How does the endocrine system work. What are the main functions of hormones in the body. Which glands make up the endocrine system. How do hormones affect metabolism, growth, and reproduction. What happens when hormone levels are imbalanced.

The Fundamentals of the Endocrine System

The endocrine system is a complex network of glands and organs that produce and secrete hormones directly into the bloodstream. These chemical messengers play a crucial role in regulating various bodily functions, from metabolism and growth to reproduction and mood. Understanding the intricacies of this system is essential for maintaining overall health and well-being.

What exactly are hormones? Hormones are specialized molecules that act as the body’s chemical messengers. They travel through the bloodstream to reach target tissues and organs, where they trigger specific responses. Unlike the nervous system, which provides rapid, short-term control of bodily functions, the endocrine system exerts its influence more gradually, often over extended periods.

Key Components of the Endocrine System

• Hypothalamus
• Pituitary gland
• Thyroid gland
• Parathyroid glands
• Adrenal glands
• Pancreas
• Reproductive glands (ovaries in females, testes in males)

Each of these glands produces specific hormones that regulate various physiological processes. The intricate balance of these hormones is essential for maintaining homeostasis and optimal bodily function.

Hormones: The Body’s Chemical Messengers

Hormones are the workhorses of the endocrine system, carrying out a wide array of functions throughout the body. These chemical messengers are produced by specialized cells within endocrine glands and released directly into the bloodstream. From there, they travel to target tissues and organs, where they bind to specific receptors and trigger cellular responses.

What makes hormones so unique? Unlike neurotransmitters, which act quickly and locally, hormones can affect cells throughout the body and exert their influence over extended periods. This allows for long-term regulation of various physiological processes, including:

• Growth and development
• Metabolism
• Sexual function and reproduction
• Mood and behavior
• Stress response
• Blood sugar regulation
• Calcium homeostasis

The precise balance of hormones in the body is crucial for maintaining overall health. Even small fluctuations in hormone levels can have significant impacts on various bodily functions.

The Hypothalamus and Pituitary: Master Regulators of the Endocrine System

At the core of the endocrine system lies the hypothalamus-pituitary axis, a complex interplay between two key structures in the brain. The hypothalamus, located deep within the brain, serves as a crucial link between the nervous system and the endocrine system. It produces releasing and inhibiting hormones that control the function of the pituitary gland, often referred to as the “master gland” of the endocrine system.

How does this intricate system work? The hypothalamus monitors various physiological parameters and responds by secreting specific hormones. These hormones travel to the pituitary gland, where they stimulate or inhibit the release of pituitary hormones. The pituitary hormones, in turn, act on other endocrine glands throughout the body, regulating their function and hormone production.

Key Hormones Produced by the Hypothalamus

• Corticotropin-releasing hormone (CRH)
• Thyrotropin-releasing hormone (TRH)
• Gonadotropin-releasing hormone (GnRH)
• Growth hormone-releasing hormone (GHRH)
• Somatostatin

Important Pituitary Hormones

• Adrenocorticotropic hormone (ACTH)
• Thyroid-stimulating hormone (TSH)
• Follicle-stimulating hormone (FSH)
• Luteinizing hormone (LH)
• Growth hormone (GH)
• Prolactin

This hierarchical control system allows for precise regulation of hormone production throughout the body, ensuring that physiological processes are finely tuned to meet the body’s changing needs.

The Thyroid and Parathyroid Glands: Metabolism and Calcium Regulation

The thyroid and parathyroid glands play crucial roles in regulating metabolism and calcium homeostasis. Located in the neck, these glands produce hormones that have far-reaching effects on various bodily functions.

How does the thyroid gland influence metabolism? The thyroid gland produces two main hormones: thyroxine (T4) and triiodothyronine (T3). These hormones regulate the body’s metabolic rate, influencing how quickly cells convert nutrients into energy. Thyroid hormones affect nearly every organ in the body, controlling heart rate, body temperature, and even cognitive function.

The thyroid gland requires iodine to produce its hormones, which is why iodine deficiency can lead to thyroid disorders. In many countries, iodine is added to salt to prevent deficiency-related conditions.

Key Thyroid Hormones

• Thyroxine (T4)
• Triiodothyronine (T3)
• Calcitonin

What role do the parathyroid glands play? The parathyroid glands, four small glands located behind the thyroid, produce parathyroid hormone (PTH). This hormone is essential for maintaining proper calcium levels in the blood and bones. PTH works in concert with calcitonin, a hormone produced by the thyroid gland, to regulate calcium homeostasis.

When blood calcium levels drop, the parathyroid glands secrete PTH, which acts to increase calcium levels by:

• Stimulating bone resorption, releasing calcium from bone tissue
• Enhancing calcium absorption in the intestines
• Increasing calcium reabsorption in the kidneys

Conversely, when blood calcium levels rise, the thyroid gland releases calcitonin, which opposes the effects of PTH and helps lower blood calcium levels.

The Adrenal Glands: Stress Response and Steroid Hormone Production

The adrenal glands, located atop the kidneys, play a vital role in the body’s stress response and the production of various steroid hormones. These small but powerful glands are divided into two distinct regions: the adrenal cortex and the adrenal medulla, each producing different types of hormones.

