neck. It also contributes to bone growth and the development of the brain as well as the nervous system in children. Thyroid hormones also help maintain blood pressure, heart rate, digestion, muscle tone and some reproductive functions.

Parathyroid glands

The parathyroid glands release hormones that regulate calcium levels in the blood and bone metabolism. It is embedded in the surface of the thyroid gland.

Adrenal glands

The adrenal glands consist of two parts:

1. The outer part (adrenal cortex), which produces hormones called corticosteroids. These hormones regulate your metabolism, salt and water balance, immune system and sexual function.
2. The inner part (adrenal medulla) produces hormones called catecholamines. These hormones help you cope with physical and emotional stress by increasing your heart rate and blood pressure.

Pineal gland

The pineal gland produces melatonin. This hormone regulates the body’s sleeping cycle. It is located in the middle portion of the brain.

Reproductive glands

The reproductive glands are the most familiar in the endocrine system. They are responsible for releasing sex hormones.

In men, their testes produce androgens, like testosterone. These hormones are responsible for men’s sexual development, the growth of facial and pubic hair, as well as sperm production.

In women, the ovaries produce oestrogen and progesterone, as well as ova. These hormones are responsible for the development of women’s breasts. They are also involved in women’s reproductive functions, like menstruation and pregnancy.

Pancreas

The pancreas can be divided into two parts:

1. The exocrine pancreas, which secretes digestive enzymes
2. The endocrine pancreas, which secretes insulin as well as glucagon. These hormones are responsible for regulating the level of glucose in your blood.

The pancreas is an organ situated at the back of your abdomen, behind your stomach.

Together, the various glands that make up the endocrine system release hormones that allow your body to function as it is supposed to. From reproductive functions to stress control to digestion – your endocrine system regulates it all.

Want to learn more regarding anatomy and physiology? Check out our Exercise Science Course for more information.

Endocrine Disorders – Symptoms, Causes, Treatments

Endocrine disorders are diseases related to the endocrine glands of the body. The endocrine system produces hormones, which are chemical signals sent out, or secreted, through the bloodstream. Hormones help the body regulate processes, such as appetite, breathing, growth, fluid balance, feminization and virilization, and weight control.

The endocrine system consists of several glands, including the pituitary gland and hypothalamus in the brain, adrenal glands in the kidneys, and thyroid in the neck, as well as the pancreas, ovaries and testes. The stomach, liver and intestines also secrete hormones related to digestion. Most common endocrine disorders are related to improper functioning of the pancreas and the pituitary, thyroid and adrenal glands.

Common endocrine disorders include diabetes mellitus, acromegaly (overproduction of growth hormone), Addison’s disease (decreased production of hormones by the adrenal glands), Cushing’s syndrome (high cortisol levels for extended periods of time), Graves’ disease (type of hyperthyroidism resulting in excessive thyroid hormone production), Hashimoto’s thyroiditis (autoimmune disease resulting in hypothyroidism and low production of thyroid hormone), hyperthyroidism (overactive thyroid), hypothyroidism (underactive thyroid), and prolactinoma (overproduction of prolactin by the pituitary gland). These disorders often have widespread symptoms, affect multiple parts of the body, and can range in severity from mild to very severe. Treatments depend on the specific disorder but often focus on adjusting hormone balance using synthetic hormones.

Modern treatment is generally quite effective for endocrine disorders, and severe consequences of endocrine dysfunction are rare. However, untreated endocrine disorders can have widespread complications throughout the body.

While endocrine disorders do not usually require hospitalization, in some cases they may lead to severe symptoms.
Seek immediate medical care (call 911) for serious symptoms, such as difficulty breathing, chest pain, or difficulty thinking clearly.

Seek prompt medical care if you are being treated for endocrine disorders and have persistent bothersome symptoms, as they may indicate a more serious condition.

Endocrine System | Biology for Majors II

Learning Outcomes

• Identify the structure and function of the endocrine system

The endocrine system is a control system of ductless glands that secrete hormones within specific organs. Hormones act as “messengers,” and are carried by the bloodstream to different cells in the body, which interpret these messages and act on them.

It seems like a far fetched idea that a small chemical can enter the bloodstream and cause an action at a distant location in the body. Yet this occurs in our bodies everyday of our lives. The ability to maintain homeostasis and respond to stimuli is largely due to hormones secreted within the body. Without hormones, you could not grow, maintain a constant temperature, produce offspring, or perform the basic actions and functions that are essential for life.

The endocrine system provides an electrochemical connection from the hypothalamus of the brain to all the organs that control the body metabolism, growth and development, and reproduction.

There are two types of hormones secreted in the endocrine system: Steroidal (or lipid based) and non-steroidal, (or protein based) hormones.

The endocrine system regulates its hormones through negative feedback, except in very specific cases like childbirth. Increases in hormone activity decrease the production of that hormone. The immune system and other factors contribute as control factors also, altogether maintaining constant levels of hormones.

Types of Glands

Exocrine Glands are those which release their cellular secretions through a duct which empties to the outside or into the lumen (empty internal space) of an organ. These include certain sweat glands, salivary and pancreatic glands, and mammary glands. They are not considered a part of the endocrine system.

Figure 1. Major endocrine glands. (Male left, female on the right.) 1. Pineal gland 2. Pituitary gland 3. Thyroid gland 4. Thymus 5. Adrenal gland 6. Pancreas 7. Ovary 8. Testis

Endocrine Glands are those glands which have no duct and release their secretions directly into the intercellular fluid or into the blood. The collection of endocrine glands makes up the endocrine system.

1. The main endocrine glands are the pituitary (anterior and posterior lobes), thyroid, parathyroid, adrenal (cortex and medulla), pancreas and gonads.
2. The pituitary gland is attached to the hypothalamus of the lower forebrain.
3. The thyroid gland consists of two lateral masses, connected by a cross bridge, that are attached to the trachea. They are slightly inferior to the larynx.
4. The parathyroid glands are four masses of tissue, two embedded posterior in each lateral mass of the thyroid gland.
5. One adrenal gland is located on top of each kidney. The cortex is the outer layer of the adrenal gland. The medulla is the inner core.
6. The pancreas is along the lower curvature of the stomach, close to where it meets the first region of the small intestine, the duodenum.
7. The gonads (ovaries and testes) are found in the pelvic cavity.

Hormones and Types

A hormone is a type of chemical signal. They are a means of communication between cells.

The endocrine system produces hormones that are instrumental in maintaining homeostasis and regulating reproduction and development. A hormone is a chemical messenger produced by a cell that effects specific change in the cellular activity of other cells (target cells). Unlike exocrine glands (which produce substances such as saliva, milk, stomach acid and digestive enzymes), endocrine glands do not secrete substances into ducts (tubes). Instead, endocrine glands secrete their hormones directly into the surrounding extra cellular space. The hormones then diffuse into nearby capillaries and are transported throughout the body in the blood.

