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Describe the role of the endocrine system in the body: What is the Endocrine System?

Endocrine System (for Teens) – Nemours Kidshealth

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

What Does the Endocrine System Do?

  • Endocrine glands release
    hormonesinto 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 (pronounced: 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 (pronounced: 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 (pronounced: pro-LAK-tin), which activates milk production in women who are breastfeeding
  • thyrotropin (pronounced: thy-ruh-TRO-pin), which stimulates the thyroid gland to make thyroid hormones
  • corticotropin (pronounced: kor-tih-ko-TRO-pin), which stimulates the adrenal gland to make certain hormones
  • antidiuretic (pronounced: an-ty-dy-uh-REH-tik) hormone, which helps control body water balance through its effect on the kidneys
  • oxytocin (pronounced: ahk-see-TOE-sin), which triggers the contractions of the uterus that happen during labor

The pituitary also secretes endorphins (pronounced: 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

ovulationand the menstrual cycle in women.

Thyroid: The thyroid (pronounced: 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 (pronounced: thy-RAHK-sin) and triiodothyronine (pronounced: 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 (pronounced: par-uh-THY-roydz). They release parathyroid hormone, which controls the level of calcium in the blood with the help of calcitonin (pronounced: kal-suh-TOE-nin), which the thyroid makes.

Adrenal Glands: These two triangular adrenal (pronounced: 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 (pronounced: 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 (pronounced: muh-DUH-luh). It makes catecholamines (pronounced: kah-tuh-KO-luh-meenz), such as epinephrine (pronounced: eh-puh-NEH-frun). Also called adrenaline, epinephrine increases blood pressure and heart rate when the body is under stress.

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

Reproductive Glands: The gonads are the main source of sex hormones. Most people don’t realize it, but both guys and girls have gonads. In guys the male gonads, or testes (pronounced: TES-teez), are in the scrotum. They secrete hormones called androgens (pronounced: AN-druh-junz), the most important of which is

testosterone(pronounced: tess-TOSS-tuh-rone). These hormones tell a guy’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 guy’s body when it’s time to make sperm in the testes.

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

estrogen(pronounced: ESS-truh-jen) and
progesterone(pronounced: 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 (pronounced: PAN-kree-us) makes insulin (pronounced: IN-suh-lin) and glucagon (pronounced: 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.

How Can I Help Keep My Endocrine System Healthy?

To help keep your 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 you:

  • drink a lot of water but are still thirsty
  • have to pee often
  • have frequent belly pain or nausea
  • are very tired or weak
  • are gaining or losing a lot of weight
  • have tremors or sweat a lot
  • are constipated
  • are not growing or developing as expected

Hormonal (endocrine) system – Better Health Channel

Endocrine glands make chemicals called hormones and pass them straight into the bloodstream. Hormones can be thought of as chemical messages.

From the blood stream, the hormones communicate with the body by heading towards their target cell to bring about a particular change or effect to that cell. The hormone can also create changes in the cells of surrounding tissues (paracrine effect). The endocrine system works with the nervous system and the immune system to help the body cope with different events and stresses.

This branch of medicine – relating to the study of the endocrine system – is called endocrinology and is practiced by endocrinologists. The field is rapidly expanding due to understanding of the cellular pathways that hormones stimulate and the discovery of new hormones and their actions.

Exocrine glands

An exocrine gland, unlike an endocrine gland, is a gland that secretes substances (electrolytes, proteins or enzymes) straight to a target site via ducts or tube. Some examples include:

  • Salivary glands
  • Sweat glands
  • Sebaceous glands
  • The pancreas.

The pancreas is both an endocrine and exocrine organ. It releases certain enzymes to aid in digestion delivered to the gut via the pancreatic duct. The endocrine pancreas also releases hormones such as insulin and glucagon, which are hormones predominantly related to glucose metabolism, into the blood stream.

Functions of the endocrine system

Some of the roles of the endocrine system include:

  • Growth
  • Repair
  • Sexual reproduction
  • Digestion
  • Homeostasis (constant internal balance).

How hormones work

A hormone will only act on a part of the body if it ‘fits’. A hormone can be thought of as a key, and its target site (such as an organ) has specially shaped locks on the cell walls. If the hormone fits the cell wall, then it will work.

The hormones can set off a cascade of other signaling pathways in the cell to cause an immediate effect (for instance, insulin signaling leads to a rapid uptake of glucose into muscle cells) or a more delayed effect (glucocorticoids bind to DNA elements in a cell to switch on the production of certain proteins, which takes a while to produce).

The endocrine system is a tightly regulated system that keeps the hormones and their effects at just the right level. One way this is achieved is through ‘feedback loops’. The release of hormones is regulated by other hormones, proteins or neuronal signals.

The released hormone then has its effect on other organs. This effect on the organ feeds back to the original signal to control any further hormone release. The pituitary gland is well known for its feedback loops.

Endocrine glands and organs

The main glands and organs of the endocrine system include:

  • Pituitary gland – is inside the brain. It oversees the other glands and keeps hormone levels in check. It can bring about a change in hormone production somewhere else in the system by releasing its own ‘stimulating’ hormones. The pituitary gland is also connected to the nervous system through part of the brain called the hypothalamus. The hormones released by the pituitary gland are gonadotropins (LH and FSH), growth hormone (GH), thyroid stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), prolactin, antidiuretic hormone and oxytocin.
  • Thyroid gland – sits in the neck at the front of the windpipe. It releases thyroid hormone (T4 and T3) which is required for metabolism and body homeostasis. It is controlled by TSH which is produced by the pituitary gland through a feed-back loop.
  • Parathyroid gland – there are usually four parathyroid glands which lie alongside the thyroid gland. The parathyroid gland is involved in calcium, phosphate and vitamin D regulation.
  • Adrenal glands – there are two adrenal glands which sit on top of each kidney. They make a number of different hormones. The outside part of the gland (adrenal cortex) makes cortisol, aldosterone and sex hormones. The centre of the adrenal gland (adrenal medulla) makes adrenaline. Adrenaline is an example of a hormone that is under the control of the nervous system.
  • Pancreas – an organ of digestion which is inside the abdomen. It makes insulin, which controls the amount of sugar in the bloodstream. It also makes other hormones such as glucagon and somatostatin.
  • Ovaries – are inside the female pelvis. They make female sex hormones like oestrogen.
  • Testes – they hang in the male scrotal sack. They make male sex hormones like testosterone.

Other lesser known endocrine organs include:

  • Adipose tissue (fat tissue) – is recognised to be metabolically important. It releases hormones such as leptin, which affect appetite, and is also a site of oestrogen production. Insulin also acts on adipose tissue.
  • Kidneys – produce erythropoietin (EPO) which stimulates red blood cell production, produce renin which is needed for blood pressure regulation and produce the active form of Vitamin D (1–25 dihydroxy vitamin D3)
  • Gut – an increasing number of hormones in the gut are being researched and being understood to effect metabolism and appetite. Included are glucagon-like peptide 1 (GLP–1), ghrelin which stimulates appetite, and somatostatin.

Problems of the endocrine system

Numerous problems can occur in the endocrine system. These can be considered as excessive or deficient hormone production. Endocrine organs are also prone to tumours (adenomas) which can over produce hormones. Some problems of the endocrine system include:

  • Diabetes – too much sugar in the blood caused by problems with insulin production. This includes type 1 diabetes (deficiency of insulin) and type 2 diabetes (initially excessive, then deficiency, of insulin).
  • Menstruation abnormalities – irregular menstruation or lack of menstruation. Some causes of this include polycystic ovarian syndrome (PCOS), pituitary adenoma or primary ovarian failure (POF).
  • Thyroid problems – when the gland is overactive (hyperthyroidism) or underactive (hypothyroidism). Thyroid nodules are common but thyroid cancers are rare.
  • Parathyroid problems – an enlargement or one of more of the parathyroid glands can lead to high calcium levels in the blood (hypercalcemia).
  • Pituitary adenomas – these are tumours of the pituitary gland that can make too much of a certain hormone or cause deficiencies of hormones. These tumours can be small (microadenomas) or large (macroadenomas).
  • Neuro-endocrine tumours – these are rare to tumours of certain endocrine glands (usually the adrenal gland, pancreas or small bowel). These can include too much adrenaline released by the adrenal gland (pheochromocytoma), or too much hormone 5–HIAA from a carcinoid tumour which causes diarrhoea and flushing.