How do the adrenal glands respond to stress? When the body experiences stress, whether physical or psychological, the adrenal glands spring into action. The adrenal medulla releases catecholamines, primarily epinephrine (adrenaline) and norepinephrine, which trigger the “fight or flight” response. This rapid reaction prepares the body to deal with immediate threats by increasing heart rate, blood pressure, and blood sugar levels.

Key Hormones Produced by the Adrenal Cortex

• Cortisol (the primary stress hormone)
• Aldosterone (regulates sodium and potassium balance)
• Androgens (precursors to sex hormones)

What is the role of cortisol in the body? Cortisol, often referred to as the “stress hormone,” plays a crucial role in the body’s long-term stress response. It helps regulate metabolism, blood sugar levels, and immune function. Cortisol levels typically follow a diurnal rhythm, peaking in the morning and gradually declining throughout the day.

In addition to its stress-related functions, cortisol also:

• Helps regulate blood pressure
• Influences memory formation
• Supports fetal development during pregnancy
• Modulates inflammation in the body

The adrenal glands also produce small amounts of sex hormone precursors, which can be converted to androgens, estrogens, and other steroid hormones in various tissues throughout the body. This contribution to sex hormone production becomes particularly important after menopause in women, when the ovaries cease to be the primary source of estrogen.

The Pancreas: Regulating Blood Sugar and Digestion

The pancreas is a unique organ that serves both endocrine and exocrine functions. As part of the endocrine system, it plays a crucial role in regulating blood sugar levels and energy metabolism. The endocrine portion of the pancreas consists of clusters of cells called islets of Langerhans, which produce and secrete several important hormones.

How does the pancreas control blood sugar levels? The two primary hormones involved in blood sugar regulation are insulin and glucagon. These hormones work in opposition to maintain blood glucose within a narrow, healthy range:

• Insulin, produced by beta cells, lowers blood sugar by promoting glucose uptake by cells and storage as glycogen.
• Glucagon, produced by alpha cells, raises blood sugar by stimulating the breakdown of glycogen and the production of glucose by the liver.

What happens when insulin production or function is impaired? When the body cannot produce sufficient insulin or becomes resistant to its effects, it can lead to diabetes mellitus. This chronic condition affects millions of people worldwide and can have serious health consequences if left unmanaged.

Other Important Pancreatic Hormones

• Somatostatin: Inhibits the release of both insulin and glucagon
• Pancreatic polypeptide: Regulates pancreatic secretion and gastrointestinal motility
• Ghrelin: Stimulates appetite and plays a role in energy balance

In addition to its endocrine functions, the pancreas also serves as an exocrine gland, producing digestive enzymes that are released into the small intestine. These enzymes are essential for breaking down proteins, fats, and carbohydrates in the food we eat.

Reproductive Hormones: Orchestrating Sexual Development and Fertility

The reproductive system is intricately linked to the endocrine system, with hormones playing a crucial role in sexual development, fertility, and reproductive function. The primary reproductive glands – the ovaries in females and the testes in males – produce sex hormones that regulate various aspects of reproduction and sexual characteristics.

How do reproductive hormones influence sexual development? During puberty, the hypothalamus begins to secrete gonadotropin-releasing hormone (GnRH), which stimulates the pituitary gland to produce follicle-stimulating hormone (FSH) and luteinizing hormone (LH). These hormones, in turn, act on the ovaries or testes to promote the production of sex hormones and the development of secondary sexual characteristics.

Key Female Reproductive Hormones

• Estrogen: Promotes development of female secondary sexual characteristics and regulates the menstrual cycle
• Progesterone: Prepares the uterus for pregnancy and maintains pregnancy
• Inhibin: Regulates FSH production

Key Male Reproductive Hormones

• Testosterone: Promotes development of male secondary sexual characteristics and sperm production
• Inhibin: Regulates FSH production
• Anti-Müllerian hormone (AMH): Important in male fetal development

What role do reproductive hormones play in fertility? In females, the complex interplay of hormones regulates the menstrual cycle, ovulation, and pregnancy. The cyclic release of FSH and LH stimulates follicle development and ovulation, while estrogen and progesterone prepare the uterus for potential pregnancy.

In males, testosterone is essential for sperm production and maintaining sexual function. FSH and LH work together to stimulate testosterone production and spermatogenesis in the testes.

Reproductive hormones also influence other aspects of health, including bone density, muscle mass, and mood. As individuals age, changes in reproductive hormone levels can lead to significant physiological changes, such as menopause in women and andropause in men.

Hormone Imbalances: Causes, Symptoms, and Treatment Options

Hormone imbalances occur when there is too much or too little of a hormone in the bloodstream. Given the wide-ranging effects of hormones on the body, even small imbalances can lead to significant health issues. Understanding the causes, symptoms, and treatment options for hormone imbalances is crucial for maintaining overall health and well-being.