The endocrine and nervous systems often work toward the same goal. Both influence other cells with chemicals (hormones and neurotransmitters). However, they attain their goals differently. Neurotransmitters act immediately (within milliseconds) on adjacent muscle, gland, or other nervous cells, and their effect is short-lived. In contrast, hormones take longer to produce their intended effect (seconds to days), may affect any cell, nearby or distant, and produce effects that last as long as they remain in the blood, which could be up to several hours.

Table 1 shows the major hormones, their target and their function once in the target cell.

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SIU SOM Histology ERG

Many of the body’s cells secrete substances which influence other cells,
either locally or at some distance.  Cells which are conspicuously specialized
for this function are called endocrine cells.  (The suffix -crine
refers to secretion; the prefix endo- tells us that the secretory product
stays inside the body.)   All endocrine cells share certain characteristics.

• Most obviously, endocrine cells are all specialized for secretion.  Their
  specific appearance depends on the nature of the secretory product and on
  the cellular machinery need to manufacture and store that product.  
• Also, their secretory products are secreted into interstitial fluid from
  whence they can diffuse into blood.  Therefore, endocrine secretion
  does not involve ducts but requires close proximity to blood vessels, usually
  either capillary networks or vascular sinusoids.  
• Endocrine cells are commonly arranged into cords or small clumps, with
  each cell closely associated with adjacent vessels.
• To faciliate diffusion of hormones into blood, vessels associated with
  endocrine glands have fenestrated endothelium.

The various endocrine cells of the human body are organized in a few distinctive
patterns.

Overview of Individual Endocrine Glands

The
pituitary gland (or hypophysis)
consists of two distinct parts, the anterior pituitary (adenohypophysis)
and the posterior pituitary (neurohypophysis).

The anterior pituitary appears glandular
(hence adenohypophysis), with clumps of epithelial cells with varying
staining properties.  Cells of several species each secrete one of
several hormones (e.g., GH, ACTH, FSH, LH, TSH, etc.)  Such secretion
from this “master gland” regulates most other endocrine glands
and is, in turn, regulated by factors secreted by hypothalamic neurons and
delivered to the anterior pituitary by the hypophyseal
portal vessels.  

The posterior pituitary consists of secretory
endings of axons from nerve cells (hence neurohypophysis) whose cell
bodies are located in the hypothalamus.  These secretory processes
of the posterior pituitary secrete oxytocin and ADH.

• Pituitary adenomas may be “benign” (i.e.,
  not malignant) but can nevertheless cause significant problems either from
  excess hormone production or from mass effect (e.g., crowding the optic
  chiasm).  For illustration, see WebPath.

The
thyroid consists of characteristic follicles,
each with a large lumen surrounded by a simple cuboidal epithelium.  The
appearance (as well as evolutionary origin) is that of an exocrine gland which
has lost its outlet so that secretory product accumulates in the follicles.
 Follicular cells store thyroglobulin in the follicles for subsequent
use in production and endocrine secretion of T3 (thyroxin) and T4.  Parafollicular
cells (C cells) produce calcitonin.

• For some examples of thyroid pathology, see WebPath
  (thyroiditis, inflammation), WebPath
  (Grave’s disease, hyperthyroid), and WebPath
  (goiter), or Milikowski & Berman’s Color Atlas of Basic Histopathology,
  pp. 452-461.

The
parathyroid consists of several discrete
glands, each organized into tangled curvilinear cords of chief cells.  These
cells secrete parathyroid hormone, which works in opposition to calcitonin
(from thyroid C cells) to regulate blood calcium levels.  

The
pancreatic islets are nests of endocrine cells
scattered within the pancreas.  Each islet consists of several cell types
which secrete insulin, glucagon, somatostatin, and pancreatic peptide.  The
cells are arranged into tangled cords.  

• Diabetes may result from
  immunological destruction of islet cells.  For images, see WebPath
  (diabetes I) and WebPath
  (diabetes II), or Milikowski & Berman’s Color Atlas of Basic Histopathology,
  p. 469.

The
adrenal consists of two distinct parts, an
outer cortex and an inner medulla.  

The cortex consists of cords of steroid-secreting
epithelial cells, separated by parallel sinusoids.  The cords are organized
into poorly defined zones.  From the outside inward, these zones secrete
mineral corticoids (e.g., aldosterone), glucocorticoids (e.g., cortisol),
and androgenic steroids.

• For images of tumors leading to Cushing’s disease,
  see WebPath
  (gross) and WebPath
  (microscopic), or Milikowski & Berman’s Color Atlas of Basic Histopathology,
  p. 466.
• For gross images of adrenal hyperplasia (e.g., subsequent
  to Cushing’s disease or ectopic ACTH production) and also
  adrenal atrophy, see WebPath.

The medulla consists of cells similar
to sympathetic neurons which secrete catecholamines (epinephrine and norepinephrine).

The
testis contains clusters of interstitial
Leydig cells which secrete testosterone.  

The
ovary includes steroid secreting cells of the
theca interna and of the corpus
luteum.  

The pineal consists
of pinealocytes, neuron-like cells which secrete melatonin.  Calcium
accumulation in the pineal gland makes this structure a useful landmark in
x-rays.  (Histology of the pineal will not be evaluated.  It is
mentioned here for completeness.)

According to Rene Decartes, it is through the pineal that
the soul controls the body.

http://www.siumed.edu/~dking2/erg/enguide.htm

Last updated:  31 March 2004 / dgk

How the Endocrine System Works

The endocrine system is made up of certain special glands and the hormones produced by those glands in the body. The hormones are important for instructing specific cells to produce particular actions in response to a stimulus or imbalance in the body. The glands are responsible to recognize the need for hormone secretion.

The hormones travel in the bloodstream to the cells where they act, and bind to the cells to initiate their effects.

These processes are tightly regulated by the endocrine system to maintain metabolic balance in the body. They are essential to keeping body functions normal. Such processes include cellular metabolism, sexual development and reproduction, homeostasis of sugar and other nutrients, and regulation of the heart rate, blood pressure, sleep cycles and digestion.