Where to get help

  • Australian Pituitary Foundation Tel. 1300 331 807
  • Thyroid Australia Tel. (03) 9888 2588
  • Diabetes Australia Tel. 13 RISK (13 7475)
  • Unicorn Foundation (for neuro-endocrine disorders) Tel. 1300 CURE NETS (2873 6387)
  • Andrology Australia Tel. 1300 303 878
  • Australian Menopause Society Tel. (07) 4642 1603
  • Jean Hailes for Women’s Health Tel. 1800 JEAN HAILES (532 642)

Things to remember

  • Endocrine glands secrete hormones straight into the bloodstream.
  • Hormones help to control many body functions, such as growth, repair and reproduction.
  • The endocrine system involves many organ systems and hormones, many of which are still being investigated and understood.

Endocrine Function – Hormonal and Metabolic Disorders

Blocks the effects of insulin on muscle

Helps regulate salt and water balance by causing the kidneys to retain salt and water and excrete potassium

Has widespread effects throughout the body

Especially has anti-inflammatory action

Maintains blood sugar level, blood pressure, and muscle strength

Helps control salt and water balance

Dehydroepiandrosterone (DHEA)

Has effects on bone, mood, and the immune system

Epinephrine and norepinephrine

Stimulate the heart, lungs, blood vessels, and nervous system

Controls gallbladder contractions that cause bile to enter the intestine

Stimulates release of digestive enzymes from the pancreas

Controls growth hormone release from the pituitary gland

Causes sensation of hunger

Increases insulin release from the pancreas

Corticotropin-releasing hormone

Stimulates release of adrenocorticotropic hormone

Gonadotropin-releasing hormone

Stimulates release of luteinizing hormone and follicle-stimulating hormone

Growth hormone–releasing hormone

Stimulates release of growth hormone

Inhibits release of growth hormone, thyroid-stimulating hormone, and insulin

Thyrotropin-releasing hormone

Stimulates the release of thyroid-stimulating hormone and prolactin

Stimulates red blood cell production

Controls the development of female sex characteristics and the reproductive system

Prepares the lining of the uterus for implantation of a fertilized egg and readies the mammary glands to secrete milk

Raises the blood sugar level

Lowers the blood sugar level

Affects the processing (metabolism) of sugar, protein, and fat throughout the body

Controls bone formation and the excretion of calcium and phosphorus

Corticotropin (also called adrenocorticotropic hormone [ ACTH])

Controls the production and secretion of hormones by the adrenal glands

Controls growth and development

Promotes protein production

Luteinizing hormone and follicle-stimulating hormone

Control reproductive functions, including the production of sperm and semen in men and egg maturation and menstrual cycles in women

Control male and female sexual characteristics (including hair distribution, muscle formation, skin texture and thickness, voice, and perhaps even personality traits)

Causes muscles of the uterus to contract during childbirth and after delivery and stimulates contractions of milk ducts in the breast, which move milk to the nipple

Starts and maintains milk production in the ductal glands of the breast (mammary glands)

Thyroid-stimulating hormone

Stimulates the production and secretion of hormones by the thyroid gland

Vasopressin (antidiuretic hormone)

Causes kidneys to retain water and, along with aldosterone, helps control blood pressure

Stimulates ovaries to continue to release progesteroneduring early pregnancy

Estrogen and progesterone

Keep uterus receptive to fetus and placenta during pregnancy

Controls the development of male sex characteristics and the reproductive system

Tends to decrease blood calcium levels and helps regulate calcium balance

Regulate the rate at which the body functions (metabolic rate)

Structures & Functions of the Endocrine System – Video & Lesson Transcript

Control Glands

There are several glands located throughout the body, and all of them are important. However, there are two glands in the brain that are like the masterminds of the other organs. The hypothalamus is a lot like the operations manager in a factory that makes sure every aspect of the factory is functioning optimally. The hypothalamus is a small gland in the brain that assesses the body’s environment and releases hormones that control other glands. The hypothalamus essentially coordinates and dictates the activities of all other glands in order to keep the body functioning properly.

The other major gland in the brain is the pituitary gland. This is the gland that controls the rest of the endocrine system. This may start to seem like the body factory has two operations managers. The pituitary gland does control the rest of the endocrine system, but it does so under the direction of the hypothalamus. So the operations manager, or hypothalamus, tells the production manager, or pituitary gland, when production of the different hormones should start and stop. The pituitary gland is divided into the anterior and posterior pituitary glands.

Glands Controlled by the Pituitary Glands

Our first set of glands in the body are the ones controlled by the anterior pituitary gland. Let’s look at each of these now.

The thyroid gland is the gland located in the neck between the larynx and trachea. Hormones are secreted by the thyroid when the anterior pituitary gland, or production manager, sends the signal to start production. The thyroid hormones directly affect metabolism and indirectly affect blood calcium levels.

The adrenal glands are the triangle-shaped glands that sit on top of the kidneys. There are two sections of the adrenal glands: the adrenal cortex and adrenal medulla. Only the adrenal cortex responds to the anterior pituitary gland. The hormones released by the adrenal cortex control blood pressure, the immune system, and energy conversion. The hormones of the adrenal medulla are released in response to stress.

The last pair of glands that are under control of the pituitary gland are the gonads or sex glands, which are glands that secrete sex hormones. We’ll look at each of these separately, since they are different in males versus females.

Ladies first! The small, oval-shaped pair of female gonads are the ovaries, which secrete two different hormones that control the female reproductive cycle and the process of puberty.

The oval-shaped male gonads located in the scrotum are the testes. A hormone to control the development of male body characteristics is released by the testes when the production manager sends production signals to the testes.

Glands Not Controlled by the Pituitary Glands

Another gland that is located in the brain is the pineal gland, also sometimes called the third eye. It gets that nickname because it is activated based on signals from the optic nerve. So this gland isn’t really part of the factory that works together. The pineal gland is a gland shaped similar to a corn kernel and secretes several hormones. The pineal gland hormones affect secretion of hormones from the ovaries and a person’s sleep-wake cycle.

Our next gland is the parathyroid gland, which is the gland that surrounds the thyroid glands. The parathyroid gland is composed of four tiny glands that secrete PTH, which controls the blood calcium levels, allowing the muscular and nervous systems to function optimally. Parathyroid action is controlled by changes in calcium levels in the blood and does not change in response to another gland.

The pancreas is the flat gland attached to the small intestines behind the stomach that regulates blood glucose levels. Activation of the pancreas is controlled by detection of changes in blood glucose levels. Maintaining blood glucose levels is vitally important in order for the body to function as it should.

The final gland we are going to discuss is the thymus. The thymus is a two-lobed gland located in the upper chest between the lungs. Now that you are an adult, you don’t have any use for this gland, and in fact, it has diminished since you hit puberty. A group of hormones are released by the thymus that make the T-cells of the immune system develop. This gland is of the utmost importance in causing the immune system to develop.

Types of Hormones

Glands are one part of the endocrine system, but the other components of this system are the hormones. There are various types of hormones.

Steroid hormones are the cholesterol-based chemical messengers. Some steroid hormones make up sex hormones and others are classified as corticosteroids that are released by the adrenal cortex. There are also synthetic male sex hormones called anabolic steroids. Anabolic steroids have the same effect in the body as the male sex hormone.

The last type of hormone is the neurohormone. These are hormones that are released by the nervous system that are able to affect glands in the endocrine system.

Lesson Summary

You should have some insight into the endocrine system at this point. This is the body system that communicates and controls functions in the body. We learned that chemical messengers are hormones. Glands are groups of cells or an organ that secrete substances. We looked at leptin, the hormone that lets you know you are full, as an example of a hormone. This is also called the satiety hormone.

The two glands in the brain that control other glands are the hypothalamus and pituitary gland. The hypothalamus is the gland in the brain that controls the actions of almost all other glands. The pituitary gland is the gland below the hypothalamus that controls most other glands in the rest of the endocrine system. This is divided into the anterior and posterior pituitary glands.

We then covered the following glands that are controlled by the anterior pituitary gland:

  • Thyroid gland – the gland in the neck between the larynx and trachea that controls metabolism
  • Adrenal glands – the glands that sit on top of the kidneys that control blood pressure, the immune system, energy conversion, and stress
  • Gonads or sex glands – glands that secrete sex hormones
  • Ovaries – female gonads that control the female reproductive cycle and puberty
  • Testes – male gonads that cause development from male body characteristics

The other glands covered in this lesson include:

  • Pineal gland – gland in the brain that secretes several hormones in response to the optic nerve
  • Parathyroid gland – gland surrounding the thyroid gland that controls blood calcium
  • Pancreas – gland attached to the small intestines that regulates blood glucose levels
  • Thymus – gland in the upper chest between the lungs that causes development of T-cells

The last thing that we discussed that you should now know are the types of hormones. Steroid hormones are cholesterol-based chemical messengers. Anabolic steroids are synthetic male sex hormones, and neurohormones are hormones released by the nervous system.

