How does the endocrine system regulate bodily functions. What are the primary endocrine organs and their roles. Which hormones are produced by various glands and their effects on the body. How do the hypothalamus and pituitary gland interact in hormone production. What are the main pathologies associated with endocrine system disorders.

The Hypothalamus: The Bridge Between Nervous and Endocrine Systems

The hypothalamus plays a crucial role in connecting the nervous system to the endocrine system. This small but mighty structure in the brain receives and processes signals from various brain regions and pathways, translating them into hormones – the chemical messengers of the endocrine system.

Located in the head region, specifically within the brain, the hypothalamus is part of both the endocrine and nervous systems. Its primary function is to maintain homeostasis by regulating various bodily functions through hormone production and release.

Hypothalamic Functions and Associated Pathologies

• Temperature regulation
• Hunger and thirst control
• Sleep-wake cycles
• Emotional responses
• Sexual behavior and reproduction

The hypothalamus is susceptible to various pathologies, including:

• Alzheimer’s Disease
• Brain cancer
• Diabetes insipidus
• Epilepsy
• Parkinson’s Disease

These conditions can significantly impact the hypothalamus’s ability to regulate bodily functions, leading to a wide range of symptoms and complications.

The Pituitary Gland: The Master Regulator of Hormones

The pituitary gland, also known as the hypophysis or glandula pituitaria, is a small reddish-gray body measuring about 1 cm in diameter. Attached to the end of the infundibulum of the hypothalamus, this gland is responsible for secreting and storing hormones that manage various functions of the endocrine system.

Comprised of two main lobes – the anterior and posterior – the pituitary gland plays a pivotal role in hormone regulation. The anterior lobe, which makes up most of the pituitary’s mass, is responsible for secreting hormones. In contrast, the posterior lobe stores and secretes hormones produced by the hypothalamus.

Pituitary Gland Functions and Disorders

The pituitary gland’s primary functions include:

1. Growth regulation
2. Blood pressure control
3. Sex organ function
4. Thyroid gland regulation
5. Metabolism management

Disorders affecting the pituitary gland can lead to various pathologies, such as:

• Growth disorders
• Cushing’s syndrome
• Prolactinoma
• Acromegaly
• Hypopituitarism

Hormones of the Anterior Pituitary: Regulators of Bodily Functions

The anterior lobe of the pituitary gland produces and secretes several crucial hormones that regulate various bodily functions. These hormones are released in response to signals from the hypothalamus, which acts as a control center for hormone production.

Adrenocorticotropic Hormone (ACTH)

ACTH stimulates the adrenal glands to produce steroid hormones, primarily cortisol. These steroid hormones influence the metabolism of glucose, lipids, and proteins, providing cells with the energy needed to resist stress.

Follicle-Stimulating Hormone (FSH) and Luteinizing Hormone (LH)

FSH and LH target the gonads in both males and females, playing crucial roles in reproductive function:

• In females: FSH stimulates the ovaries to secrete estrogen and produce oocytes, while LH triggers ovulation.
• In males: FSH stimulates sperm development in the testes, and LH promotes testosterone production.

Human Growth Hormone (hGH)

hGH causes target cells to release insulin-like growth factors (IGFs), which promote cell growth and division, glucose release, and protein synthesis. This hormone is essential for normal growth and development, especially during childhood and adolescence.

Thyroid-Stimulating Hormone (TSH)

TSH stimulates the thyroid gland to release hormones that increase metabolism and promote nervous and skeletal system growth. This hormone is crucial for maintaining proper metabolic function throughout the body.

Posterior Pituitary Hormones: Regulators of Water Balance and Labor

The posterior lobe of the pituitary gland stores and releases two important hormones produced by the hypothalamus: Antidiuretic Hormone (ADH) and Oxytocin (OXT). These hormones play vital roles in regulating water balance and inducing labor during childbirth.

