The Endocrine System and Glands of the Human Body: Function and Disorders

Written by Barbara Brody

• What Is the Endocrine System?
• What Is a Gland?
• Endocrine System Functions
• Parts of the Endocrine System
• Health Issues
• Endocrine System Disorders
• More

The endocrine system is a network of glands in your body that make the hormones that help cells talk to each other. They’re responsible for almost every cell, organ, and function in your body.

If your endocrine system isn’t healthy, you might have problems developing during puberty, getting pregnant, or managing stress. You also might gain weight easily, have weak bones, or lack energy because too much sugar stays in your blood instead of moving into your cells where it’s needed for energy.

A gland is an organ that makes and puts out hormones that do a specific job in your body. Endocrine and exocrine glands release the substances they make into your bloodstream.

Your endocrine system:

• Makes hormones that control your moods, growth and development, metabolism, organs, and reproduction
• Controls how your hormones are released
• Sends those hormones into your bloodstream so they can travel to other body parts

Many glands make up the endocrine system. The hypothalamus, pituitary gland, and pineal gland are in your brain. The thyroid and parathyroid glands are in your neck. The thymus is between your lungs, the adrenals are on top of your kidneys, and the pancreas is behind your stomach. Your ovaries (if you’re a woman) or testes (if you’re a man) are in your pelvic region.

• Hypothalamus. This organ connects your endocrine system with your nervous system. Its main job is to tell your pituitary gland to start or stop making hormones.
• Pituitary gland. This is your endocrine system’s master gland. It uses information it gets from your brain to tell other glands in your body what to do. It makes many important hormones, including growth hormone; prolactin, which helps breastfeeding moms make milk; antidiuretic hormone(ADH) (vasopressin), which controls blood pressure and helps control body water balance through its effect on the kidney, corticotropin /ACTH: Adrenocorticotrophic hormone. which stimulates the adrenal gland to make certain hormones, thyroid-stimulating hormone (TSH), which stimulates the production and secretion of thyroid hormones, oxytocin which helps in milk ejection during breast feeding; and luteinizing hormone, which manages estrogen in women and testosterone in men.
• Pineal gland. It makes a chemical called melatonin that helps your body get ready to go to sleep.
• Thyroid gland. This gland makes thyroid hormone, which controls your growth and metabolism. If this gland doesn’t make enough (a condition called hypothyroidism), everything happens more slowly. Your heart rate might slow down. You could get constipated. And you might gain weight. If it makes too much (hyperthyroidism), everything speeds up. Your heart might race. You could have diarrhea. And you might lose weight without trying. The thyroid gland also produces the hormone calcitonin, which may contribute to bone strength by helping calcium to be incorporated into bone.
• Parathyroid. This is a set of four small glands behind your thyroid. They play a role in bone health. The glands control your levels of calcium and phosphorus.
• Thymus. This gland makes white blood cells called T-lymphocytes that fight infection and are crucial as a child’s immune system develops. The thymus starts to shrink after puberty.
• Adrenals. Best known for making the “fight or flight” hormone adrenaline (also called epinephrine), these two glands also make hormones called corticosteroids. They affect your metabolism heart rate, oxygen intake, blood flow, and sexual function, among other things.
• Pancreas. This organ is part of both your digestive and endocrine systems. It makes digestive enzymes that break down food. It also makes the hormones insulin and glucagon. These ensure you have the right amount of sugar in your bloodstream and your cells.
• If you don’t make insulin, which is the case for people with type 1 diabetes, your blood sugar levels can get dangerously high. In type 2 diabetes, the pancreas usually makes some insulin but not enough.
• Ovaries. In women, these organs make estrogen and progesterone. These hormones help develop breasts at puberty, regulate the menstrual cycle, and support a pregnancy.
• Testes. In men, the testes make testosterone. It helps them grow facial and body hair at puberty. It also tells the penis to grow larger and plays a role in making sperm.