Endocrinologist testing woman patient at office – Image Copyright: NotarYES / Shutterstock

Components of the Endocrine System

The following are the chief glands of the endocrine system, which are involved in the secretion of the related hormones:

• Hypothalamus: also called the master gland of the endocrine system, it releases the following:
  
  • thyrotropin-releasing hormone (TRH)
  • growth hormone-releasing hormone (GHRH)
  • growth hormone inhibiting hormone (GHIH)
  • gonadotropin-releasing hormone (GnRH)
  • corticotropin-releasing hormone (CRH)
  • oxytocin
  • antidiuretic hormone (ADH)

• Posterior and anterior pituitary gland: though the pituitary gland appears to be a single gland, it is made up of two different units, which secrete quite different hormones regulating diverse physiologic processes:
  • thyroid stimulating hormone (TSH)
  • adrenocorticotropic hormone (ACTH)
  • follicle stimulating hormone (FSH)
  • luteinizing hormone (LH)
  • human growth hormone (HGH)
  • prolactin

Oxytocin and ADH are produced by the hypothalamic cells. The axons of these neurosecretory cells extend downwards to form the posterior pituitary gland, where these hormones are stored and released when required.

• Pineal gland: found in the brain, it secretes hormones like melatonin which regulate the circadian rhythm in response to light.
• Thyroid gland: this gland in the neck is essential for the proper function of almost all body tissues, releasing:
  • calcitonin
  • triiodothyronine (T3)
  • thyroxine (T4)

• Parathyroid glands: these are concerned with calcium metabolism and are embedded in the thyroid gland, secreting parathyroid hormone (PTH)
• Adrenal glands: these are situated like tiny caps on the kidneys, and secrete the stress hormones called glucocorticoids, the salt-water balance regulators called mineralocorticoids, and the male sex hormones, called the androgens. All these are from the adrenal cortex. As well, the adrenal produces the classic fight-fright-flight catecholamine hormones called epinephrine and norepinephrine, from the inner medulla.
• Pancreas: this is a large exocrine gland secreting pancreatic juice to digest our food, but contains numerous scattered cell clumps called the islets of Langerhans.  These are made up of endocrine alpha and beta cells that secrete the glucose-regulating hormones glucagon and insulin respectively.
• Digestive system: cells in the digestive tract secrete various hormones which modulate digestive functions, such as cholecystokinin (CCK), secretin, gastrin and ghrelin.
• Gonads: these are the primary sexual organs, which secrete testosterone, estrogens, and progesterone.
• Thymus: this gland in the neck releases the thymosins which mature the T-lymphocytes for immune function.
• Adipose tissue: fat cells throughout the body produce the hormone leptin. Low leptin levels encourage the body to enter ‘starvation mode’. Here it attempts to conserve energy by slowing down or avoiding all unnecessary activity, and to increase its intake of food by feelings of hunger.

Hormone, Receptor and Cell Interaction

An endocrine hormone is released by a specific gland and travels throughout the body in the bloodstream to reach its target cell, where it will exert a certain effect. Each hormone recognizes their target cells from the many other cells in the body by means of the receptors that exist on the cell, which they are able to bind to.

The receptor then initiates a series of chemical reactions within the cell to produce the intended effect of the hormone. For example, many endocrine hormones may stimulate the release of a chemical that induces or prevents the production of a certain gene.

After the action of the hormone, the release of the hormone from the endocrine gland must be regulated by a negative feedback loop to control the process and prevent the continuous and excessive activation of receptors.

Hormonal Regulation

Various processes in the endocrine system help to regulate the secretion of hormones and the resulting actions. This is essential for the body to maintain control over the action of the hormones. In other words, regulation is required to allow a hormone to initiate the intended reaction when needed and bring it to an end once the action has been completed.

For example, when the body is stressed the hypothalamus gland begins to secrete the corticotropin-releasing hormone (CRH) into the blood. This travels to the anterior pituitary gland to stimulate the release of adrenocorticotrophic hormone (ACTH). ACTH then travels in the blood to the adrenal glands, to stimulate the adrenal cortex cells which secrete the hormone cortisol.

Cortisol is responsible for stimulating the liver and skeletal muscles to increase the metabolism of glycogen (a storage form of glucose) so as to increase the blood glucose levels. The aim is to provide more energy as a response to the initial stimulus of stress.

When the body has adapted or reacted sufficiently to the stress and the body no longer requires more energy, the secretion of cortisol is cut off by a negative feedback loop. That is, the higher concentrations of the cortisol hormone in the blood ‘tell’ the hypothalamus that the action has been completed.

As a result, the hypothalamus ceases to secrete the corticotropin-releasing hormone and the production of cortisol is reduced.

Chemical Regulation

Chemicals can also regulate the release of hormones, such as when an endocrine gland responds to a change in concentration of a chemical in the body.

For example, the parathyroid hormone is responsible for regulating the levels of calcium in the body. When the calcium levels in the blood drop below a certain threshold, the parathyroid gland begins to secrete more parathyroid hormone, which helps to increase the concentration of calcium in the bloodstream.

Once the levels of calcium rise to sufficient levels to fulfil the normal cellular function in the body, the production of the hormone reduces accordingly.

Neural Regulation

The nervous system can also affect the release of hormones in the body.

For example, during the process of childbirth, the head of the fetus pushes against the cervix. The stimulation of the nerves in the cervix activates the release of the hormone oxytocin from the pituitary gland to increase the frequency and intensity of uterine contractions, and to release more oxytocin.

Unlike hormonal and chemical regulation, this is a positive feedback loop, where the reaction causes an increase in the initial stimulus and further response.

The hormone only ceases to be produced when the baby is born and the pressure on the cervix is relieved.  

References

Further Reading

5.3 Hormones and the Endocrine System – Human Biology

Theme 5: How Do We Control Our Fertility?

The endocrine system produces hormones that function to control and regulate many different body processes. The endocrine system coordinates with the nervous system to control the functions of the other organ systems. Cells of the endocrine system produce molecular signals called hormones. These cells may compose endocrine glands, may be tissues or may be located in organs or tissues that have functions in addition to hormone production. Hormones circulate throughout the body and stimulate a response in cells that have receptors able to bind with them. The changes brought about in the receiving cells affect the functioning of the organ system to which they belong. Many of the hormones are secreted in response to signals from the nervous system, thus the two systems act in concert to effect changes in the body.

Hormones

Maintaining balance within the body requires the coordination of many different systems and organs. One mechanism of communication between neighboring cells, and between cells and tissues in distant parts of the body, occurs through the release of chemicals called hormones. Hormones are released into body fluids, usually blood, which carries them to their target cells where they elicit a response. The cells that secrete hormones are often located in specific organs, called endocrine glands, and the cells, tissues, and organs that secrete hormones make up the endocrine system. Examples of endocrine organs include the pancreas, which produces the hormones insulin and glucagon to regulate blood-glucose levels, the adrenal glands, which produce hormones such as epinephrine and norepinephrine that regulate responses to stress, and the thyroid gland, which produces thyroid hormones that regulate metabolic rates. In addition, many organs in other body systems such as the reproductive system also secrete hormones and are therefore also part of endocrine system.