What are common causes of hormone imbalances? Hormone levels can be affected by various factors, including:

• Endocrine gland dysfunction
• Certain medications (e.g., steroids, opioids)
• Stress
• Diet and nutrition
• Environmental toxins
• Aging
• Genetic factors

How do hormone imbalances manifest in the body? The symptoms of hormone imbalances can vary widely depending on which hormones are affected. Some common signs and symptoms include:

• Unexplained weight gain or loss
• Fatigue
• Mood swings or depression
• Changes in heart rate or blood pressure
• Difficulty sleeping
• Changes in appetite
• Decreased libido
• Infertility
• Muscle weakness or joint pain

What treatment options are available for hormone imbalances? The treatment of hormone imbalances depends on the underlying cause and the specific hormones involved. Some common approaches include:

• Hormone replacement therapy
• Lifestyle modifications (diet, exercise, stress management)
• Medications to address specific symptoms
• Surgery (in cases of tumors or other structural issues)

It’s important to work closely with an endocrinologist or hormone specialist to diagnose and treat hormone imbalances properly. These medical professionals can conduct thorough evaluations, including blood tests and imaging studies, to determine the root cause of hormonal issues and develop appropriate treatment plans.

In conclusion, the endocrine system plays a vital role in maintaining overall health and well-being through the precise regulation of hormone levels. Understanding the functions of various endocrine glands and the hormones they produce is essential for recognizing potential imbalances and seeking appropriate medical care. By working with healthcare professionals and adopting healthy lifestyle habits, individuals can support optimal endocrine function and enjoy better overall health.

Hormones and Endocrine Function | Endocrine Society

Hormones and Endocrine Function | Endocrine Society

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Patient Resources

January 24, 2022

Hormones are are the body’s chemical messengers, sending signals into the bloodstream and tissues. Hormones work slowly, over time, and affect many different processes, including growth and development, metabolism – how your body gets energy from the foods you eat- sexual function, reproduction, and mood. When glands do not produce the right amount of hormones, diseases develop that can affect many aspects of life. 

Some factors that affect endocrine organs include puberty, aging, pregnancy, the environment, genetics and certain diseases and medications, including naturopathic medicine, herbal supplements, and prescription medicines such as opioids or steroids. Hormones are vital to your health and well-being. 

Hormone stability can be a delicate balancing act, which is why you want to work with a hormone specialist.  If you suspect hormone or endocrine-related problems get help from an endocrinologist near you.

Endocrine Library >>

• Adrenal gland secretes steroid hormones such as cortisol and aldosterone. It also makes precursors that can be converted to sex steroids such as androgen, estrogen. Learn more about adrenal disorders that can be caused by too much or too little of a particular hormone.

  Adrenal Hormones

• Found deep inside the brain, the hypothalamus produces releasing and inhibiting hormones and controls the “master gland”— the pituitary. Together, the hypothalamus and pituitary tell the other endocrine glands in your body to make the hormones that affect and protect every aspect of your health.

  Brain Hormones

• Several organs play a major role in helping the endocrine system to work well. Although these organs are not glands themselves, they do produce, store, and send out hormones that help the body to function properly and maintain a healthy balance.

  Endocrine-related Organs and Hormones

• Pancreas plays a crucial role in converting food into energy for cells and digestion. Learn what happens when too much or too little of the hormones glucagon and insulin affect the endocrine system.

  Pancreas Hormones

• Reproductive hormones play a big role in sexual development, weight, energy and fertility. Puberty, menstruation, sperm development and even menopause Learn more about the common hormones and disorders that impact both women and men.

  Reproductive Hormones

• Thyroid gland uses iodine from food to make two thyroid hormones that regulate metabolism, whereas the parathyroid glands produces hormones that control calcium. Learn how too much or too little can affect endocrine function.

  Thyroid and Parathyroid Hormones

• This resource will help you decode the most important hormones and explain how changes in hormone levels can affect your body and your well-being.

  Download the Essential Guide to Hormones

• Descifraremos las hormonas más importantes del organismo humano y explicaremos de qué manera los cambios en los niveles hormonales pueden afectar su organismo y su bienestar.

  Descargar Guia Esencial De Sus Hormonas

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January 24, 2022

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The Function of the Endocrine System

The Function of the Endocrine System – Glands & Hormones |

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The endocrine system is a specialised system that supports the body in its functionality. It can be compared to an orchestra in the sense that every musician – in this case, every gland – has its function. All musicians work together when playing or creating music. Similarly, all glands work together, monitored by the hypothalamus in the regulation of body…

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The Function of the Endocrine System – Glands and hormones

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The endocrine system is a specialised system that supports the body in its functionality. It can be compared to an orchestra in the sense that every musician – in this case, every gland – has its function. All musicians work together when playing or creating music. Similarly, all glands work together, monitored by the hypothalamus in the regulation of body functions. In short, the function of the endocrine system is that it is a network of organs that supports the regulation of the body’s functions through chemical messengers, known as hormones.

• We are going to delve into the world of the function of the endocrine system glands and hormones in psychology.
• First, we will explore the endocrine system’s organs and functions.
• We will provide a list of endocrine glands and their hormones to illustrate our discussion.
• Following this, we will also provide a glands hormones and their functions chart.
• Finally, we will discuss the various endocrine system diseases and how they affect the body.