As you get older, it’s natural to notice some things related to your endocrine system. Your metabolism tends to slow down. So you might gain weight even though you haven’t changed how you eat or exercise. Hormonal shifts also explain, at least in part, why you’re more likely to have heart disease, osteoporosis, and type 2 diabetes as you age.

No matter how old you are, stress, infections, and being around certain chemicals can also mess with parts of your endocrine system. And genetics or lifestyle habits can increase your chances of an endocrine disorder like hypothyroidism, diabetes, or osteoporosis.

• Acromegaly. Sometimes the pituitary gland makes too much growth hormone and your bones get bigger. It usually affects your hands, feet, and face. It usually starts in middle age.
• Adrenal insufficiency. When you have this, your adrenal glands don’t make enough of certain hormones, like cortisol, which controls stress.
• Cushing’s disease. In this, your body makes too much cortisol. You could gain weight, get stretch marks, bruise easily at first, then get weakened muscles and bones and possibly develop a hump on your upper back.
• Hyperthyroidism. This is when your thyroid gland makes more hormones than your body needs. You might hear it called overactive thyroid. It makes your system run fast and you might feel nervous, lose weight, and have a rapid heartbeat or trouble sleeping.
• Hypothyroidism. When your body doesn’t make enough thyroid hormone, your system slows down. You might feel tired, gain weight, have a slow heartbeat, and get joint and muscle pains.
• Hypopituitarism. Sometimes your pituitary gland doesn’t make enough of certain hormones and your adrenal and thyroid glands can’t work right.
• Multiple endocrine neoplasia. This is a group of disorders that affect your endocrine system. It causes tumors on at least two endocrine glands or in other organs and tissues.
• Polycystic ovary syndrome. An imbalance of reproductive hormones can cause your ovaries to either not make an egg or not release it during ovulation. This can throw off your periods, cause acne, and make hair to grow on your face or chin.
• Precocious puberty. When glands that control reproduction don’t work properly, some kids start puberty abnormally early — around 8 in girls and 9 in boys.

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The Endocrine System and Glands of the Human Body: Function and Disorders

Written by Barbara Brody

• What Is the Endocrine System?
• What Is a Gland?
• Endocrine System Functions
• Parts of the Endocrine System
• Health Issues
• Endocrine System Disorders
• More

The endocrine system is a network of glands in your body that make the hormones that help cells talk to each other. They’re responsible for almost every cell, organ, and function in your body.

If your endocrine system isn’t healthy, you might have problems developing during puberty, getting pregnant, or managing stress. You also might gain weight easily, have weak bones, or lack energy because too much sugar stays in your blood instead of moving into your cells where it’s needed for energy.

A gland is an organ that makes and puts out hormones that do a specific job in your body. Endocrine and exocrine glands release the substances they make into your bloodstream.

Your endocrine system:

• Makes hormones that control your moods, growth and development, metabolism, organs, and reproduction
• Controls how your hormones are released
• Sends those hormones into your bloodstream so they can travel to other body parts

Many glands make up the endocrine system. The hypothalamus, pituitary gland, and pineal gland are in your brain. The thyroid and parathyroid glands are in your neck. The thymus is between your lungs, the adrenals are on top of your kidneys, and the pancreas is behind your stomach. Your ovaries (if you’re a woman) or testes (if you’re a man) are in your pelvic region.