The level of hormones present in the blood is directly related to the magnitude of the responses, or actions, performed by the target cells.   For this reason, the body has evolved mechanisms to tightly regulate the level of hormone production for many hormones.  The release of hormones by endocrine cells is usually related to the amount of stimulus the receive.  A stimulus is any variable that can change the level of hormone secreted by an endocrine cell; common stimuli include nutrients, neurotransmitters, and even other hormones.  Most stimuli have a positive effect on endocrine cells, that is, with increasing amounts of stimuli increasing amounts of hormone are secreted. Some stimuli are negative regulators of endocrine cells, however.  When increased negative stimuli are present, hormone secretion decreases.  Many endocrine cells integrate inputs from multiple stimuli to regulate their level of hormone secretion.

How Hormones Work

Hormones cause changes in target cells by binding to specific cell-surface or intracellular hormone receptors, molecules embedded in the cell membrane or floating in the cytoplasm with a binding site that matches a binding site on the hormone molecule. In this way, even though hormones circulate throughout the body and come into contact with many different cell types, they only affect cells that possess the necessary receptors. Receptors for a specific hormone may be found on or in many different cells or may be limited to a small number of specialized cells. For example, thyroid hormones act on many different tissue types, stimulating metabolic activity throughout the body. Different types of cells can also respond to hormones in different ways.  For example, immune cell function is decreased when the hormone cortisol acts upon them, but cortisol causes liver cells to do something completely different, release glucose into the blood. Cells can have many receptors for the same hormone but often also possess receptors for different types of hormones.

Glossary

endocrine gland

an organ containing endocrine cells, cells that secrete hormones

hormone

a chemical secreted by an endocrine gland into body fluids (usually blood) that affects the function of target cells

hormone receptor

a molecule located on the surface of a cell, or inside it, that binds to a hormone; binding of a hormone to its receptor causes changes in the cell with the receptor

stimulus

a signal that increases or decreases the level of hormone secreted by an endocrine cell

target

a cell that expresses a hormone receptor, and changes its functions after the hormone binds to the receptor

Endocrine system – Endocrine system

Hormonal glands in the body

Endocrine system is a chemical system containing a feedback loop messenger of hormones released by the internal glands as an organism directly into the circulatory system, regulating distant target organs. In vertebrates, the hypothalamus is the neural control center for all endocrine systems. In humans, the main endocrine glands are the thyroid and adrenal glands.The study of the endocrine system and its disorders is known as endocrinology. Endocrinology is a branch of internal medicine.

The glands that signal each other in sequence are often referred to as an axis, such as the hypothalamus-pituitary-adrenal axis. In addition to the specialized endocrine organs mentioned above, many other organs that are part of other body systems have secondary endocrine functions, including bones, kidneys, liver, heart, and gonads.For example, the kidneys secrete the endocrine hormone erythropoietin. Hormones can be amino acid complexes, steroids, eicosanoids, leukotrienes, or prostaglandins.

The endocrine system can be contrasted with both exocrine glands, which secrete hormones outside the body, and paracrine signaling between cells at a relatively short distance. Endocrine glands have no ducts, are vascular, and usually have intracellular vacuoles or granules in which their hormones are stored.In contrast, exocrine glands, such as salivary glands, sweat glands, and gastrointestinal glands, have much fewer vessels and have ducts or cavities.

The word endocrine comes through the New Latin language from the Greek words ἔνδον, endon , “inside, inside,” and “ekrīnō” from εκκρινω, “to secrete.”

Composition

Basic endocrine systems

The human endocrine system consists of several systems that work through feedback loops.Several important feedback systems are mediated through the hypothalamus and pituitary gland.

Glands

Endocrine glands are glands of the endocrine system that secrete their products, hormones, directly into the intercellular spaces, and then are absorbed into the blood, and not through the duct. The main glands of the endocrine system include the pineal gland, pituitary gland, pancreas, ovaries, testes, thyroid, parathyroid, hypothalamus, and adrenal glands. The hypothalamus and pituitary gland are neuroendocrine organs.

The hypothalamus and the anterior pituitary gland are two of the three endocrine glands that are important for cell signaling. They are both part of the HPA axis, which is known to play a role in cell signaling in the nervous system.

Hypothalamus: The hypothalamus is a key regulator of the autonomic nervous system. The endocrine system has three sets of endocrine outlets, which include the magnocellular system, the parvocellular system, and autonomic intervention.Magnocellular is involved in the expression of oxytocin or vasopressin. Parvocellular is involved in the control of hormone secretion by the anterior pituitary gland.

Anterior pituitary gland: The main role of the anterior pituitary gland is to produce and secrete tropical hormones. Some examples of tropical hormones secreted by the anterior pituitary gland include TSH, ACTH, GH, LH, and FSH.

Cells

There are many types of cells that make up the endocrine system, and these cells usually make up the larger tissues and organs that function inside and outside the endocrine system.

Development

Function

Hormones

A hormone is any of a class of signaling molecules produced by car glands in multicellular organisms that are transported in the circulatory system to target distant organs to regulate physiology and behavior. Hormones have a diverse chemical structure, mainly 3 classes: eicosanoids, steroids, and amino acid / protein derivatives (amines, peptides and proteins).The glands that secrete hormones make up the endocrine system. The term “hormone” is sometimes expanded to include chemicals produced by cells that affect the same cell (autocrine or intracrine signaling) or neighboring cells (paracrine signaling).

Hormones are used for communication between organs and tissues for physiological regulation and behavioral activity such as digestion, metabolism, respiration, tissue function, sensory perception, sleep, excretion, lactation, stress, growth and development, movement, reproduction and mood.

Hormones affect distant cells by binding to specific receptor proteins in the target cell, which leads to a change in cell function. This can lead to cell-type responses that include rapid changes in the activity of existing proteins or slower changes in the expression of target genes. Amino acid-based hormones (amines and peptide or protein hormones) are water-soluble and act on the surface of target cells through signaling pathways; steroid hormones, being fat-soluble, pass through the plasma membranes of target cells to act inside their nuclei.

Signaling Cell

A typical way of signaling cells in the endocrine system is endocrine signaling, that is, using the circulatory system to reach distant target organs. However, there are other ways, such as paracrine, autocrine and neuroendocrine signaling. On the other hand, purely neurocrine signaling between neurons belongs entirely to the nervous system.

Autocrin

Autocrine signaling is a form of signaling in which a cell releases a hormone or chemical messenger (called an autocrine agent) that binds to autocrine receptors in the same cell, causing changes in the cells.