Fig. 1 – The endocrine system has different functions.

The Function of the Endocrine System: Glands and Hormones in Psychology

The endocrine system is responsible for the production and transmission of information in the body via messenger substances called hormones. Hormones are produced in specialised organs called glands as well as in endocrine cells located in various organs throughout the body.

The endocrine system is a collection of glands across the body that secrete hormones.

The endocrine system works together with the nervous system to secrete hormones.

Hormones are chemical molecules that pass on information in the body through the bloodstream, with widespread effects.

Their main function is to control and regulate biological processes and rhythms as well as developmental processes. They can work locally or use the bloodstream to travel throughout the whole body to their effector organs.

Once released into the bloodstream, hormones keep on circulating in the body until broken down by the liver and kidneys.

Endocrine System Organs and Functions

The endocrine system transports specialised hormones to the different body parts of the blood system. The different hormones are produced by glands. The endocrine system is composed of several glands, such as the Pituitary gland, the Thyroid gland, the Pineal gland and the Gonads.

Fig. 2 – The endocrine system is comprised of different glands and hormones.

Among all components of the Endocrin system, there is an organ of special relevance, the hypothalamus.

• The hypothalamus can be considered the control centre of the endocrine system.

The hypothalamus controls the release of hormones from the pituitary gland, the master gland. In this way, the hypothalamus and the pituitary gland are connected.

The hypothalamus is the control centre, and the pituitary gland receives orders from the hypothalamus and enacts them across the endocrine system, acting as the master gland.

Types of Glands

Glands are specialised organs that create hormones or other substances, such as tears, sweat, milk, seminal fluid or saliva. Glands can be split into two categories:

Hormones are produced in the endocrine glands in the human body. The hormones they produce have one or many effectors, meaning the organs that they affect. The endocrine glands include the:

Some hormones’ only function is to stimulate the release of other glands. These are called indirect action hormones. The glands cued to produce hormones by indirect action hormones are called target glands. Other hormones affect organs directly; these are called direct action hormones or effector hormones.

List of Endocrine Glands and their Hormones

As we discussed above, there are different types of endocrine glands. Consider the following list of endocrine glands and their hormones:

• The thyroid gland contains thyroid hormones (thyroxine and triiodothyronine) which influence growth and metabolism.

• The pineal gland releases melatonin and is involved in sleep.

• The pancreas is in charge of the production and release of insulin, which influences blood sugar levels and stimulates the metabolism of glucose, protein and fat.

• The testicles release androgens such as testosterone, which is involved in the development of male sexual characteristics.

• The ovaries release estrogen, which supports reproductive development in females and female sexual characteristics.

• The adrenal glands secrete two types of hormones: epinephrine – which is involved in oxygen intake, blood flow and heart rates – and norepinephrine – which is involved in blood pressure, blood vessels, and glucose release.

You don’t have to learn all the different hormones for your exam, it’s enough to have a rough idea of how they work and to be able to explain two or three.

The Pituitary Gland

One of the most important glands is located in the brain; the pituitary gland, also called the master gland.

The pituitary gland controls the production and secretion of many other hormones.

Part of it, the posterior pituitary gland, is an extension of the part of the brain called the hypothalamus. It is not glandular.

The other part, the anterior pituitary gland, is glandular and connects to the posterior pituitary and contains cells that produce many hormones. These so-called releasing hormones in turn tell the target glands in the body to produce local or specialised hormones that affect another set of organs in the body.

It’s a bit like if you ordered a new games console for a friend. You (the hypothalamus) tell provider through one website what you want (pituitary). They coordinate with sellers and warehouses in different countries (target glands).

These sellers pack and send packages to your friend’s delivery address (effector organs). Now they have no more excuses and can get to playing (effect).

Glands, Hormones and their Functions Chart

Here there is a table of the different glands, and the hormones they release, together with the hormones’ functions.

Gland name	Hormone released	Function
Pituitary Gland	Anterior PG – Adrenocorticotropic hormone (ACTH)	Involved in the production of cortisol and stimulation of the adrenal glands.
	Posterior PG – Oxytocin and Vasopressin	Involved in the contraction of the uterus at birth and water conservation and blood vessels, respectively
Adrenal Gland	Adrenal Medulla – Adrenaline and Noradrenaline	Involves in the fight or flight response. Supports oxygen intake, blood flow, increased heart rate and blood pressure maintenance.
	Adrenal Cortex – Cortisol
Ovaries	Estrogen	Involved in the development of sexual characteristics in females.
	Progesterone	Involved in the preparation of the uterus and the breasts for reproductory reasons.
Testicles	Testosterone	Involved in the development of sexual characteristics in males.
Thyroid Gland	Thyroxine	Supports the body’s metabolism and also affects growth and maturation.
Thymus Gland	Thymulin	Anti-inflammatory effects, involved in T-cells.
Pineal Gland	Melatonin	Melatonin release at night supports sleep.

Endocrine System Diseases

There are certain diseases associated with failures of the endocrine system. These failures can take place due to two reasons:

1. A change in the level of hormones secreted by a gland.
2. A change in the gland’s receptors sensitivity leads to the gland not responding correctly to stimulation.