Lesson at a Glance

The endocrine system is responsible for communicating and controlling functions throughout the body. With the help of glands, hormones are released that sends messages to start, stop, or continue a particular function.

Much like a factory line, glands throughout the body help with regulation of bodily functions.

Learning Outcomes

After reviewing this lesson, you should be able to:

  • Identify the function of the endocrine system
  • Name glands controlled by the hypothalamus and by the pituitary gland
  • Describe the function of other glands in the body
  • Explain the function of hormones

Medical Disclaimer: The information on this site is for your information only and is not a substitute for professional medical advice.

Endocrine System Information

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The endocrine system helps regulate and maintain various body functions by synthesizing (making) and releasing hormones, chemical messengers. The major areas of control and integration include responses to stress and injury, growth and development, absorption of nutrients, energy metabolism, water and electrolyte balance, reproduction, birth, and lactation. The endocrine system is composed of glands that release their hormones directly into the bloodstream for chemical signaling of target cells. These glands include the pituitary gland, the pineal gland, the hypothalamus, the thyroid gland, the parathyroid glands, the thymus, the suprarenal (adrenal) glands, the ovaries (in females) or testes (in males), and the pancreas.

Typically, the body synthesizes hormones in one part and transports it to another through the bloodstream or lymph. Endocrine glands have a rich blood supply through which hormones travel to reach their target organs. Hormones alter the metabolism of target organs by increasing or decreasing their activity. These changes in activity are strictly balanced to maintain homeostasis (a stable internal environment).

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Glands and neural components

Glands are of two types. Endocrine glands do not have a duct system and are called ductless glands. These glands release hormones directly into the blood or lymph. Exocrine glands such as the sudoriferous (sweat) glands contain ducts. Ducts are tubes leading from a gland to its target organ.

The endocrine system and the nervous system are so closely associated that they are collectively called the neuroendocrine system. Neural control centers in the brain control endocrine glands. The main neural control center is the hypothalamus, also known as the “master switchboard.” Suspended from the hypothalamus by a thin stalk is the pituitary gland. The hypothalamus sends messages to the pituitary gland; the pituitary gland, in turn, releases hormones that regulate body functions.

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Homeostatic feedback mechanisms

Many endocrine glands are linked to neural control centers by homeostatic feedback mechanisms. The two types of feedback mechanisms are negative feedback and positive feedback. Negative feedback decreases the deviation from an ideal normal value, and is important in maintaining homeostasis. Most endocrine glands are under the control of negative feedback mechanisms.

Negative feedback mechanisms act like a thermostat in the home. As the temperature rises (deviation from the ideal normal value), the thermostat detects the change and triggers the air-conditioning to turn on and cool the house. Once the temperature reaches its thermostat setting (ideal normal value), the air conditioning turns off.

An example of negative feedback is the regulation of the blood calcium level. The parathyroid glands secrete parathyroid hormone, which regulates the blood calcium amount. If calcium decreases, the parathyroid glands sense the decrease and secrete more parathyroid hormone. The parathyroid hormone stimulates calcium release from the bones and increases the calcium uptake into the bloodstream from the collecting tubules in the kidneys. Conversely, if blood calcium increases too much, the parathyroid glands reduce parathyroid hormone production. Both responses are examples of negative feedback because in both cases the effects are negative (opposite) to the stimulus.

Positive feedback mechanisms control self-perpetuating events that can be out of control and do not require continuous adjustment. In positive feedback mechanisms, the original stimulus is promoted rather than negated. Positive feedback increases the deviation from an ideal normal value. Unlike negative feedback that maintains hormone levels within narrow ranges, positive feedback is rarely used to maintain homeostatic functions.

An example of positive feedback can be found in childbirth. The hormone oxytocin stimulates and enhances labor contractions. As the baby moves toward the vagina (birth canal), pressure receptors within the cervix (muscular outlet of uterus) send messages to the brain to produce oxytocin. Oxytocin travels to the uterus through the bloodstream, stimulating the muscles in the uterine wall to contract stronger (increase of ideal normal value). The contractions intensify and increase until the baby is outside the birth canal. When the stimulus to the pressure receptors ends, oxytocin production stops and labor contractions cease.

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Pituitary gland

The pea-size pituitary gland is called the “master gland” because it regulates many key functions. The pituitary gland has an adenohypophysis (anterior lobe) and a neurohypophysis (posterior lobe). The adenohypophysis produces and secretes seven hormones in response to commands from the hypothalamus:

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

The TSH, ACTH, FSH, and LH hormones are tropic hormones that simulate other endocrine glands. In response, the other endocrine glands produce hormones that affect metabolism. For example, TSH from the pituitary gland stimulates the thyroid gland to produce thyroid hormones. In turn, thyroid hormones inhibit the release of calcium in the blood.

Other adenohypophysis hormones have unique effects upon metabolism. ACTH acts upon the cortex (outer area) of the suprarenal (adrenal) gland to produce steroid hormones. FSH and LH act upon women and men in regulating various sexual characteristics.

Prolactin and growth hormone act upon certain body tissues; they do not affect specific organs. Prolactin travels to the breast tissue glands of nursing mothers, causing milk production. Growth hormone stimulates protein synthesis and cell division in cartilage and bone tissue. Gigantism results when excessive amounts of growth hormone are produced during childhood. Pituitary dwarfism occurs when too little growth hormone is produced. Acromegaly occurs when too much GH is produced during adulthood.

Neuron cell bodies of the hypothalamus produce two hormones: antidiuretic hormone (ADH) and oxytocin. These hormones are transported along the axons to the axon terminals in the pituitary posterior lobe. Both hormones are stored in the terminals until they are released into the blood vascular network surrounding the posterior pituitary gland.

ADH acts upon the kidney tubules to help maintain a constant level of body water. This level is accomplished by increasing the water reabsorption amount when body water levels are low. Oxytocin triggers milk release from breast tissue when infants nurse and causes muscle contractions in the uterus during labor.

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Thyroid gland

The thyroid gland has two lobes connected by an isthmus (small connecting stalk) and is in the lower part of the neck just below the larynx. The thyroid gland produces three hormones:

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

T3 and T4 are collectively called thyroid hormone and are produced in the follicles (hollow spherical structures) of the thyroid gland. Thyroid hormone affects body growth, metabolic rates, and the development of bones and skeletal muscle. Thyroid hormone also increases the sensitivity of the cardiovascular system to sympathetic nervous activity. This effect helps maintain a normal heart rate.

Parafollicular cells (C cells) between the thyroid gland follicles produce calcitonin. Calcitonin lowers blood calcium levels.

The parathyroid glands are embedded in back of the thyroid gland and secrete PTH (parathyroid hormone). PTH increases blood calcium by stimulating bone calcium release into the bloodstream and by increasing the calcium absorption rate in the gastrointestinal tract and kidneys.

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Suprarenal (adrenal) glands

The suprarenal (adrenal) glands are on top of each kidney. Each gland has a cortex (outer region) and a medulla (inner region). The cortex secretes glucocorticoids such as cortisol, mineralocorticoids, and small amounts of androgens and estrogens responsible for some secondary sex characteristics. Glucocorticoids raise blood sugar levels by increasing gluconeogenesis (synthesis of glucose from amino acid). This action ensures glucose supplies for the body when it is under stress. Mineralocorticoids such as aldosterone promote sodium (salt) reabsorption by stimulating the kidneys to absorb more sodium from the blood.

The medulla “emergency gland” develops from nervous tissue; the autonomic nervous system controls its secretions. The medulla secretes epinephrine (adrenaline) and norepinephrine (noradrenaline), chemicals that raise the blood levels of sugar and fatty acids. These hormones also increase the heart rate and force of contraction. These effects prepare the body for the “Fight or Flight” response (instant physical activity), enabling the individual to think quicker, fight harder, and run faster. These hormones also constrict the blood vessels supplying the skin, kidneys, gastrointestinal tract, and other areas of the body not needed for the response.

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Ovaries and testes

The ovary is the site of estrogen and progesterone synthesis. Estrogen is required to form the ovum (egg) during oogenesis and prepares the uterus for implanting a fertilized egg. Progesterone prepares the breasts for lactation during pregnancy and works with estrogen to regulate the menstrual cycle.

The testes produce the hormone testosterone. Testosterone is required for sperm formation during spermatogenesis, the development of male external genitalia, and secondary sexual traits such as beard growth, chest hair, and enlarged thyroid cartilage.