Antidiuretic Hormone (ADH)

ADH, also known as vasopressin, acts on the kidneys, blood vessels, and sweat glands in the skin to reduce water loss throughout the body. Its primary functions include:

• Increasing water reabsorption in the kidneys
• Constricting blood vessels to raise blood pressure
• Reducing sweat production

Oxytocin (OXT)

Oxytocin plays a crucial role in pregnancy, childbirth, and nurturing behaviors. Its main functions include:

• Causing smooth muscle contractions in the uterus to induce labor
• Stimulating milk ejection from the mammary glands
• Promoting bonding between mother and child

The Thyroid Gland: Regulator of Metabolism and Growth

The thyroid gland, located in the neck region, is a butterfly-shaped endocrine gland that plays a crucial role in regulating metabolism, growth, and development. It produces two main hormones: thyroxine (T4) and triiodothyronine (T3).

Thyroid Hormone Functions

Thyroid hormones have wide-ranging effects on the body, including:

• Regulating basal metabolic rate
• Influencing heart rate and cardiac output
• Affecting skeletal growth and bone maturation
• Modulating central nervous system development
• Regulating body temperature

Disorders of the thyroid gland can lead to conditions such as hypothyroidism (underactive thyroid) or hyperthyroidism (overactive thyroid), which can have significant impacts on overall health and well-being.

The Adrenal Glands: Stress Response and Homeostasis

The adrenal glands, located atop each kidney, are composed of two distinct parts: the adrenal cortex and the adrenal medulla. These glands play a crucial role in the body’s stress response and maintaining homeostasis.

Adrenal Cortex Hormones

The adrenal cortex produces several important steroid hormones:

1. Glucocorticoids (e.g., cortisol): Regulate metabolism and stress response
2. Mineralocorticoids (e.g., aldosterone): Control electrolyte balance and blood pressure
3. Androgens: Contribute to secondary sex characteristics

Adrenal Medulla Hormones

The adrenal medulla secretes catecholamines, primarily epinephrine (adrenaline) and norepinephrine (noradrenaline). These hormones are responsible for the “fight or flight” response, preparing the body for immediate action in stressful situations.

The Pancreas: Dual-Function Organ in Digestion and Glucose Regulation

The pancreas is a unique organ that serves both endocrine and exocrine functions. As an endocrine gland, it produces hormones that regulate blood glucose levels, while its exocrine function involves the production of digestive enzymes.

Endocrine Function: Islets of Langerhans

The endocrine portion of the pancreas consists of clusters of cells called islets of Langerhans. These islets produce several important hormones:

• Insulin: Lowers blood glucose levels by promoting glucose uptake and storage
• Glucagon: Raises blood glucose levels by stimulating glycogen breakdown and gluconeogenesis
• Somatostatin: Regulates the release of other pancreatic hormones
• Pancreatic polypeptide: Influences appetite and food intake

Disorders affecting the endocrine function of the pancreas can lead to conditions such as diabetes mellitus, characterized by impaired glucose regulation.

Exocrine Function: Digestive Enzyme Production

The exocrine portion of the pancreas produces digestive enzymes that are crucial for breaking down carbohydrates, proteins, and fats in the small intestine. These enzymes include:

• Amylase: Breaks down carbohydrates
• Lipase: Digests fats
• Trypsin and chymotrypsin: Break down proteins

Disorders affecting the exocrine function of the pancreas can lead to conditions such as pancreatitis or exocrine pancreatic insufficiency, which can significantly impact digestion and nutrient absorption.

The Gonads: Reproductive Hormone Production and Gamete Development

The gonads, which include the testes in males and ovaries in females, serve dual functions as both endocrine glands and reproductive organs. They are responsible for producing sex hormones and developing gametes (sperm or eggs).

Male Gonads: Testes

The testes produce several important hormones:

• Testosterone: The primary male sex hormone, responsible for the development of male secondary sex characteristics, muscle mass, and bone density
• Inhibin: Regulates FSH production by the pituitary gland
• Antimüllerian hormone (AMH): Plays a role in male fetal development

In addition to hormone production, the testes are responsible for spermatogenesis, the process of sperm production.

Female Gonads: Ovaries

The ovaries produce several hormones that regulate the menstrual cycle and female reproductive functions:

• Estrogen: Promotes the development of female secondary sex characteristics and regulates the menstrual cycle
• Progesterone: Prepares the uterus for potential pregnancy and maintains pregnancy if fertilization occurs
• Inhibin: Regulates FSH production by the pituitary gland

The ovaries also contain follicles that house and nurture developing oocytes (eggs) until ovulation.

Disorders affecting the gonads can lead to various reproductive and hormonal issues, including infertility, hormonal imbalances, and developmental abnormalities.