Hormone imbalance can influence several conditions, such as mood or fertility. Among the diseases associated with the endocrine system are diabetes, hypothyroidism and hypogonadism. Let’s take a look at these diseases.

Diabetes

Diabetes is a metabolic condition in which glucose concentration in the blood is high. The disease is caused by issues with insulin, which is produced in the pancreas.

There are two ways in which diabetes can occur. One is that the pancreas does not produce the necessary amount of insulin, a genetic condition, and the second is that the insulin receptors across the body present insensitivity to the hormone and less insulin is produced, a result of lifestyle choices.

Hypothyroidism

Hypothyroidism is a condition in which the supply of thyroid hormones is low. It can be preset due to two reasons.

• On the one hand, the thyroid can be producing low levels of thyroid hormones.
• While on the other hand, it could be that the thyroid-stimulating hormone is failing to achieve its function.

The effect that hypothyroidism is manifested in symptoms of fatigue, tiredness, constipation or muscle weakness

Hypogonadism

Hypogonadism refers to a spectrum disorder characterised by insufficient sex hormones. Equally to the previous two disorders, hypogonadism can arise due to a low level of the production of the hormones, or due to an insensitivity of the organs to the hormone themselves. The effects that the disorder has, vary depending on the time at which hypogonadism is developed.

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The Function of the Endocrine System – Glands and hormones – Key takeaways

• The endocrine system is responsible for transferring information via messenger molecules called hormones through the bloodstream in the body, similar to neurotransmitters.
• Hormones have widespread effects across the body, and binding to any type of receptors that match up with the hormone.
• The endocrine system has long-term and long-lasting effects on the regulation of biological processes.
• Endocrine glands are organs specialised in producing hormones. Examples of endocrine glands include the thyroid, thymus, pituitary gland, pineal gland, pancreas, testicles, ovaries and adrenal glands.
• There are certain diseases associated with the endocrine system malfunctioning, such as diabetes, hypothyroidism and hypogonadism.

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References

1. Fig. 2: Endocrine system diagram by Spielman, R. M., Jenkins, W. J., & Lovett, M. D. (2020). 3.5 The Endocrine System. In Psychology 2e. OpenStax. https://openstax.org/books/psychology-2e/pages/3-5-the-endocrine-system.
2. This work is licensed under a Creative Commons Attribution 4.0 International License.

Frequently Asked Questions about The Function of the Endocrine System – Glands and hormones

The endocrine system is the system responsible for the production and transmission of information in the body via messenger substances called hormones. These are produced in specialised organs called glands as well as in endocrine cells located in various organs throughout the body. Hormones are chemical molecules that pass on information in the body. 

Pineal gland: melatonin.
Pituitary gland: Adrenocortical trophic hormone & Oxytocin.

Thyroid gland: Thyroxine.

Adrenal gland: Adrenaline, noradrenaline.

Glands are specialised organs whose function is to produce hormones.  

Some of the endocrine system’s glands and hormones are the following:

• The thyroid gland releases thyroxine.

• The pineal gland releases melatonin.

• The pancreas releases insulin.

• The testicles release testosterone.

• The ovaries release estrogen and progesterone.

• The adrenal glands secrete epinephrine and norepinephrine. 

Diabetes, hypothyroidism and hypogonadism.

Final The Function of the Endocrine System – Glands and hormones Quiz

The Function of the Endocrine System – Glands and hormones Quiz – Teste dein Wissen

Question

What’s the main function of the endocrine system?

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Answer

The main function of the endocrine system is the transmission of information through hormones throughout the body.

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Question

What are three diseases related to the endocrine system?

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Answer

Diabetes, hypothyroidism and hypogonadism.

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Question

The main function of testosterone is to _______.

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Answer

Develop sexual characteristics in males.

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Question

True or False: The pituitary gland is the master gland.

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Answer

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Question

Does the thyroid gland take part in metabolism?

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Answer

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Question

True or False: Hormones have one function in the body.

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Answer

False.

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Question

Which of these is not a hormone function?

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Answer

Urine-intake.

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Question

What are glands?

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Answer

Glands are specialised organs that create hormones or other substances such as tears, sweat, milk, seminal fluid or saliva.

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Question

If a gland produces a substance that is released via ducts, it is an ________ gland.

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Answer

Exocrine.

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Question

Which are the major endocrine glands ?

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Answer

The pituitary gland, the pineal gland, the thyroid gland, the adrenal gland, the pancreas, the ovary and the testicles.

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Question

What’s an effector?

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Answer

An effector is an organ that a substance works on, producing an effect.

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Question

True or False: Hormones have widespread effects across the body.

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Answer

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True or False: Indirect action hormones is a hormone that facilitates direct action hormones

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Answer

False.

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Question

The ___ pituitary gland is part of the brain.  

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Answer

Posterior.

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Question

Which are the hormones involved in the fight or flight response?

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Answer

Adrenaline, noradrenaline and cortisol.

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Question

What is the main function of adrenaline?

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Answer

To support oxygen intake, blood flow, increased heart rate and blood pressure maintenance.