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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.

Glossary | Endocrine Society

Improve your understanding of technical medical and scientific terms with our endocrinology glossary. We provide definitions and understandable explanations of key terms.

Acromegaly—Acromegaly is a hormonal disorder where the pituitary gland produces excess amounts of growth hormone.

Adrenal Cortex—The adrenal cortex is the outer portion of the adrenal gland and it produces steroid hormones, which regulate carbohydrate and fat metabolism, and mineralocorticoid hormones, which regulate salt and water balance in the body.

Adrenal Glands—Adrenal glands are triangle-shaped glands that sit on top of the kidneys. They regulate stress response through the synthesis of hormones, including cortisol and adrenaline.

Adrenaline—Adrenaline is a hormone that triggers the body’s fight-or-flight response. It is produced in the medulla in the adrenal glands as well as some of the central nervous system’s neurons.

Adrenocorticotropin (ACTH)—Adrenocorticotropin is a hormone produced by the anterior pituitary gland that stimulates the adrenal cortex.

Amenorrhea—Amenorrhea is the term used when a woman or adolescent girl is not having menstrual periods.

Androgens—Androgens are hormones that help to develop sex organs in men. They also contribute to sexual function in men and women.

Andropause—Andropause is a biological change characterized by a gradual decline in androgens experienced by men during and after their mid-life. Andropause is sometimes inaccurately described as male menopause.

Angiotensin—Angiotensin is the common name of four hormones: angiotensin I-IV, which play an important role in the body’s overall health and blood pressure regulation.

Antiandrogens—Antiandrogens are substances that inhibit the biological effects of androgenic hormones. 

Benign Prostatic Hyperplasia (Enlarged Prostate)—Benign prostatic hyperplasia is non-cancerous enlargement of the prostate gland, a common occurrence in older men.

Bioavailable Testosterone—Bioavailable testosterone represents the fraction of circulating testosterone that readily enters cells and better reflects the bioactivity of testosterone than does the simple measurement of serum total testosterone.

Bioidentical Hormones—Bioidentical hormones are compounds that have exactly the same chemical and molecular structure as hormones that are produced in the human body. Though any hormone can be made to be “bioidentical,” the term is often used to describe allegedly custom-compounded formulations containing estrogens, progesterone, and androgens. There is no evidence that they are any safer or more effective than FDA-approved hormone preparations.

Bone Mineral Density—A bone mineral density (BMD) test measures the density of minerals (such as calcium) in bones using a special X-ray, computed tomography (CT) scan, or ultrasound. This information is used to estimate the strength of bones.

Calcitonin—Calcitonin is a protein hormone secreted by cells in the thyroid gland. It inhibits cells that break down bone and helps to regulate the blood’s calcium and phosphate levels.

Cholescystokinin—Cholecystokinin, otherwise known as CCK or CCK-PZ, is able to improve digestion and affects appetite.

Cholesterol—Cholesterol is a white crystalline substance found in animal tissues and various foods that is normally synthesized by the liver. Cholesterol levels can be a risk factor for heart disease.

Congenital Adrenal Hyperplasia—Congenital adrenal hyperplasia refers to a group of inherited adrenal gland disorders. People with this condition do not produce enough of the hormones cortisol and aldosterone, and produce too much of androgen.

Cortisol—Cortisol is a hormone produced by the adrenal gland. It is involved in the stress response and increases blood pressure and blood sugar levels.

Cushing Syndrome—Cushing syndrome is a hormonal disorder caused by prolonged exposure of the body’s tissues to high levels of the hormone cortisol. Sometimes called “hypercortisolism,” it is relatively rare and most commonly affects adults aged 20 to 50.

Diabetes—Diabetes is a disease in which blood glucose levels are above normal. The body of a person with diabetes either doesn’t make enough insulin or can’t use its own insulin as well as it should.

Dehydroepiandrosterone—Dehydroepiandrosterone (DHEA) is the highest circulating steroid present in the human body. It is a precursor hormone that can be converted into hormones such as testosterone and estradiol.

Dihydrotestosteronemdash;Dihydrotestosterone is a male hormone more potent than testosterone that is converted from testosterone within the prostate.

Endocrine-disrupting Chemicals—Endocrine-disrupting chemicals (EDCs) are natural and man-made chemicals that can either mimic, block, or disrupt the action of hormones. EDCs are associated with numerous adverse human health issues, including reproductive health problems, obesity, diabetes, hormone-related cancers, neurological issues, and other disorders.

Endocrinologist—Endocrinologists are specially trained physicians who diagnose diseases related to the glands. Because these doctors specialize in these conditions, which can be complex and have

hard-to-spot symptoms, an endocrinologist is your best advocate when dealing with hormonal issues.

Erectile Dysfunction (ED)—Erectile dysfunction is the inability to achieve penile erection or to maintain an erection until ejaculation.

Erythropoietin—Erythropoietin is a hormone directly connected to red blood cell production and maintenance. Low levels of this hormone occur when someone has chronic kidney diseases.

Estradiol—Estradiol, a type of estrogen, is a female sex hormone produced mainly by the ovaries. It is responsible for growth of breast tissue, maturation of long bones, and development of the secondary sexual characteristics.

Estrogen—Estrogens are a group of steroid compounds that are the primary female sex hormones. They promote the development of female secondary sex characteristics and control aspects of regulating the menstrual cycle.

Estrogen Therapy (ET)—Estrogen therapy is a hormone therapy treatment program in which women take estrogen orally, transdermally, or vaginally to treat certain menopausal symptoms. 

Estrone—Produced by the ovaries, the estrone hormone is one of three types of estrogen. It is a weaker estrogen, commonly found in higher quantities in postmenopausal women.

Free Testosterone—Free testosterone is testosterone in the body that is biologically active and unbound to other molecules in the body, such as sex hormone binding globulin.

Follicle Stimulating Hormone (FSH)—In women, FSH helps control the menstrual cycle and the production of eggs by the ovaries. The amount of FSH varies throughout a woman’s menstrual cycle and is highest just before she ovulates. Problems with FSH release can contribute to female infertility. In men, FSH helps control the production of sperm.

Gastrin—Gastrin is a hormone the stomach produces. When you eat, gastrin stimulates the release of gastric acid, an important part of the digestive process.

Ghrelin —Ghrelin is central to appetite and the release of growth hormone. Produced in the stomach and small intestine, ghrelin has been called the “hunger hormone” because of its role in controlling appetite.

Glands—Glands produce and secrete hormones that the body uses for a wide range of functions. These control many different bodily functions, including respiration, metabolism, reproduction, sensory perception, movement, sexual development, and growth.

Glucagon—Glucagon is a hormone that works with other hormones and bodily functions to control glucose levels in the blood. It comes from alpha cells found in the pancreas and is closely related to insulin-secreting beta cells, making it a crucial component that keeps the body’s blood glucose levels stable.

Glucagon-Like Peptide 1 – Glucagon-like peptide 1 (GLP-1) helps regulate your appetite, especially after eating. It also helps enhance the production of insulin.

Gonads—A gonad is an organ that produces sperm and egg cells known as gametes. The gonads in males are the testes, and the gonads in females are the ovaries.

Graves Disease—Graves disease is the most common form of hyperthyroidism. It occurs when your immune system mistakenly attacks your thyroid gland and causes it to overproduce the hormone thyroxine.

Growth Hormone—Growth hormone is a substance that controls your body’s growth. Growth hormone is made by the pituitary gland, located at the base of the brain. Growth hormone helps children grow taller, increases muscle mass, and decreases body fat.

Gynecomastia—Gynecomastia is breast enlargement in boys or men due to a benign increase in breast tissue. This condition results from an imbalance between the hormones testosterone and estrogen.

Hirsutism—Hirsutism is excessive “male” pattern hair growth that appears on the face, back, chest, abdomen, and thighs in women.

Hormones—Made by endocrine glands, hormones are chemical messengers that travel in the bloodstream to tissues or organs. They affect many processes, including growth, metabolism, sexual function, reproduction, and mood.

Hormone Therapy—Hormone therapy is the use of hormones in medical treatment. For example, doctors may use hormone therapy to boost estrogen levels in menopausal women. Other examples include thyroid hormone replacement for thyroid deficiency, insulin therapy for diabetes, and transgender hormone therapy.

Hot Flashes—Hot flashes refer to the sudden wave of mild or intense body heat caused by dilation of capillaries in the skin resulting from decreased levels of estrogen. Hot flashes affect about 75 percent of women as they go through menopause.

Human Chorionic Gonadotropin Hormone—The human chorionic gonadotropin (hCG) hormone is important in the early stages of pregnancy. It is produced by cells that are surrounding a growing embryo, which eventually forms the placenta.