Paracrin

Some endocrinologists and clinicians include the paracrine system as part of the endocrine system, but there is no consensus. Paracrines act more slowly, affecting cells of the same tissue or organ. An example of this is somatostatin, which is secreted by some cells in the pancreas and targets other cells in the pancreas.

Juxtacrine

Jacstacrin signaling is a type of cell-to-cell communication that is transmitted through oligosaccharide, lipid, or protein components of the cell membrane and can affect either the emitting cell or directly adjacent cells.

This occurs between neighboring cells that have wide areas of closely spaced plasma membrane connected by transmembrane channels known as connexons. The gap between cells is usually 2 to 4 nm.

Clinical significance

Disease

Diseases of the endocrine system are common, including conditions such as diabetes mellitus, thyroid disease and obesity. Endocrine disease is characterized by improper regulation of hormone release (productive pituitary adenoma), inappropriate signaling (hypothyroidism), glandular absence (type 1 diabetes mellitus, decreased erythropoiesis in chronic renal failure), or structural enlargement of a critical site such as the thyroid gland (toxic multinodular goiter ).Hypofunction of the endocrine glands can result from loss of reserve, hyposecretion, agenesis, atrophy, or active destruction. Hyperfunction may result from hypersecretion, loss of suppression, hyperplastic or neoplastic changes, or hyperstimulation.

Endocrinopathies are divided into primary, secondary and tertiary. Primary endocrine disease suppresses the action of the underlying glands. Secondary endocrine disease indicates a problem with the pituitary gland.Tertiary endocrine disease is associated with dysfunction of the hypothalamus and its releasing hormones.

Since the thyroid gland and hormones are involved in signaling proliferation to distant tissues, for example, the estrogen receptor has been shown to be involved in some types of breast cancer. Endocrine, paracrine and autocrine signaling are involved in proliferation, one of the necessary stages of oncogenesis.

Other common diseases that result from endocrine dysfunction include Addison’s disease, Cushing’s disease, and Graves disease.Cushing’s disease and Addison’s disease are pathologies associated with dysfunction of the adrenal glands. Adrenal dysfunction can be caused by primary or secondary factors and can lead to hypercortisolism or hypocortisolism. Cushing’s disease is characterized by hypersecretion of adrenocorticotropic hormone (ACTH) due to a pituitary adenoma, which ultimately causes endogenous hypercortisolism by stimulating the adrenal glands. Some of the clinical signs of Cushing’s disease include obesity, moon face, and hirsutism.Addison’s disease is an endocrine disorder that results from hypocortisolism caused by adrenal insufficiency. Adrenal insufficiency is significant because it correlates with decreased ability to maintain blood pressure and blood sugar levels – a defect that can be fatal.

Graves’ disease is associated with an overactive thyroid gland that produces hormones T3 and T4. The effects of Graves disease range from excessive sweating, fatigue, heat intolerance, and high blood pressure to eye swelling causing redness, puffiness, and, in rare cases, decreased vision or double vision.

Other animals

The neuroendocrine system has been observed in all animals with a nervous system, and all vertebrates have a hypothalamic-pituitary axis. All vertebrates have a thyroid gland, which in amphibians is also critical for the transformation of larvae into adult form. All vertebrates have adrenal tissue, and mammals are unique in that they are organized into layers. All vertebrates have some form of the renin-angiotensin axis, and all tetrapods have aldosterone as their primary mineralocorticoid.

Additional images

• Female endocrine system

• Male endocrine system

See also

References

external links

Endocrine system

ENDOCRINE
SYSTEM

Endocrine
organs and nervous system regulate and
coordinate the functions of our body.Knowledge of the structure and functions of the endocrine
system is the basis for learning
humoral regulatory mechanisms.
Study of the histophysiology of endocrine
organs important for understanding disorders
humoral regulation that
essential for doctors of all specialties
and especially endocrinologists.

General
endocrine system characteristics

V
the composition of the endocrine system includes
highly specialized secretory
organs (organs with purely endocrine
secretion) or parts of organs (in the glands
with mixed function), as well as single
endocrine cells scattered over
various non-endocrine organs (lungs,
kidneys, digestive tube).The basis
most endocrine glands (as well as
exocrine) is epithelial
the cloth. However, a number of organs (hypothalamus,
posterior lobe of the pituitary gland, pineal gland, cerebral
adrenal substance, some
single endocrine cells) are
derivatives of nervous tissue (neurons
or neuroglia).

All
organs of the endocrine system produce
highly active and specialized
but the action of the substance is hormones. One and
the same endocrine gland can
produce different
action of hormones.At the same time, secretion
the same hormones can be carried out
different endocrine organs.
Morphological signs of endocrine
bodies are the presence of a group
highly specialized secretory
cells or one such cell,
producing biologically active
substances – hormones entering the blood
and lymph. Therefore, in the endocrine organs
there are no excretory ducts, and
endocrine cells are surrounded by dense
a network of lymphatic and circulatory
sinusoidal capillaries. In the endocrine
secretory hormone-producing system
cells can be arranged in groups,
strands, follicles or solitary
endocrinocytes.Hormones by chemical
are different in nature: protein (STH),
glycoprotein (TSH), steroid (bark
adrenal glands). Hormones in action
are divided into “triggers” and “hormones-executors”.
The “trigger” hormones include
central endocrine neurohormones
hypothalamic organs and tropic hormones
pituitary gland. “Hormones-executors”
peripheral endocrine glands or
target organs as opposed to “launchers”
have a direct effect
on the basic functions of the body: adaptation,
metabolism, growth, sexual function and
dr.

V
the body, there are two regulating
systems: nervous and endocrine.
Endocrine system activity in
ultimately regulated by the nervous
system. The connection between nervous and endocrine
the system is carried out through the hypothalamus
– the part of the brain, which is the highest
vegetative center. Its nuclei are formed
special neurosecretory neurons,
capable of producing not only
neurotransmitter neuramines (norepinephrine,
serotonin), like all neurons, but also
neurohormones, in particular liberins and
statins entering the bloodstream
channel and thus reaching
the anterior lobe of the pituitary gland.These neurohormones
are transmitters, switches
impulses from nervous to endocrine
system, on the adenohypophysis, stimulating with
with the help of the Liberins or, by oppressing through
statin production by endocrinocytes
the anterior lobe of the pituitary gland of triple hormones,
in turn affecting products
hormones by peripheral endocrine
glands. So humoral
by, transhypophyseal hypothalamus
regulates the activity of peripheral
endocrine organs – target organs,
endocrine cells which have
receptors for the corresponding hormones.Hypothalamic regulation of endocrine
glands can also be carried out parahypophysially
along the chains of efferent neurons. In his
feedback queue
endocrine glands are able to directly
react to your own hormones.
It should be noted that the regulatory role
the hypothalamus is controlled by higher
parts of the brain (limbic
system, pineal gland, reticular formation
etc.), the ratio of catecholamines,
serotonin, acetylcholine, and
endorphins and znkephalins produced by
special neurons in the brain.