The Pineal Gland: Regulator of Circadian Rhythms

The pineal gland, a small endocrine gland located in the brain, plays a crucial role in regulating circadian rhythms and sleep-wake cycles. Its primary function is the production and secretion of melatonin, a hormone that helps regulate the body’s internal clock.

Melatonin Production and Function

Melatonin production is influenced by light exposure, with levels typically increasing in the evening and decreasing in the morning. This hormone has several important functions:

• Regulating sleep-wake cycles
• Influencing reproductive cycles in seasonal breeding animals
• Acting as an antioxidant
• Potentially modulating immune function

Disorders affecting the pineal gland or melatonin production can lead to sleep disturbances, circadian rhythm disorders, and potentially impact mood and cognitive function.

The Thymus: Crucial for Immune System Development

The thymus, located in the upper chest behind the breastbone, is an endocrine gland that plays a vital role in the development of the immune system, particularly during childhood and adolescence. Although it begins to shrink and become less active after puberty, its early influence on immune function is crucial.

Thymus Functions

The primary functions of the thymus include:

• Production and maturation of T-lymphocytes (T-cells)
• Secretion of thymosin, a hormone that stimulates T-cell production and differentiation
• Development of self-tolerance in the immune system

Disorders affecting the thymus can lead to immune deficiencies, autoimmune diseases, or increased susceptibility to infections.

Understanding the complex interplay between various endocrine glands and their hormones is crucial for comprehending how the body maintains homeostasis and responds to internal and external stimuli. From regulating metabolism and growth to controlling reproductive functions and stress responses, the endocrine system plays a vital role in nearly every aspect of human physiology. By continuing to study and unravel the intricacies of this system, researchers and healthcare professionals can develop better strategies for diagnosing and treating endocrine disorders, ultimately improving patient outcomes and quality of life.

Glossary of the Endocrine System

Primary endocrine organs secrete hormones that chemically regulate body functions.

System: Endocrine

Region: Head, Neck, Abdomen

Hypothalamus

The hypothalamus connects the nervous system to the endocrine system. See it in 3D!

System: Endocrine, Nervous

Region: Head (Brain)

Function: It receives and processes signals from other brain regions and pathways and translates them into hormones, the chemical messengers of the endocrine system.

Pathologies: Alzheimer’s Disease, amyotropic lateral sclerosis, aphasia, arteriovenous malformations, brain aneurysm, brain cancer, cerebral palsy, Chiari malformation, coma, concussion, Creutzfeldt-Jakob Disease, delirium, dementia, diabetes insipidus, encephalitis, epilepsy, fainting, Huntington’s Disease, hydrocephalus, Lewy body disease, migraine, mild cognitive impairment, neuroblastoma, Parkinson’s Disease, progressive supranuclear palsy, seizures, stroke, Tourette Syndrome, transient ischemic attack, traumatic brain injury

Hypophysis, glandula pituitaria

The pituitary gland (r, l), a small reddish-gray body about 1 cm in diameter, secretes and stores hormones that manage functions of the endocrine system. Attached to the end of the infundibulum of the hypothalamus, the pituitary consists of an anterior lobe and a posterior lobe. See it in 3D!

System: Endocrine

Region: Head (Brain)

Function: The anterior lobe secretes hormones and comprises most of the pituitary’s mass. The posterior pituitary stores and secretes hormones produced by the hypothalamus.

Pathologies: Alzheimer’s Disease, amyotrophic lateral sclerosis, aphasia, arteriovenous malformations, brain aneurysm, brain cancer, cerebral palsy, Chiari malformation, coma, concussion, Creutzfeldt-Jakob Disease, delirium, dementia, diabetes insipidus, encephalitis, epilepsy, fainting, growth disorders, Huntington’s Disease, hydrocephalus, Lewy body disease, migraine, mild cognitive impairment, neuroblastoma, Parkinson’s Disease, progressive supranuclear palsy, seizures, stroke, Tourette Syndrome, transient ischemic attack, traumatic brain injury

Hormones sent from the hypothalamus to the anterior lobe of the pituitary gland function as signals. They stimulate or inhibit the release of anterior pituitary hormones, which regulate endocrine glands and control a range of body functions.