Hypoglycemia—Hypoglycemia, also called low blood sugar, occurs when your blood glucose level drops too low to provide enough energy for your body’s activities. Patients with severe hypoglycemia may experience unconsciousness or seizures due to low blood sugar.

Hypogonadism—Hypogonadism, or low testosterone, occurs when a man’s testes fail to produce sufficient quantities of testosterone and/or sperm quality is impaired.

Hypothalamus—The hypothalamus is an area of the brain that regulates vital autonomic centers and produces hormones that control thirst, hunger, body temperature, sleep, moods, sex drive, and the release of hormones from various glands, primarily the pituitary gland.

Insulin—Insulin is a protein pancreatic hormone involved in the metabolism of carbohydrates and the regulation of glucose levels in the blood. Diabetes occurs when the body doesn’t produce enough insulin or use the hormone effectively.  

IGF-1—IGF-1, or insulin-like growth factor 1, is a polypeptide protein hormone similar in molecular structure to insulin. It plays an important role in childhood growth and continues to have anabolic effects in adults. IGF-1 has been identified as a performance-enhancing drug.

Kallmann Syndrome—Kallmann syndrome is form of hypogonadism that is caused by congenital gonadotropin-releasing hormone (GnRH) deficiency. It is more common in males and is a known cause of delayed puberty. 

Kisspeptin – Kisspeptin, made in the hypothalamus, starts the reaction that signals the release of hormones involved in testosterone and estradiol production. Also called metastin, this hormone is connected to puberty and fertility, and it may also help stop the spread of cancer.

Klinefelter Syndrome—Klinefelter syndrome is the most common congenital abnormality in males causing primary hypogonadism, occurring in approximately 1 in 1000 live male births. This syndrome is the clinical manifestation of a male who has an extra X chromosome.

Leptin—Leptin, a hormone released from the fat cells located in adipose tissues, sends signals to the hypothalamus in the brain. This hormone helps regulate and alter long-term food intake and energy expenditure to help the body maintain its weight.

Luteinizing Hormone—Luteinizing hormone—also known as lutropin—is necessary for proper reproductive function. In women, it triggers ovulation.

Melatonin—Melatonin is essential to signaling the relaxation and lower body temperature that help with restful sleep. Melatonin is created by the pineal gland in the brain.

Menopause—Menopause is the process a woman goes through that causes her monthly periods to end. During menopause, a woman’s ovaries stop producing eggs and produce fewer female hormones.

Metabolic Syndrome—Metabolic syndrome describes a cluster of metabolic risk factors that increase the chances of developing heart disease, stroke, and diabetes. Genetic factors, too much body fat, and lack of exercise contribute to the development of the condition.

Norepinephrine—Norepinephrine is a hormone produced by the adrenal glands. It also acts as a neurotransmitter, a chemical messenger which transmits signals across nerve endings in the body. Together with other hormones, it helps the body respond to stress and exercise.

Obesity—Obesity is a chronic medical disease of having too much body fat. Health care providers diagnose obesity using a number called the body mass index.

Osteoporosis—Osteoporosis is a disease in which bones become weak and are more likely to fracture or break.

Ovaries—Ovaries are the egg producing organs found in females. They produce the hormones estrogen and progesterone.

Oxytocin—Oxytocin is a hormone that acts as a neurotransmitter in the brain. It facilitates birth and breastfeeding.

Pancreas—The pancreas gland secretes insulin, a hormone that helps glucose move from the blood into the cells to be used for energy. The pancreas also secretes glucagon when blood sugar is low.

Parathyroid—The parathyroid gland helps control both calcium and phosphorous levels and are necessary for proper bone development. The parathyroid gland is actually a group of four small glands located behind the thyroid gland.

Parathyroid Hormone – Parathyroid hormone plays a role in regulating blood calcium levels, helping the body maintain adequate calcium stores in the bloodstream to protect bone health. It comes from four parathyroid glands in the neck, just behind the thyroid.

Peptide YY—After eating, the hormone peptide YY (PYY) is produced by the small intestine and released into the bloodstream. PYY communicates to your brain that you are full and decreases your appetite.

Perimenopause—Part of the menopause transition, the perimenopause stage takes place when a woman’s ovaries gradually begin to produce less estrogen.

Pineal Gland—The pineal is a small endocrine gland located in the center of the brain between the two hemispheres. It secretes melatonin, which helps regulate wake/sleep patterns.

Pituitary Gland—The pituitary is a small endocrine gland located at the base of the skull. It helps control growth, blood pressure, breast milk production, and metabolism.

Polycystic Ovary Syndrome (PCOS)—Polycystic ovary syndrome (PCOS) is common hormone disorder that affects 7 to 10 percent of women. Signs include excess male hormones called androgens, problems with ovulation, and small follicles appearing on the ovaries.

Prader-Willi Syndrome—Prader-Willi syndrome is a genetic disorder that can cause a growth hormone deficiency. It is marked by a preoccupation with food, small stature, and learning difficulties.

Premenstrual Syndrome—Premenstrual syndrome describes the appearance of physical and emotional symptoms during the second half of the menstrual cycle.

Progesterone—Progesterone is a female hormone that signals the uterus to prepare for receiving an egg following fertilization. When progesterone levels go down each month, this causes the bleeding associated with menstrual periods.

Progestin—This is a synthetic form of progesterone. This class of drugs was originally developed to allow absorption by mouth for use in birth control pills.

Prolactin—Prolactin is a peptide hormone that promotes breast milk production.

Prostaglandins—Prostaglandins are a group of lipids involved in the process of inflammation and blood clotting following an injury. These hormones are created during a chemical reaction at the injury site.

Relaxin—Relaxin is a reproductive hormone secreted in the ovary by the corpus luteum. It is involved in preparing a pregnant woman’s body for labor and birth.

Serotonin&mdashSerotonin is the key hormone that stabilizes our mood, feelings of well-being, and happiness. It also helps reduce depression, regulate anxiety, and maintain bone health.

Somatostatin—Somatostatin—also called SS, SST or SOM—is a growth hormone inhibitory hormone. Somatostatin prevents the production of other hormones and stops the unnatural rapid reproduction of cells—such as those that may occur in tumors.

Steroids—Steroids are any of various molecules—including hormones—that contain a particular arrangement of carbon rings. Some common steroids include sex steroids, corticosteroids, anabolic steroids, and cholesterol.

Testes—Testes are the male reproductive organs. They produce sperm and the hormone testosterone.

Testosterone—Testosterone is a steroid, androgen hormone, and the primary male sex hormone. It is produced by the testes in men and ovaries in women, and it plays key roles in libido, energy, and immune function in both men and women.

Thymus—The thymus gland is located in the chest just behind the sternum. The thymus secretes hormones that are commonly referred to as humoral factors and are important during puberty. The role of these hormones is to make sure a person develops a healthy immune system.

Thyroid—The thyroid gland is located inside the neck. It regulates metabolism, which is the body’s ability to break down food and convert it to energy. Thyroid disorders typically result when the gland releases too little or too much thyroid hormone.

Thyroid-stimulating hormone—Thyroid-stimulating hormone (TSH) stimulates the thyroid to secrete the hormones thyroxine and triiodothyronine. It is manufactured by the hypothalamus and transported by the anterior pituitary gland.

Thyroxine—Thyroxine, also known as T4, plays a crucial role in heart and digestive function, metabolism, brain development, bone health, and muscle control. The thyroid gland secretes thyroxine into the bloodstream.

Total testosterone—Total testosterone is a measurement of the total amount of testosterone in the blood, combining free testosterone and testosterone bound to certain molecules and already at use in the body.

Turner Syndrome—Turner syndrome occurs in females when one of the X chromosomes is missing or damaged. The most common features of Turner syndrome are short stature and reduced or absent development of the ovaries. As adults, women with this disorder are typically infertile.

Vitamin D—Vitamin D is a prohormone—a substance the body converts to a hormone. The body produces vitamin D in a chemical reaction that occurs when sunlight hits the skin, and some vitamin D also comes from food sources. Active vitamin D functions as a hormone because it sends messages to the intestines to increase the absorption of calcium and phosphorus.

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Endocrine system

The endocrine system regulates the functions of internal organs. This regulation is carried out by hormones secreted by endocrine cells directly into the blood or carried to neighboring cells through the cell membrane. Endocrinology studies all of these processes.

The endocrine system is distinguished into glandular and diffuse. Glandular is when the endocrine glands are “scattered” throughout the body.Diffuse is already endocrine cells, which are also “scattered” throughout the body. Endocrine cells “divide” with the body hormones – aglandular peptides.