Classification
organs of the endocrine system

1.
Central regulatory entities
endocrine system (neurosecretory
nuclei of the hypothalamus, pituitary gland, pineal gland).

2.
Peripheral endocrine glands:
pituitary-dependent (thyroid thyrocytes
glands, adrenal cortex) and
pituitary-independent (parathyroid
gland, thyroid calcitoninocytes
glands, adrenal medulla).

3.Organs with endocrine and non-endocrine
functions (pancreas, genital
glands, placenta).

4.
Single hormone-producing cells
(in the lungs, kidneys, digestive tube
and others) of nervous genesis and not nervous.

Organs
endocrine system

PYPOPHYSIS
consists of adenohypophysis epithelial
genesis (anterior lobe, middle lobe and
tubular part and neurohypophysis
neuroglial origin (posterior
share, funnel, stem).Anterior lobe
the pituitary gland is represented by epithelial
endocrinocytes located in groups
and strands, between which in a loose
connective tissue are located
sinusoidal blood capillaries
type. Endocrinocytes are divided into days
large groups: chromophilic with good
colored granules and chromophobic
with weakly staining cytoplasm and
not having granules. Among chromophilic
cells are distinguished basophilic with granules
containing glycoproteins and staining
basic dyes, and acidophilic
with large protein granules,
acidic dyes.Basophilic endocrinocytes (4-10%)
include several types (depending
from the hormone produced, see table
1 cells: thyrotropocytes – cells
polygonal, in their cytoplasm
contains small granules (80-150 nm),
oval or round gonadotrocytes
forms have granules (200-300 nm) and
eccentrically located nucleus, in
in the center of the cell – a light zone – “yard”
or macula (on the electronogram it is
Golgi apparatus). Corticotropocytes –
cells of irregular shape, contain
special spherical granules (200-250 nm).Acidophilic endocrinocytes (30-35%) have
well-developed granular
endoplasmic reticulum and subdivided
on:

somatotropocytes
with granules with a diameter of 350-400 nm and
lactotropocytes with larger granules
500-600 nm in the cytoplasm. Chromophobic or
the main cells (60%) are either
poorly differentiated reserve,
or cells in different functional
states. Hypothalamic regulation
adenohypophyseal hormone formation
carried out in a humoral way.
Superior pituitary artery in the area
medial eminence of the hypothalamus
decomposes into primary capillary
net.On the walls of these capillaries
end axons of the neurons of the middle
hypothalamus. Along the axons of these neurons
their neurohormones liberins and statins
enter the bloodstream. Primary capillaries
plexuses are collected in portal
vessels. The latter descend into the front
share and there disintegrate into a secondary
the capillary network from which the liberins
and statins diffuse to endocrinocytes
adenohypophysis.

Medium
the proportion of the pituitary gland in humans is poorly developed.
This lobe produces melanocytotropin
and lipotropin, which affects lipid
exchange.This share consists of epithelial
cells and pseudofollicles – cavities
with a secretion of protein or mucous
character.

Neurohypophysis
– the posterior lobe is represented by neuroglial
process cells – pituicites.
This part of the pituitary gland itself does not produce,
but only accumulates hormones (ADH, oxytocin)
neurons of the nuclei of the anterior hypothalamus
and neurosecretory cumulative
Herring’s little bodies. The latter are
the endings of the axons of the cells of these neurons
on the walls of sinusoidal capillaries
the posterior lobe of the pituitary gland.Neurohypophysis
refers to neurohemal organs,
accumulating hypothalamic
hormones. The posterior lobe of the pituitary gland is connected
with the hypothalamus pituitary pedicle and
makes up with him a single hypothalamic-pituitary
system.

EPIFIZ

Epiphysis
or pineal gland – formation
diencephalon cone-shaped
forms. The pineal gland is covered with connective tissue
capsule from which thin
septa with vessels and nerves dividing
organ into indistinct lobules.IN
organ lobules distinguish between two types of cells
neuroectodermal genesis:
secretory pinealocytes
(endocrinocytes) and supporting
glial cells (gliocytes) with scant
cytoplasm and compacted nuclei.
Pinealocytes are divided into two types: light
and dark. Light pinealocytes – large
process cells with homogeneous
cytoplasm. Dark cells have
granular cytoplasm (acidophilic or
basophilic granules). These two varieties
pinealocytes seem to represent
different functional states of one
cells.Pinealocyte processes, clavate
expanding, contacting numerous
sinusoidal blood capillaries.
The involution of the pineal gland begins at the age of 4-5
age. After 8 years of age in
pineal gland areas are found
calcified stroma (“cerebral
sand ”), but the function of the gland does not stop.
The human epiphysis is able to catch
light irritation and regulate
rhythmic processes in the body,
associated with the change of day and night.
The hormonal hormones produced by the pineal gland
factors – serotonin, which turns into
melatonin, antigonadotropin regulate
functions of the gonads through the hypothalamus
and eyes.Among the hormonal factors
produced by the pineal gland, there is a hormone,
increasing the level of potassium in the blood.