System: Endocrine

Function: Anterior pituitary hormones stimulate growth and control glands throughout the body.

Adrenocorticotropic hormone (ACTH) causes the adrenal glands to produce steroid hormones. These steroid hormones influence the metabolism of glucose, lipids, and proteins, which gives cells energy to resist stress.

System: Endocrine

Source: Anterior pituitary

Target Organ: Adrenal glands

Follicle-stimulating hormone (FSH) targets the gonads in both males and females. In females, it stimulates the ovaries to secrete estrogen and produce oocytes. In males, it stimulates sperm development in the testes.

System: Endocrine

Source: Anterior pituitary

Target Organs: Testes, ovaries

Luteinizing hormone (LH) targets the gonads in both males and females. In males, it stimulates the production of testosterone by the testes. In females, it stimulates ovulation.

System: Endocrine

Source: Anterior pituitary

Target Organs: Testes, ovaries

Human growth hormone (hGH) causes target cells to release insulin-like growth factors (IGFs), which are hormones that promote cell growth and division, glucose release, and protein synthesis.

System: Endocrine

Source: Anterior pituitary

Target Organs: Skeletal muscles, bones, liver

Melanocyte-stimulating hormone (MSH) causes melanocytes in the skin to produce more melanin (pigment).

System: Endocrine

Source: Anterior pituitary (pars intermedialis)

Target Organs: Skin

Prolactin (PRL) induces milk production in mammary glands.

System: Endocrine

Source: Anterior pituitary

Target Organs: Mammary glands

Thyroid-stimulating hormone (TSH) causes the thyroid gland to release hormones that increase metabolism and promote nervous and skeletal system growth.

System: Endocrine

Source: Anterior pituitary

Target Organs: Thyroid gland

The hormones ADH and OXT are produced in the hypothalamus and are stored in the posterior pituitary, from which they are released into circulation.

System: Endocrine

Function: Posterior pituitary hormones regulate water levels and induce labor.

ADH acts on the kidneys, blood vessels, and sweat glands in the skin to reduce water loss throughout the body.

System: Endocrine

Source: Posterior pituitary

Target Organs: Kidneys, blood vessels, sweat glands

OXT factors into pregnancy and nurturing. It causes smooth muscle contractions of the uterus to induce birth. Later it stimulates milk ejection from the mammary glands and promotes bonding between mother and child.

System: Endocrine

Source: Posterior pituitary

Target Organs: Uterus, mammary glands

The system of vasculature that connects the hypothalamus and the anterior pituitary is called the hypophyseal portal system.

System: Circulatory

Region: Head (Brain)

Function: Capillaries from the superior hypophyseal artery surround the hypophysis and collect hypothalamic hormones that are carried to the anterior lobe of the pituitary via the portal system, where they stimulate or inhibit the release of pituitary hormones.

Pathologies: Arteriovenous malformations, diabetes type 1, diabetes type 2

Epiphysis cerebri

The pineal gland is small and pinecone-shaped, located at the posterior of the diencephalon region in the brain. See it in 3D!

System: Endocrine, Nervous

Region: Head (Brain)

Function: The pineal gland secretes melatonin at various levels throughout the day and night; these secretions are thought to contribute to cycles of wake and sleep (circadian cycle).

Pathologies: Alzheimer’s Disease, amyotrophic lateral sclerosis, aphasia, arteriovenous malformations, brain aneurysm, brain cancer, cerebral palsy, Chiari malformation, coma, concussion, Creutzfeldt-Jakob Disease, delirium, dementia, encephalitis, epilepsy, fainting, Huntington’s Disease, hydrocephalus, Lewy body disease, migraine, mild cognitive impairment, neuroblastoma, Parkinson’s Disease, progressive supranuclear palsy, seizures, stroke, Tourette Syndrome, transient ischemic attack, traumatic brain injury

Glandula thyroidea

The thyroid gland sits in the throat region, just below the larynx, served by large arteries with many branches and a dense network of capillaries.

System: Endocrine

Region: Neck

Function: The thyroid gland releases thyroid hormone, in the form of thyroxine (T4) and triiodothyronine (T3), which increase metabolism, glucose use, protein synthesis, and nervous system development. It also releases calcitonin (CT), which promotes calcification of bones. See it in 3D!