Of course, the functions of the endocrine system are vitally important to humans. It participates in the chemical regulation of organs, systems and the body as a whole.

It participates (along with the immune and nervous system) in the growth and development of the body, in sexual differentiation, controls reproductive function and energy conservation.

Hormones produced by the endocrine system , along with the nervous system play an important role in the psychoemotional state of a person.

What are these hormones? Hormones – couriers, entering the bloodstream, deliver chemicals to cells throughout the body. As already mentioned, hormones are produced in the endocrine glands and are proteins, steroids, or protein derivatives.

As it became known, hormones are also produced by organs – heart, liver, brain.

Today we are familiar with more than 60 hormones, most of which cannot be stored in the body in reserve, with the exception of thyroglobulin produced by the thyroid gland, which can be stored for 2 days, as well as vitamin D, which is stored in the liver in reserve.

For the body to function normally, hormones must be constantly produced. How many hormones the endocrine glands will produce directly depends on the state of the physical, mental, age, as well as the time of day.

Some types of hormones enter the bloodstream in pulses. Hormones, synthesized in one place and entering the bloodstream, are transported to cells throughout the body. Some hormones are characterized by “moving” to “their” target cells by attaching to transport proteins, carrier proteins.

Hormones are excreted from the body in their original form with urine and bile. The main amount of hormones is processed in the liver and leaves the body with bile.

The hypothalamus is the center of regulation of hormone production by endocrine glands and their release into the blood.It is located in the brain, it is in it that hormones called liberins are formed – stimulants of another central endocrine organ – the pituitary gland. Liberins “come” to the pituitary gland from the hypothalamus and stimulate the production of its own hormones by the pituitary gland – tropines. Tropines, in turn, stimulate the production of hormones by the endocrine glands, which are the main link acting in the entire chain.

In this case, the hormones produced by the endocrine glands contribute to the normal functioning of the hypothalamic-pituitary system.When the concentration of hormones in the blood rises, liberins by the hypothalamus are “released in reduced circulation”, which leads to a decrease in the production of tropes by the pituitary gland, and this becomes a consequence of a decrease in the production of the hormone. Thus, the hormone itself regulates its own production.

The scheme described above does not include a description of the entire complex system of regulation of hormonal work in the body, since there is a wide range of significant factors. When work is needed and the amount of hormones is regulated very quickly.

Manifestation in the function of hormones of disorders is possible in the following cases:

  • Lack of hormone. With a reduction in the production of hormones by the endocrine gland, a heart attack may occur as a result, infections, autoimmune processes, hereditary diseases become more active, tumors may appear.
  • Excessive production of the hormone with its subsequent release into the blood is observed in the case of excessive synthesis of their endocrine glands, as well as when the hormone begins to be produced by tissues (maybe with malignant degeneration), an increased release of hormones from the precursor by tissues can also be observed.An iatrogenic cause of an increase in the hormone in the blood is considered to be the case when a hormone in the form of a medicine is injected into the body in excess.
  • Synthesis of abnormal hormones by the endocrine glands, which is explained by the presence of genetic abnormalities.
  • Resistance (immunity) to hormones, which manifests itself in an inadequate response of body tissues to normal or increased hormone levels. Causes: heredity, tissue receptor defects, production of antibodies to hormones by the body.

Endocrine glands:

1.The pituitary gland is a special gland, as it not only produces hormones, but also affects their production by other glands in the same organism. The pituitary gland is located at the base of the brain and is connected to the hypothalamus by a group of nerve fibers. Together (the pituitary gland and the hypothalamus) control metabolic processes throughout the body, thereby providing all organs with the necessary substances for full activity.

2. The thyroid gland is located at the level of the larynx.

3.The parathyroid glands, which are located next to the thyroid gland.

4. The pancreas is the largest of all. She is two glands in one. Insulin is a hormone produced by the pancreas, diseases due to malfunctioning of the pancreas can be serious, one of which is diabetes. Diseases characteristic of the pancreas are acute pancreatitis, chronic pancreatitis, tumor, lipomatosis. If problems arise with the pancreas, treatment should be started on time, in order to avoid the development of irreversible processes or the transition of the disease into a chronic form. In any case, for problems with the pancreas, treatment is supplemented by a strict diet.

Violations in any zone of the endocrine system can lead to many disorders of the processes in the body. Endocrinology is a branch of medicine dealing with the study of the endocrine system. It is possible to monitor the state of ES, carry out prophylaxis, diagnose diseases and treat them under the supervision of an endocrinologist. A good endocrinologist will help diagnose the disorder itself and the cause of the disorders in the functioning of the ES and select the right treatment.

Endocrinology in Irkutsk and consultation with a good endocrinologist are available at the For the Whole Family clinic. Qualified specialists of our clinic will be able to provide detailed consultation, examination and treatment.

Price list for the services of an endocrinologist

You can make an appointment at any time convenient for you and receive detailed advice from a specialist:

1) by phone. : +7 (3952) 390 – 292; 404 – 200 (Railway 2nd, 74)

2) by phone: +7 (3952) 205-749; 723 – 749 (Karl-Liebknecht, 152)

90,000 Endocrine system. Norm and pathology

The endocrine system as a natural phenomenon

The endocrine system, it is also the system of neurohumoral regulation (literally “neuro-fluid control”), is extremely complex. Its structure, composition and functioning are, apparently, at the limit of what, in principle, can be investigated and comprehended by modern science, armed with a powerful (as it seems to it) instrumental, laboratory-analytical and computational arsenal.A whole branch of medicine, called endocrinology, deals with the study of this system, its normal operation, its various dysfunctions and diseases, as well as methods of treating the latter. An entire sector of pharmacology is engaged in the development, synthesis and improvement of the so-called. hormone-containing drugs; despite the chronic problem of side effects, it is no longer possible to do without this group of drugs.

Organs (glands), tissues or cells of a certain type related to the endocrine system, for example, Kulchitsky’s cells in the intestinal mucosa, produce special organic compounds that are usually called bioactive regulators, neurotransmitters, signaling biochemical substances, but more often just hormones.This word is translated from Greek means “to excite”, “to induce” or, in more modern language, “to activate”. Hormones go directly into the bloodstream; the slightest fluctuations in their concentration in living tissues are captured by specific receptor cells that are sensitive to one or another group of hormones and are able to respond to hormonal “commands” – for example, an increase in body temperature, a decrease in blood pressure in blood vessels, intense lactogenesis in the mammary glands, and many .other In this way, practically all physiological and mental processes in the body are triggered, forced, inhibited or completely suppressed – in a word, controlled.In this case, each gland, as a rule, secretes several hormones, and each hormone, in turn, affects several interrelated processes.

The synonymous term “neurohumoral regulation” does not accidentally contain the root “neuro-“. According to modern concepts, the endocrine system plays an important, exclusive role in the vital activity of the organism, but nevertheless it is not the “supreme power” in relation to it. Hierarchical primacy belongs to the central nervous system (CNS), i.e.e. to the brain and spinal cord. Hormones are responsible for everything, but the secretory activity of the endocrine glands themselves is controlled by special cerebral formations and appendages, – first of all, the hypothalamus-pituitary ligament in the lower region of the brain, in the so-called. diencephalon – using for this signal electrochemical impulses and a whole web of neural communication channels (in IT, such an internal network would be called an intranet). Given the above, endocrinology today is increasingly identified with neuroendocrinology (which was considered a separate field half a century ago), and a group of disorders previously traditionally called hormonal are interpreted as neuroendocrine diseases or dysfunctions.

It is difficult to say why the evolving mammals developed such a complex, multistage and multielement neuroendocrine system. As you know, nature cares most about expediency, and least of all about making it convenient for a person to study it. Nature always has a lot of possible ways and options; most likely, infinitely many. It would certainly be possible to regulate the vital activity of higher organisms in some other way, and preferably simpler. However, the following cannot be denied.A modern, reasonable and technological man is still very far from creating an artificial system similar to himself – a system as compact, energetically economical and efficient, with five autonomous sensor units and two universal manipulators at once; a system that optimally combines strength, flexibility and mobility, unconditioned and conditioned reflexes, consciousness and unconsciousness; in addition, the system is self-reproducing, to some extent self-learning and, most importantly, preserving homeostasis (constancy of internal conditions), i. e.That is, self-adapting to almost any external conditions. Therefore, today we can only admire, thank nature for our amazing endocrine system – and continue to persistently explore its countless mysteries.