THYROID
IRON

Consists
of two lobes connected to each other
part of a gland called the isthmus.
Outside, the gland is covered with connective tissue
capsule from which thin
interlayers with vessels dividing the organ
into slices. The main part of the parenchyma
lobules make up its structural and functional
units – follicles. These are bubbles
the wall of which consists of follicular
endocrinocytes – thyrocytes.Thyrocytes
– cubic epithelial cells
forms (with normal function) secreting
iodine-containing hormones – thyroxine and
triiodothyronine, affecting the main
exchange. The follicles are filled with colloid
(a viscous liquid containing thyroglobulia).
Outside, the follicle wall is closely connected
with a network of blood and lymph
capillaries. With hypothyroidism
glands thyrocytes are flattened, colloid
thickened, follicle size
increases, and, conversely, with hyperfunction
thyrocytes take prismatic
shape, the colloid becomes more liquid
and contains numerous vacuoles. IN
the secretory cycle of the follicle is distinguished
a production phase and a hormone elimination phase.
For the production of thyroxine,
iodides, amino acids, including tyrosine,
carbohydrate components, water, absorbable
thyrocytes from the blood. In the endoplasmic
the network of thyrocytes forms a polypeptide
chain of thyroglobulin, to which in
complex Golgi join
carbohydrate components. Blood iodides with
by means of peroxidases thyrocytes are oxidized
into atomic iodine. At the border of thyrocytes
and the follicle cavity is turned on
iodine atoms to tyrosine polypeptide
chains of thyroglobulin.As a result
mono- and diiodotyrosines are formed, and
further of them – tetraiodothyronine –
thyroxine and triiodothyronine. Elimination phase
proceeds with the reabsorption of the colloid by
phagocytosis of colloid fragments –
thyroglobulin by pseudopodia of thyrocytes
with strong activation of the gland. Then
phagocytosed fragments under
exposure to lysosomal enzymes
undergo proteolysis and released
from thyroglobulin iodothyronine buy
from thyrocyte to blood capillaries,
surrounding the follicle. Moderate activity
the thyroid gland is not accompanied
phagocytosis of the colloid.In this case
proteolysis is observed in the follicle cavity
and pinocytosis of proteolysis products
thyrocyte. In the connective tissue
there are stroma between follicles
small clusters of epithelial
cells (interfollicular islets),
are the source of development of new
follicles. As part of the follicle wall
or in interfollicular islets
light cells of the neural
origin – parafollicular
endocrinocytes or calcitoninocytes
(K-cells). These endocrinocytes have
cytoplasm in addition to neuraminic granules
(serotonin, norepinephrine) specific
coarseness associated with production
protein hormones – calcitonin,
lowering the level of Ca in the blood, and
somatostatin.The production of these hormones,
unlike thyroxine products, it does not
is associated with the absorption of iodine and does not depend
from thyrotropic hormone of the pituitary gland.
K-cell granules stain well
osmium and silver.

PERIOCIATE
IRON

Parenchyma
organ is represented by strands of epithelial
cells – parathyrocytes. Between them in
interlayers of connective tissue
numerous capillaries are located.
Distinguish between the main – light with inclusions
glycogen and dark parathyrocytes, as well
oxyphilic parathyrocytes with numerous
mitochindria.In the main cells
the cytoplasm is basophilic, with large
grains. Acidophilic cells are considered
aging forms of the main ones. Parathyroid hormone
parathyroid and calcitonin
thyroid glands are antagonists,
they maintain calcium homeostasis
in organism. Parathyrin production
has a hypercalcemic effect
and does not depend on pituitary hormones.

ADRENALS

Paired
organs consist of the external cortical
substance and internal cerebral
substances.In the cortical substance, there are
three zones of epithelial cells: glomerular,
mineralocorticoid-producing
hormone aldosterone, which affects
water-salt metabolism, for sodium retention
in organism; beam, producing
glucocorticoids that affect metabolism
carbohydrates, proteins, lipids, depressing
inflammation and immunity;
mesh zone – producing genital
hormones, androgens, estrogens, progesterone.
The glomerular zone located under
capsule, formed by strands of flattened
endocrinocytes forming clusters
– glomeruli.In the cytoplasm of these cells
few lipid inclusions. Destruction
this zone leads to death. Products and services
there are practically no hormones in this zone
depends on pituitary hormones. Under
the glomerular zone has a sudanophobic
lipid-free layer. Beam
the zone is the widest and consists of strands
cubic cells containing many
lipid inclusions, when dissolved
which the cytoplasm becomes “spongy”.
The cells themselves are called
spongiocytes. In the beam zone are distinguished
two types of cells: light and dark,
which are different functional
states of the same endocrinocytes. The mesh area is represented by branched
strands of small secretory cells,
forming a network in the loops of which
an abundance of sinusoidal capillaries. Beam
and reticular adrenal cortex
are pituitary-dependent zones. For
adrenal cortex,
producing steroid hormones,
good development of agranular
endoplasmic reticulum and mitochondria
with twisted, branching cristae.
The adrenal medulla is
derived from nerve cells. His
chromaffinocyte or brain cells
endocrinocytes are divided into light –
epinephrocytes that produce adrenaline,
and dark – norepinephrocytes producing
norepinephrine.These cells regenerate
oxides of chromium, silver, osmium. Hence their
names – chromaffinic, osmiophilic,
argyrophilic. Chromaffinocytes secrete
adrenaline and norepinephrine in the surrounding
their numerous blood vessels,
among which there are especially many venous
sinusoids. Brain activity
substance does not depend on pituitary hormones
and is regulated by nerve impulses. IN
leaving the body from stressful conditions
adrenal cortex and medulla
with their hormones participate together.

Endocrine system

Endocrine system

Endocrine system

In the sanatorium “Belokurikha”, the treatment of diseases of the endocrine system, nutritional disorders, metabolic disorders is carried out. Professional literacy of specialists is complemented by the possibility of a diagnostic base of sanatoriums.

The Ministry of Health’s own work experience and statistics states that autoimmune thyroiditis accounts for almost 30% of the total number of thyroid diseases.This disease usually manifests itself in people aged 40-50 years, although in recent years the disease has become “younger” and is increasingly diagnosed in young people, and sometimes in children.

Mineral water of the Belokurikha resort, with its immunomodulatory effect, allows you to control the process of inflammation in the thyroid gland, which has been proven by the scientific work of the resort’s doctors.

There is a “School of Health” where classes are taught by an endocrinologist, a nutritionist, and a psychotherapist.

Readings:

• Diffuse toxic goiter 1-3 degrees in euthyroid state or mild thyrotoxicosis, subclinical thyrotoxicosis

• Chronic inflammatory diseases of the thyroid gland (non-tuberculous etiology) with an enlargement of the gland of 0-1 degrees with euthyroidism, postponed subacute thyroiditis, chronic autoimmune thyroiditis, diffuse form in the euthyroid state and with hypothyroidism, in the stage of compensation

• Iodine deficiency states with an enlargement of the thyroid gland 0-1 degree in a state of euthyroidism, mild hypothyroidism

• Diabetes mellitus type 1 and 2, mild and moderate, in a state of stable compensation, without a tendency to ketoacidosis

• Primary obesity, exogenous-constitutional grade 1-3 without decompensation of the cardiovascular system or with circulatory failure not higher than grade 1

• Disorders of lipoprotein metabolism (dyslipidemia)

• Gout (violation of uric acid metabolism)

Procedures:

• Mineral nitrogen-siliceous low-radon baths

• Carbon dioxide dry baths

• Artificial baths (iodine-bromine, marine, coniferous, panto-magnesium)

• Diet therapy

• Drinking treatment with mineral medicinal table water “Belokurikhinskaya Vostochnaya-2”, “Zavyalovskaya”

• Manual massage or hydromassage

• Healing showers (“Charcot”, “Vichy”, circular, rain shower)

• Pool + saunas complex

• Mud therapy

• Lymphatic drainage of the lower extremities

• Physiotherapy (electrosleep, electrophoresis, darsonvalization, magnetic laser therapy, magnetotherapy).