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Question

Which organs of the body break down hormones?

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Answer

The liver and kidneys break down hormones in the bloodstream.

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Functions of the endocrine glands in the human body.

Tests for hormones and their interpretation.

The human endocrine system consists of organs called endocrine glands, which regulate the functioning of the whole organism by releasing biologically active substances – hormones – into the circulatory system. These substances perform paramount functions in the body: they help maintain homeostasis, control growth and development, participate in metabolic processes, are responsible for responding to changes in environmental conditions, and regulate the reproductive system.

Endocrine glands include:

Thyroid. Produces hormones – thyroxine (T4), triiodothyronine (T3), calcitonin. These hormones are involved in metabolism, increasing its intensity, regulate growth processes in the body, increase the level of consumption of vital oxygen by organs and tissues.

Parathyroid glands. They produce parathyroid hormone that regulates the level of calcium in the body, which is necessary for the normal functioning of the motor apparatus and nervous system.

Thymus (thymus). This organ occupies a central place in the human immune system, not without reason the word “thymus” is translated from ancient Greek as “life force”. The thymus produces T-lymphocytes – immune cells that provide antiviral and antitumor protection of the body. It secretes a number of hormones into the blood: thymalin, thymosin, IGF-1, thymopoietin, which are responsible for the functional activity of the immune system.

Adrenals. They produce the so-called stress hormone – adrenaline, which is involved in the body’s response to external stressful situations. When a large amount of adrenaline is released into the blood, breathing quickens, the heart rate increases, blood vessels constrict, and the pupils dilate.

Pancreas. Is the main source of enzymes for the digestion of fats, proteins and carbohydrates. It produces the hormones insulin, which lowers the level of glucose in the blood, and glucagon, on the contrary, increases it.

Gonads. In women, the ovaries; in men, the testes. The hormones produced by these glands are responsible for reproductive function.

Pituitary and hypothalamus. Form the hypothalamic-pituitary system. The pituitary gland produces hormones that control almost the entire endocrine system. Among them, the most important is the growth hormone – somatotropin, which affects the growth of bones, cartilage and muscles.

Epiphysis (pineal body, or pineal gland). The organ performs important functions: it slows down growth hormones, inhibits the development of tumors, and affects sexual development. It produces antidiuretic hormone (ADH), which controls the water balance of the body, oxytocin, which is responsible for muscle contraction, and melatonin, a hormone that controls the sequence of sleep phases.

Based on the foregoing, we can follow the conclusion that the importance of the endocrine system cannot be overestimated – its activity extends to all organs of the body and all processes occurring in it. Therefore, all deviations from the norm in the operation of this system require immediate medical intervention.

Symptoms of hormonal imbalance

There are a lot of symptoms of malfunctioning of the endocrine glands, among them are:

• Irregular or absent menstruation in women;
• Miscarriage or infertility;
• Loss of sexual desire;
• Weight gain;
• Eruptions on the body, acne;
• Deterioration of hair and nails;
• Sleep disturbances, lethargy, increased fatigue;
• Emotional instability: tearfulness, irascibility, nervousness;
• The development of osteoporosis is a disease that leads to brittle bones.

It is worth noting that none of the above symptoms is a direct confirmation of the presence of a hormonal imbalance, but only a possible consequence. To make an accurate diagnosis, it is necessary to undergo a complete examination by an endocrinologist, which includes the method of functional diagnostics (ultrasound, MRI), as well as laboratory blood tests, which will be discussed below.

How is blood tested for hormones?

A blood test for hormones is the most indicative and informative method for detecting any pathologies in the work of the endocrine glands. However, it is important to consider that many factors influence the hormonal background: the time of day, the menstrual cycle in women, and medication. For this reason, the preparation for taking tests for a hormonal study must be taken with all seriousness. If this is neglected, then the result of the analysis may be incorrect and, at best, it will have to be retaken, and at worst, an incorrect diagnosis may be made on its basis and the wrong treatment may be prescribed, which can lead to irreparable consequences.

To prepare for donating blood for hormones, the following general rules must be observed:

• On the eve of the test, you should give up physical activity, try to avoid stressful situations, stop any physiotherapy procedures, exclude oral contraceptives, alcohol, fatty foods and products containing iodine. It is also recommended to postpone the ECG, ultrasound, x-ray examination for a while after the test.
• An important point is taking medications – it is necessary to notify the doctor who ordered the hormonal blood test about the fact of taking medications. He will decide whether to cancel or continue taking medications at the time of the test.
• An analysis for a hormonal study is given strictly on an empty stomach. Therefore, it is recommended to stop eating 12 hours before blood sampling.
• In the morning, before the test, it is forbidden to chew gum, drink tea and smoke.
• Just before donating blood, rest for 15-10 minutes.
• Women need to take into account their menstrual cycle, because. it is possible to examine the blood for some hormones only in certain periods of this cycle.
• To track the dynamics of the levels of certain hormones, a second analysis is required. It is rented at approximately the same time as the previous one, in compliance with all the above rules.

Blood sampling for analysis is carried out in the first half of the day in the morning. The biomaterial is taken from the cubital vein.