Main endocrine glands

You can often find the expression “the main endocrine gland”, and in different sources this role is assigned to the pituitary gland, then the hypothalamus. No one knows what discoveries will be made tomorrow, so we restrict ourselves to a careful repetition of the above: as far as we know today, the activity of the neuroendocrine system (at least most of the endocrine glands) is controlled by a pair of hypothalamus-pituitary gland.In addition, the most important functions of the pituitary gland include the production of somatotropic hormone, which regulates the processes of growth and formation of the body.

Epiphysis (pineal gland of the brain)
is one of the central neuroendocrine regulators. It is a kind of brake or limiter that blocks the excessive “acceleration” of the endocrine glands. In particular, it normalizes the secretion of growth hormone and sex hormones, and prevents tumor processes.

Thyroid gland participates in the regulation of metabolism, primarily the assimilation of iodine and calcium; affects many dependent systems and processes (from general energy exchange and intellectual productivity to tissue regeneration of the musculoskeletal system).

Parathyroid (parathyroid) glands regulate the condition of bone and muscle tissues, intraocular structures, kidneys.

The adrenal glands produce, according to modern data, about fifty signaling substances. The most famous and studied functions are the provision of water-salt, carbohydrate, mineral, protein metabolism, the production of male and female sex hormones (along with the gonads). The famous glucocorticosteroid hormones produced by the adrenal cortex are not, of course, a panacea and can lead to numerous undesirable effects (especially when taken orally), but they often turn out to be the only “lifeline” due to their pronounced anti-inflammatory, anti-allergic, immunomodulatory, anti-shock and anti-shock and anti-shock and anti-shock effects. No less well-known are such bioregulators as adrenaline and norepinephrine (catecholamine hormones produced by the adrenal medulla).

special clusters of cells that can rightfully be called neuroendocrine: they are responsible for sensitivity, regulate chromium metabolism and simultaneously secrete catecholamines, like the adrenal glands.

The pancreas functionally belongs to the digestive system, but contains an insignificant (1-3% of the weight of the gland) volume of endocrine cells, which are concentrated, incl.n. islets of Langerhans and producing insulin – a hormone regulating blood glucose levels.

Testicles (in men), ovaries (in women) – secrete sex hormones (androgens and estrogens). The placenta also plays an endocrine role during gestation.

The thymus gland (thymus) produces mainly immunoregulatory hormones.

It should be noted that by now far from all the functions of the endocrine glands and the hormones produced by them are known; only the most important and explored ones are listed here.

Most common endocrine diseases

The number of independent diseases and syndromes associated with hormonal imbalance is today estimated at about six thousand. In other words, most of the diseases known to modern medicine (about ten thousand) are indeed hormonal. Some of them today threaten to become pandemic, others are sporadically rare; some are congenital and genetically determined, others are acquired during life under the influence of numerous etiopathogenetic factors (trauma, tumors, inflammation, etc.)etc.).

Diabetes mellitus seems to be the most common and well-known endocrine-metabolic disease. Thyroid pathology is also very common, in particular, endemic iodine deficiency states, hyperthyroidism, thyroiditis, and many others. etc. A pronounced negative effect on the whole organism, its formation, structure, appearance, functioning, – have anomalies and lesions of the glands that produce sex hormones, corticoids, somatotropin. Even the well-known premenstrual syndrome in women is nothing more than a transient, cyclically recurring and transient hormonal imbalance.

In general, endocrinology has to think truly globally and systemically, dealing with a huge number of cross-linked processes, normal and pathological. However, the diseases of this group, once completely incomprehensible, are now being successfully diagnosed and treated. It is only important to consult a doctor on time – that is, as early as possible – until the changes become irreversible.

90,000 Endocrine Diseases – Causes, Symptoms and Treatment.

Endocrine diseases.Where to get treatment in Nizhny Novgorod?

Endocrine diseases are treated by an endocrinologist in Nizhny Novgorod.

There are many endocrine diseases.

How to identify endocrine diseases in Nizhny Novgorod?

The symptoms of endocrine diseases are insidious and similar to other diseases.

The endocrine system in the human body regulates the work of internal organs through the production of special substances – hormones.

Hormones affect the physical parameters of a person, the mental and emotional state of a person and physiological processes in the human body.

You can determine the level of hormones in your body in Online Clinics!

If the work of the endocrine system fails, then the process of hormone production is disrupted: hormones are produced in a reduced or increased amount, the processes of transport or absorption of the hormone are disrupted, an abnormal hormone is produced, and resistance against hormonal action is developed.

Doctors – endocrinologists in Nizhny Novgorod state disturbances in the functioning of the human endocrine system, which lead to various diseases and hormonal imbalances:

  • Hypothyroidism is a disease that affects women more often than men. Hypothyroidism is characterized by hypothyroidism, in which insufficient hormones are produced. Hypothyroidism leads to a slowdown in metabolic processes. At the initial stage hypothyroidism can be recognized by a state of chronic fatigue.
  • Diabetes mellitus – a disease of complete or partial deficiency of insulin in the blood. Because of this, fats, proteins and carbohydrates are poorly absorbed, and incomplete breakdown of glucose occurs. Diabetes mellitus is life-threatening.
  • Goiter develops due to a violation of the production of thyroid hormones. The main reason for the development of goiter is considered to be a lack of iodine in food. Iodine is essential for the proper functioning of the thyroid gland.
  • Thyrotoxicosis – hyperfunction of the thyroid gland.
  • Autoimmune thyroiditis is a thyroid disease in which the immune system malfunctions.Thyroiditis causes the immune system to perceive thyroid cells as foreign.
  • Hypoparathyroidism leads to cramps in the limbs of a person due to malfunctioning of the parathyroid gland.
  • Hyperparathyroidism – also develops under the influence of malfunctioning of the parathyroid gland.
  • Gigantism is an overproduction of growth hormone that leads to increased but proportionate body development. In adults, the hyperfunction of this hormone provokes an increase in the size of certain parts of the body.

Symptoms of endocrine diseases, determined in Nizhny Novgorod by a doctor – endocrinologist.

The endocrine system includes all endocrine glands.

Among the main symptoms of endocrine diseases in Nizhny Novgorod, doctors – endocrinologists from the Onely Clinic name fatigue, muscle weakness, a sharp change in weight (gaining or losing weight with an unchanged diet), heart pain, heart palpitations, fever, sweating, overexcitation, drowsiness, problems with urination, constant feeling of thirst, high blood pressure, headaches, memory problems, stool disorder.

All these symptoms can be ignored by the patient for a long time, or can be mistaken for ordinary fatigue.

In the meantime, the disease can progress and problems with the immune and hormonal systems increase.

Only examination by a professional doctor – endocrinologist, passing the necessary tests for hormones will be able to establish the correct diagnosis and identify the cause of the ailment.

Why do endocrine diseases develop in Nizhny Novgorod?

There are people who are at risk for endocrine system diseases.

Endocrinologists in Nizhny Novgorod call the following risk factors:

  • Age , plus 40.
  • Heredity.
  • Overweight, obesity.
  • Incorrect and sometimes even harmful food.
  • Bad habits: smoking, alcohol, drugs.
  • Physical inactivity: sedentary lifestyle.

Identification of diseases of the endocrine system in Nizhny Novgorod.

Why do you need to contact Online Clinics?

It is impossible to identify an endocrine disease on your own.

Only a complex of examinations and analyzes will be able to correctly establish the diagnosis.

Therefore, it is imperative to consult an endocrinologist at the Only Clinic in Nizhny Novgorod when symptoms of endocrine disorders appear.

Doctor – endocrinologist Onli Clinic conducts a complex of examinations of the endocrine system of the human body, on the basis of which the diagnosis is established:

  1. Visual inspection.A good endocrinologist in Nizhny Novgorod can determine the presence of an endocrine disease by the patient’s appearance. Specifically, after examining the skin, the proportionality of body parts, skin pigmentation, enlargement of the thyroid gland, atypical hair growth.
  2. Palpation is required to determine the state of the thyroid gland
  3. The endocrinologist will definitely prescribe the patient to take blood tests for sugar and hormones.
  4. Ultrasound of the thyroid gland and ultrasound of the abdominal cavity are quite informative.
  5. In addition, X-ray, CT can be prescribed.

Many endocrine diseases are hereditary. This is due to mutations at the gene level.

There is a very high risk for a child to get sick if both or one parent is sick with any endocrine disease.

Endocrine diseases have implications for all human health.

Hormones play an essential role in both male and female organisms.

If the production of hormones is disrupted, this can lead to the most serious consequences for human health.

Disorders in the work of the endocrine system, in the work of the thyroid gland, hormonal imbalance lead to malfunctioning of internal organs, metabolic processes, functions of endocrine glands, the occurrence of somatic disorders and cosmetic defects.