• Psychotherapy (individual and group lessons)

• Reflexology

• Physiotherapy exercises, gym; terrainkurs, dosed walking routes

• Hirudotherapy (paid)

• Ozone therapy (paid)

• Speleotherapy

Survey:

• Consultations of narrow specialists: nutritionist, endocrinologist, cardiologist, psychotherapist, reflexologist, ophthalmologist, surgeon.

• Biochemical blood test (lipid profile, glycemic profile)

• Determination of glycosylated hemoglobin

• Examination of the fundus

• Bioimpedansometry and other functional studies

• Densitometry – determination of bone density (paid)

• Blood test for hormones: thyroid gland, pituitary gland, gonads (paid)

Contraindications:

• Diffuse toxic goiter with severe thyrotoxicosis, thyrotoxic heart with arrhythmias

• Severe hypothyroidism

• Malignant tumors of the endocrine glands and conditions after surgical treatment

• Severe diabetes mellitus with frequent hypoglycemic coma, ketoacidosis

• Obesity with symptoms of cardiovascular failure stage 2

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90,000 Consultation with an endocrinologist – make an appointment with an endocrinologist – prices

The endocrine system regulates the activity of internal organs and is represented by glands and specialized cells that produce hormones . The main organs of the endocrine system include the thyroid and parathyroid glands, the pituitary gland and the hypothalamus, the islet apparatus of the pancreas, the adrenal glands, and the sex glands.Each gland produces a complex of hormones that are involved in all types of metabolism, regulate changes in fluid balance, blood pressure, energy storage and use, sexual development, hair growth, hematopoiesis, and muscle development.

Violation in any link of endocrine regulation leads to a change in the functioning of almost all body systems. Such, at first glance, nonspecific complaints such as weakness, decreased performance, hair loss, deterioration of the skin condition, menstrual irregularities, extinction of sexual desire, weight change, are often symptoms of endocrine pathology. Therefore, the work of endocrinologists is closely related to many areas of medicine: therapy, gynecology, urology, ophthalmology, gastroenterology, etc.

It is especially important to assess the endocrine status in women planning pregnancy , as well as during pregnancy, since the presence of latent disorders can have an adverse effect not only on the health of the mother, but also on the unborn child.

Diseases of the endocrine glands, as a rule, have a severe and prolonged course, therefore it is necessary to identify them as early as possible, to prevent or prevent further development in a timely manner.Modern methods of functional and topical diagnostics, as well as all types of laboratory tests that are used in the MEDI clinic, help the endocrinologist in making an accurate diagnosis.

It is known that in the development of diseases of the endocrine glands, a significant role is played by hereditary predisposition and adverse effects of the external environment. Therefore, in assessing the risks of developing endocrine diseases, regular preventive examinations play a special role.

After establishing the final diagnosis for each patient, the endocrinologist draws up an individual treatment regimen.Most endocrine diseases have a chronic course, therefore, after stabilization of the condition, the endocrinologist conducts preventive monitoring of patients according to an individual program. This allows you to reduce the risk of severe complications, improve the quality of life and will be the key to active longevity.

Endocrine surgery

Scientific and practical medical peer-reviewed journal “Endocrine Surgery” – the first periodical in Russia devoted to the problems of diagnosis and surgical treatment of various diseases of the endocrine system.This scientific and practical publication examines the medical and technical issues of surgical approaches to the treatment of not only endocrine diseases, but also the problems of surgical treatment of complications of diabetes mellitus, in particular, diabetic foot syndrome, diabetic ophthalmopathy, etc.

The success of the treatment of diseases in this area depends on the close interaction of doctors of different medical specialties – endocrinologists, surgeons, oncologists, radiologists, pathomorphologists, anesthesiologists-resuscitators, geneticists – using the most modern high-tech methods of diagnosis, treatment and rehabilitation.The journal “ Endocrine Surgery ” aims to collect and summarize the opinions of all these specialists on its pages, but at the same time guarantees strict selection criteria for articles based on the principles of evidence-based medicine and international standards.

The need to publish the journal “ Endocrine Surgery ” is due to a number of factors. This is a huge number of patients in need of specialized medical care, and the emergence of a large number of specialists involved in the surgery of endocrine organs.At the same time, today in our country there are no industry standards for treatment, as well as patient registers.

The main sources that guide specialists in the treatment of endocrine diseases are various manuals on surgery, endocrinology and oncology, which often carry conflicting and mutually exclusive information. The practice of developing consensus decisions as new information is obtained and serious changes in the diagnosis and treatment of diseases, adopted in many professional associations, have not yet taken root in Russia.In this regard, the journal “ Endocrine Surgery ” focuses on the clinical recommendations of international associations on topical problems of endocrine surgery, reviews the most interesting publications of foreign literature based on the principles of evidence-based medicine.

90,000 Planning pregnancy for endocrine pathologies

The most common disorders of the endocrine system at the stage of pregnancy planning are:

Hyperprolactinemia – increased production of the hormone prolactin by the pituitary gland. With hyperprolactinemia, the ovulatory cycle is disrupted (the egg does not mature). Elimination of these disorders is possible with the appointment of drugs that block the production of the hormone prolactin. This is one of the causes of infertility, which in modern conditions can be successfully eliminated.

Hyperandrogenism – increased production of androgens (male sex hormones) by the adrenal glands or ovaries. With this pathology, there is a violation of menstrual and reproductive function, a disorder of metabolic processes, cosmetic defects.For the appointment of therapy aimed at reducing the production of androgens, the joint work of an endocrinologist and a gynecologist will be required. The situation is reversible with the correct selection of drugs.

Polycystic ovarian syndrome (PCOS) is one of the manifestations of hyperandrogenism against the background of malfunctioning of the ovaries or other endocrine glands (pituitary gland, hypothalamus, thyroid gland, adrenal glands). PCOS causes menstrual irregularities and, as a result, infertility.

Autoimmune thyroiditis (AIT) – disruption of the thyroid gland.Unsurprisingly, the thyroid gland is directly related to the reproductive system. With changes in the functioning of the thyroid gland, a violation of the menstrual cycle is observed, which can cause infertility or miscarriage. With careful diagnosis and selection of adequate hormone therapy, this problem can be solved.

At the Lapino Clinical Hospital, we approach the solution of the problem of planning pregnancy with endocrine pathology in a complex manner. Our team has first-class specialists: endocrinologists, gynecologists, reproductologists who can diagnose, select adequate therapy and lead a woman to a long-awaited pregnancy.

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