Explanation of tests

Thyroid hormones

Triiodothyronine , or T3 – gives a general assessment of the work of the thyroid gland. This hormone is determined both in free form (norm: from 2.6 to 5.7 pmol/l.), And in the serum state, (general form; norm: from 1.3 to 2.7 nmol/l). An increase in the indicator indicates the use of narcotic substances: methadone, heroin, amphetamine, HIV infection, renal failure, hyperthyroidism. The decrease was established with the use of androgens, danazol, dexamethasone, propranolol.

Thyroxine , or T4 – regulates energy metabolism in the body. Norm: 10.8 – 22.0 pmol / l. A low level is observed with hyperthyroidism, hemolysis. Elevated levels – when taking oral contraceptives, methodone, heroin, estrogen.

Thyroglobulin , or Tg – is prescribed for suspected malignant neoplasms. Norm: < 55 ng / ml.

Antibodies to thyroglobulin – are prescribed for suspected autoimmune thyroid diseases. Norm: 0 – 18 U / ml.

Microsomal antibodies are the most accurate indicator of the presence of autoimmune diseases. A deviation from the norm < 5.6 U / ml is proof of the aggression of the immune system to its own body.

Thyroxine-binding globulin , or TSH, is responsible for the transport of the hormones T3 and T4. Norm: from 16.8 to 22.5 mcg / ml. An increased indicator may indicate pregnancy, a lower one – with cirrhosis of the liver.

Adrenal hormones

Cortisol – regulates carbohydrate metabolism. Norm: from 230 to 750 nm / l. A low rate may be the result of chronic adrenal insufficiency, and a high one may indicate oncology or adenoma.

Aldosterone – responsible for the water-salt balance. Norms: in a horizontal position 17. 6-230.2 pg / ml; in an upright position 25.2-392 pg / ml. Elevated levels of the hormone in the blood usually indicate an adrenal tumor.

Norepinephrine and epinephrine – normalize heart rate, blood pressure, form glucose levels. Norms: from 1.92 to 2.46 nm / l for adrenaline, from 0.62 to 3.23 nm / l for norepinephrine. An increase in indicators indicates kidney disease, Itsenko-Cushing’s syndrome, emotional and physical workload of the body, a decrease indicates pathology of the hypothalamus.

Sex hormones

Estradiol – is responsible for the production of germ cells and the proper development of pregnancy. The norm in the first phase of the menstrual cycle (follicular phase) is from 200 to 285 pm/l, the norm in the corpus luteum phase (luteal phase) is from 440 to 575 pi/l, during menopause from 50 to 133 pm/l. A lower indicator may indicate a tumor in the ovaries, an increased indicator – with their insufficient functioning.

Testosterone is the main male hormone. Responsible for the formation of secondary sexual characteristics, stimulates the growth of muscle mass and bones. Norms: for men – 2 -10 ng / ml, for women – 0.2 – 1 ng / l.

Progesterone – ensures the proper development of the genital organs in women. The norm in the first phase of the menstrual cycle (follicular phase) is from 1 to 2.2 nm / l, the norm in the corpus luteum phase (luteal phase) is from 23 to 30 nm / l, during menopause from 1 to 1.8 nm / l . An increase in the indicator is observed with tumors of the adrenal cortex, a decrease – with ovarian sclerosis.

Pituitary hormones

Thyroid stimulating hormone , or TSH, stimulates the production of the main thyroid hormones, so deviations from the reference values ​​​​indicate thyroid dysfunction. Norm: 0.4-4.0 honey / l.

Somatotropic hormone , or STH – a hormone of the anterior pituitary gland, is responsible for stimulating the mouth of bones, muscle mass and other organs of the human body. Norm: < 10.0 ng / ml. Exceeding the value of the established norm indicates gigantism, acromegaly.

Adrenocorticotropic hormone , or ACTH – stimulates the synthesis of hormones in the adrenal cortex. Norm: < 46 pg / ml. Deviations from the norm are observed in Itsenko-Cushing's syndrome, Addison's disease, as well as in other disorders of the adrenal glands.

Prolactin is a hormone responsible for the growth of the mammary glands in women and the functioning of the prostate in men. The norm for the stronger sex is 100 – 265 mcg / l, for the fair sex – from 130 to 540 skg / l during the childbearing period.

Follicle-stimulating hormone , FSH – stimulates the growth of follicles in women, is responsible for the functioning of the seminiferous tubules in men. The norm in women: in the first phase of the menstrual cycle (follicular phase) from 1.37 – 9.90 IU / l, in the corpus luteum phase (luteal phase) from 1. 09 – 9.20 IU / ml, during menopause from 29, 5 to 55 mU / l, with ovulation from 2.7 to 6.7 mU / ml. The norm for men: 0.95 – 11.95 mU / ml.

Luteinizing hormone , or LH – stimulates the production of testosterone in men, progesterone in women. Normal values ​​for men: from 1.14 to 8.75 mU / ml. Norm for women: in the follicular phase from 1.68 to 15.00 mU / ml, in the ovulatory phase from 21.90 – 56.60 mU / ml, in the luteal phase: 0.61 – 16.30 mU / ml, in postmenopausal women from 14.20 – 52.30 mU / ml. Deviations from normal values ​​in both sexes indicate dysfunction of the gonads.