• Hypothalamus. This organ connects your endocrine system with your nervous system. Its main job is to tell your pituitary gland to start or stop making hormones.
• Pituitary gland. This is your endocrine system’s master gland. It uses information it gets from your brain to tell other glands in your body what to do. It makes many important hormones, including growth hormone; prolactin, which helps breastfeeding moms make milk; antidiuretic hormone(ADH) (vasopressin), which controls blood pressure and helps control body water balance through its effect on the kidney, corticotropin /ACTH: Adrenocorticotrophic hormone. which stimulates the adrenal gland to make certain hormones, thyroid-stimulating hormone (TSH), which stimulates the production and secretion of thyroid hormones, oxytocin which helps in milk ejection during breast feeding; and luteinizing hormone, which manages estrogen in women and testosterone in men.
• Pineal gland. It makes a chemical called melatonin that helps your body get ready to go to sleep.
• Thyroid gland. This gland makes thyroid hormone, which controls your growth and metabolism. If this gland doesn’t make enough (a condition called hypothyroidism), everything happens more slowly. Your heart rate might slow down. You could get constipated. And you might gain weight. If it makes too much (hyperthyroidism), everything speeds up. Your heart might race. You could have diarrhea. And you might lose weight without trying. The thyroid gland also produces the hormone calcitonin, which may contribute to bone strength by helping calcium to be incorporated into bone.
• Parathyroid. This is a set of four small glands behind your thyroid. They play a role in bone health. The glands control your levels of calcium and phosphorus.
• Thymus. This gland makes white blood cells called T-lymphocytes that fight infection and are crucial as a child’s immune system develops. The thymus starts to shrink after puberty.
• Adrenals. Best known for making the “fight or flight” hormone adrenaline (also called epinephrine), these two glands also make hormones called corticosteroids. They affect your metabolism heart rate, oxygen intake, blood flow, and sexual function, among other things.
• Pancreas. This organ is part of both your digestive and endocrine systems. It makes digestive enzymes that break down food. It also makes the hormones insulin and glucagon. These ensure you have the right amount of sugar in your bloodstream and your cells.
• If you don’t make insulin, which is the case for people with type 1 diabetes, your blood sugar levels can get dangerously high. In type 2 diabetes, the pancreas usually makes some insulin but not enough.
• Ovaries. In women, these organs make estrogen and progesterone. These hormones help develop breasts at puberty, regulate the menstrual cycle, and support a pregnancy.
• Testes. In men, the testes make testosterone. It helps them grow facial and body hair at puberty. It also tells the penis to grow larger and plays a role in making sperm.

As you get older, it’s natural to notice some things related to your endocrine system. Your metabolism tends to slow down. So you might gain weight even though you haven’t changed how you eat or exercise. Hormonal shifts also explain, at least in part, why you’re more likely to have heart disease, osteoporosis, and type 2 diabetes as you age.

No matter how old you are, stress, infections, and being around certain chemicals can also mess with parts of your endocrine system. And genetics or lifestyle habits can increase your chances of an endocrine disorder like hypothyroidism, diabetes, or osteoporosis.

• Acromegaly. Sometimes the pituitary gland makes too much growth hormone and your bones get bigger. It usually affects your hands, feet, and face. It usually starts in middle age.
• Adrenal insufficiency. When you have this, your adrenal glands don’t make enough of certain hormones, like cortisol, which controls stress.
• Cushing’s disease. In this, your body makes too much cortisol. You could gain weight, get stretch marks, bruise easily at first, then get weakened muscles and bones and possibly develop a hump on your upper back.
• Hyperthyroidism. This is when your thyroid gland makes more hormones than your body needs. You might hear it called overactive thyroid. It makes your system run fast and you might feel nervous, lose weight, and have a rapid heartbeat or trouble sleeping.
• Hypothyroidism. When your body doesn’t make enough thyroid hormone, your system slows down. You might feel tired, gain weight, have a slow heartbeat, and get joint and muscle pains.
• Hypopituitarism. Sometimes your pituitary gland doesn’t make enough of certain hormones and your adrenal and thyroid glands can’t work right.
• Multiple endocrine neoplasia. This is a group of disorders that affect your endocrine system. It causes tumors on at least two endocrine glands or in other organs and tissues.
• Polycystic ovary syndrome. An imbalance of reproductive hormones can cause your ovaries to either not make an egg or not release it during ovulation. This can throw off your periods, cause acne, and make hair to grow on your face or chin.
• Precocious puberty. When glands that control reproduction don’t work properly, some kids start puberty abnormally early — around 8 in girls and 9 in boys.

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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 work 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 a vertical 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 IU / l, during ovulation from 2.7 to 6.7 IU / 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.
1.1 The importance of the endocrine system in the body 1.3 Interaction of the endocrine system with other body systems

1. 9 Influence of the endocrine system on the growth and development of the body