At the slightest suspicion of an endocrine disease, an urgent need to consult an endocrinologist in Nizhny Novgorod.

The presence of an endocrine disease makes a person constantly dependent on taking medications and hormones.

Endocrine diseases can provoke the development of other “sores”.

Self-medication of endocrine diseases is life-threatening!

90,000 their structure, functions that produce

“The glands of fear and courage”, “fighters of the endocrine system” – such a contrasting metaphor in relation to these organs is quite understandable, because it is they who are directly involved in the formation of two basic human emotions – fear and anger. What are the adrenal glands, what is their role in the body, where are they located? Let’s try to figure it out.

Having attracted the attention of scientists for a long time, these endocrine glands were first described by the outstanding Italian physician and anatomist Bartolomeo Eustachius in the middle of the 16th century. Currently, science has detailed information about the structure and functions of the adrenal glands, but we probably do not know everything about them.

How are the adrenal glands arranged?

There are two adrenal glands (aka adrenal glands) in the human body.They are located in the retroperitoneal space in the lumbar region, and are small “caps” over the kidneys. Despite the fact that the role of the adrenal glands is the same, they have a different shape. The gland on the left is visually similar to a crescent, and the right one resembles a triangle.

Adrenal gland structure

Outside, the glands are covered with a connective tissue capsule. Looking at the cross-section of the gland, you can find two layers in it. The first is located on the periphery of the organ and is called the cortex.In the central region of the gland is the medulla.

To answer the question of which glands the adrenal glands belong to, it is enough to refer to their structure. The adrenal glands produce biologically active substances – hormones that go directly into the blood. The adrenal glands do not have excretory ducts, therefore these organs are referred to as endocrine glands.

The cortical substance makes up about 90% of the total mass of the glands. It is formed by cells that produce corticosteroid and sex hormones.

Three zones are distinguished in the cortical layer, differing from each other in the structure of their constituent cells.

1. Glomerular – occupies about 15% of the entire cortex. It consists of small cells collected in “glomeruli” and synthesizing mineralocorticoids – aldosterone, corticosterone, deoxycorticosterone. These hormones are involved in the regulation of blood pressure and water-salt balance.

2. Bundle – its structure is made up of long bundles of large cells that occupy two-thirds of the adrenal cortex.They produce glucocorticoids – hormones that affect immunity, suppress the growth of connective tissue, and also reduce the intensity of inflammatory, allergic reactions in the body. These include, in particular, cortisol and cortisone.

3. Mesh – consists of a thin layer of small cells of various shapes, forming a mesh structure. Here the formation of sex hormones occurs – androstenedione, DEASO4, which are responsible for the development of secondary sexual characteristics of a person, are important for bearing a fetus.

The medulla, located in the center of the adrenal glands, consists of chromaffin cells. Despite a small share in the total volume of the glands, it is the cells of the medulla that produce catecholamines – adrenaline and norepinephrine – which control the body’s work under stress.

What do we need the adrenal glands for?

For life. And these are not pompous words. The absolute importance of the adrenal glands is confirmed by the fact that when they are damaged or removed, death occurs.

The formation of hormones and biologically active substances that directly affect the growth, development and functioning of vital organs is the main function of the adrenal glands. Thanks to hormones produced by the adrenal medulla and cortex, various metabolic processes are regulated. In addition, they take part in the body’s immune defense, human adaptation to adverse external conditions and changing internal factors.

Today there are more than 50 steroid compounds produced only by the adrenal cortex.For example, hydrocortisone ensures the accumulation of glycogen in the liver and muscles, inhibits protein synthesis in some tissues and accelerates its formation in others. It also affects the metabolism of fats, inhibits the activity of lymphoid and connective tissues. Aldosterone is responsible for the regulation of water-salt metabolism, maintaining the ratio of sodium and potassium salts.

Cortisol stimulates the immune system. If the body is exposed to unforeseen stress, then this hormone begins to be produced urgently.Thanks to it, the work of the brain improves, the heart muscle is strengthened, the body acquires the ability to withstand various types of stress.

The amount of adrenaline and norepinephrine, which are produced by cells of the adrenal medulla, usually increases in stressful situations. Increasing the level of adrenaline in the blood helps to start the processes that mobilize the body and make it capable of surviving in adverse conditions. At the same time, breathing becomes more frequent, the flow of oxygen to the tissues accelerates, the level of sugar in the blood rises, the tone of the blood vessels and pressure.Due to the stimulating effect of these hormones, muscle strength, reaction speed, endurance and pain threshold increase. This allows you to respond to the threat with one of the options – “fight” or “flight”.

By regulating vital functions, the adrenal glands help us quickly adapt to changes in the environment. To reduce the risks of adrenal dysfunction, you should, if possible, avoid stress, be physically active, observe a work and rest regimen, eat right and consult a doctor in a timely manner when complaints appear and for preventive purposes.

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Endocrinology – search for specialists and doctors

What does endocrinology mean?

Endocrinology is a specialized field of medicine that mainly deals with hormones in the body and the endocrine glands, as well as their diseases. The term “endocrine” means “released by the inside”, which means a secret released into the blood.Exocrine glands, such as sweat glands, secrete their secretions through the excretory ducts from the body to the outside.

What are hormones?

Hormones are neurotransmitters that circulate throughout the body with blood and regulate the functions of various organs and cells. Hormones act on cells by binding to receptors on the cell membrane or inside the cell, and then activate and inhibit enzymes.

Hormones can cause the cell to read certain genes and produce more substances.Simply put, this phenomenon can be figuratively described as a key that fits the correct lock. Only cells that carry the appropriate receptor for the hormone respond to its signal.

Through this interaction, the body can adapt to different conditions. So hormones control metabolism, digestion, sleep, growth, pregnancy, stress and many other processes in the body.

What hormone-producing (endocrine) glands are there?

The most important endocrine organs are:

  • pineal gland (pineal gland)
  • pituitary
  • thyroid
  • parathyroid glands
  • adrenal glands
  • pancreas
  • ovaries and testes


(pineal gland) is a small gland in the brain that mainly produces melatonin, which controls the rhythm of sleep and wakefulness.


is a gland that connects to the brain through a specific section and receives many signals from the hypothalamus. The pituitary gland produces a variety of hormones that primarily serve to control other endocrine glands, and can be thought of as the control center of the hormonal system. It also produces growth hormone. An overactive pituitary gland, such as in a benign tumor, can lead to gigantism in childhood or acromegaly in adults.


– an endocrine organ that surrounds the trachea in the neck. The hormones triiodothyronine and thyroxine, which it produces, increase the metabolism and energy consumption of the body. They increase the strength and heart rate and play an important role in physical and mental development. The thyroid gland is stimulated by the pituitary gland and needs iodine from food to produce hormones. The most important diseases include hyperthyroidism, hypothyroidism, and thyroiditis. Over-activity of the gland causes anxiety, increased heart rate, weight loss and fever, while hypothyroidism leads to fatigue, low blood pressure, and weight gain.

Parathyroid glands

– small organs on the back of the thyroid gland. Most people have four. They produce parathyroid hormone, which affects blood calcium levels and therefore may also play a role in bone disease.


The gland is an endocrine and exocrine gland located in the abdomen.It not only produces hormones, but also secretes a secret for the digestive tract. The most important function of the pancreas is to regulate blood sugar levels. To do this, it can produce the hormone insulin (lowering blood sugar) and glucagon (raising blood sugar). If the production or action of insulin is disrupted, blood sugar levels remain elevated and cause long-term harm to the body. In this case, they talk about diabetes.

Adrenal glands

are small pyramidal glands that are located on the kidneys in the form of caps.They distinguish between the cortex and the medulla. In the adrenal cortex, glucocorticoids and mineralocorticoids are produced (Latin cortex = “bark”, “shell”). They regulate kidney function, stress and inflammation responses, blood pressure, and blood sugar levels. In addition, the adrenal cortex produces small amounts of androgens (such as testosterone). A well-known complex of symptoms with high cortisol levels due to medical treatment or adrenal diseases is Itsenko-Cushing’s disease. The adrenal medulla secretes the hormones adrenaline and norepinephrine, which make the body work under stress, fight or flight.


are located in the lower abdomen and communicate with the uterus through the fallopian tubes. They induce the development of female sexual characteristics through the hormones estrogen and progesterone and control the menstrual cycle and pregnancy. Estrogen affects blood clotting, bone clotting, and early growth arrest in women.


produce most of the androgens (male sex hormones), as well as small amounts of estrogen.