Endocrine system. Humoral regulation – what is it, definition and answer

All glands of the body are usually divided into glands:

• Internal secretion = endocrine (releasing hormone into the blood): thyroid gland, pituitary gland, adrenal glands, pineal gland, thymus.

• External (excrete into the body cavity or beyond): sweat, sebaceous, salivary, mammary glands.

• Mixed secretion (hormone + secretion into the blood + into the body cavity or beyond): pancreas, gonads.

All endocrine glands secrete hormones.

Hormones are biologically active substances that are produced in specialized cells of the endocrine glands, enter the blood and have a regulatory effect on metabolism and physiological functions.

Pituitary gland (midbrain)

Pituitary gland is the most important gland that regulates many functions of the body, some of its hormones control the activity of other endocrine glands, for example, pituitary hormone thyrotropin stimulates the production and activation of thyroxine, a thyroid hormone glands.

Other hormones also have a tremendous effect on the body, for example, somatotropin (growth hormone) regulates the growth of the body at a young age, with a lack of it, dwarfism will develop, and with an excess, gigantism.

Epiphysis (midbrain)

This endocrine gland plays the role of a “biological clock”. Receiving information about the time of day from the visual analyzer, the pineal gland controls the production of melatonin . This hormone is responsible for the regulation of circadian rhythms, that is, for the desire to sleep and stay awake.

Pineal hormones also affect the functions of the pituitary gland (hormone serotonin ), thyroid gland, adrenal glands, control puberty and inhibit the function of the gonads in childhood.

Thymus

In the chest behind the sternum is located the thymus, or the thymus. It consists of two lobes resembling the horns of a fork. Its value changes with age – in childhood, the thymus is much larger than in adulthood.

Thymus is the central organ of the immune system.

Immune cells are formed and trained in it, harmful agents are “remembered”, the formation of immunity depends on it.

Thyroid and parathyroid glands

Thyroid gland is the largest endocrine gland of internal secretion. It consists of two lobes that hug the upper part of the trachea like a tie. On the back surface are 4 parathyroid (parathyroid) glands.

Thyroxine – the most important thyroid hormone, it affects the whole body and regulates metabolism. Iodine is required for its synthesis.

With hypofunction (deficiency) of thyroxin, adults develop myxedema , which is expressed in swelling, decreased metabolism and excitability of the nervous system, and obesity. Children will develop dwarfism with a violation of body proportions and cretinism.

With hyperfunction (excess) of thyroxin, increased excitability of the nervous system, increased metabolism, weight loss, the appearance of goiter – an increase in the size of the thyroid gland.

Another thyroid hormone calcitonin is responsible for controlling the amount of calcium in the blood. Together with parathyroid hormones, it maintains the level of calcium in the blood within the normal range.

Adrenal glands

Adrenal glands are paired glands that are located at the tops of the kidneys. They consist of inner (brain) and outer (cortical) layers.

The hormone of the inner layer adrenaline accelerates the work of the heart, constricts blood vessels, slows down digestion, increases the amount of glucose in the blood.

Hormones of the outer layer corticoids regulate the metabolism of mineral and organic substances, the release of sex hormones, the activity of allergic and inflammatory reactions.

Pancreas

Pancreas – large gland mixed secretion. It secretes digestive enzymes into the duodenal cavity, and the hormone insulin into the blood (endocrine function).

Insulin regulates blood glucose, glycogen synthesis from excess glucose, fat deposition.

With hypofunction , a disease such as diabetes mellitus develops, which is accompanied by an increase in blood sugar, the appearance of sugar in the urine, increased pressure and blood viscosity, and many other side effects.

In case of hyperfunction of the pancreas, a lack of glucose is formed in the blood, the brain may lack nutrition and a person may fall into a coma.

Sex glands

Sex glands, or gonads – testes (testicles) in men and ovaries in women are among the glands with mixed secretion.

Gonads are referred to glands of mixed secretion .

Sex hormones promote embryonic differentiation, the subsequent development of the genital organs and the appearance of secondary sexual characteristics, determine puberty and human behavior.

Male sex hormones (androgens)

All sex hormones are synthesized from one precursor – cholesterol. The most important of the androgens is testosterone.

Female sex hormones

These hormones are produced in the female sex glands – the ovaries, during pregnancy – in the placenta. Men also produce female sex hormones, just in smaller quantities. It occurs in the cells of the testicles.

In the ovarian follicles, estrogens are synthesized ( stimulate the development of primary and secondary female sexual characteristics, the development and growth of the mammary glands, affect the development of the bone skeleton, the emotional and mental state of women; during pregnancy, estrogens promote the growth of uterine muscle tissue, effective uterine – placental circulation, together with progesterone and prolactin – the development of the mammary glands).

The corpus luteum of the ovary produces progesterone (prepares the uterus for the attachment of a fertilized egg and ensures the normal course of pregnancy; participates in the regulation of the menstrual cycle).