Pathologies: Hyperthyroidism, hypothyroidism

Glandula parathyroidea superior, glandula parathyroidea inferior

The parathyroid glands are small, brownish-red structures located between the posterior borders of the lateral lobes of the thyroid gland. Normally, there are four parathyroids: two superior (upper) parathyroid glands (r, l) and two inferior (lower) parathyroid glands (r, l).

System: Endocrine

Region: Neck

Function: They secrete parathyroid hormone (PTH or parathormone), which stimulates bones to release calcium into the blood when blood (calcium) levels are low. PTH also causes the kidneys to reduce calcium secretion into urine to further elevate calcium levels in the blood.

Pancreas

The pancreas is located between the stomach and small intestine. In addition to its digestive functions, it is a gland that secretes hormones necessary to regulate blood glucose levels. See it in 3D!

System: Endocrine, Digestive

Region: Abdomen

Function: When blood sugar is low, alpha cells in the islets release glucagon. Glucagon spurs the liver to break down glycogen and release more glucose into the blood. When blood sugar is high, beta cells in the islets release insulin, which increases glucose reuptake.

Pathologies: Pancreatitis, prediabetes

Glandula suprarenalis

The adrenal glands are located superior to the kidneys on either side of the vertebral column. Each adrenal gland consists of an outer cortex and an inner medulla.

System: Endocrine

Region: Abdomen

Function: The adrenal cortex produces three types of steroids. Glucocorticoids, such as cortisol, manage protein and glucose levels. Mineralocorticoids, such as aldosterone, manage the levels of water and salt. Gonadocorticoids are androgens, which can be converted to estradiols. The adrenal medulla produces epinephrine (E) and norepinephrine (NE), which promote the fight-or-flight responses of the sympathetic nervous system during stress.

Pathologies: Pheochromocytoma

Secondary endocrine organs include the gonads, kidneys, and thymus.

System: Endocrine

Region: Thorax, abdomen

Function: Secondary endocrine organs secrete hormones as a secondary function.

Stress stimulates the adrenal glands to produce hormones that ramp up body activity in the fight-or-flight response. The hypothalamus commands the adrenal glands directly (via nervous signals) to ramp up production of epinephrine and norepinephrine. These hormones promote the “fight-or-flight” response: breathing and heart rate increase and our muscles get a burst of energy. As stress continues into the resistance phase, the pancreas and adrenal glands produce glucagon and steroids that elevate blood glucose to provide more energy.

System: Endocrine

Endocrine system 1: overview of the endocrine system and hormones

26 April, 2021

The endocrine system comprises glands and tissues that produce hormones for regulating and coordinating vital bodily functions. This article, the first in an eight-part series, is an overview of the system

Abstract

The endocrine system is made up of glands and tissues that produce and secrete hormones to regulate and coordinate vital bodily functions. This article – the first in an eight-part series on the anatomy and physiology of the endocrine system – explores the nature of endocrine glands and tissues, and the role of hormones as chemical signals that are carried in the blood. It also highlights the varying roles of hormones in regulating and coordinating physiological processes, as well as maintaining homoeostasis in the body.

Citation: Knight J (2021) Endocrine system I: overview of the endocrine system and hormones. Nursing Times [online]; 117: 5, 38-42.

Author: John Knight is associate professor in biomedical science, College of Human and Health Sciences, Swansea University.

This article has been double-blind peer reviewed

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Human endocrine glands (endocrine glands)

Endocrine glands, or endocrine glands , produce hormones that enter directly into the blood or lymph.

Hormones are compounds belonging to the group of biologically active substances. Hormones act on “target” cells, as a result, biochemical processes in these cells change. Hormones are able to act when they are in the blood in very small quantities, so the endocrine glands are small organs.

Regulation of the body’s work by means of hormones is called humoral regulation . In addition, the work of the human body is regulated by the nervous system (nervous regulation).

The work of the endocrine glands themselves is regulated by both the nervous and humoral systems. In the latter case, some glands produce hormones that affect the production of hormones by other endocrine glands.

Endocrine glands may include:

1. Hypothalamus
2. Pituitary
3. Epiphysis
4. Thyroid
5. Parathyroid glands
6. Adrenals
7. Thymus, or thymus gland
8. Pancreas
9. Ovaries (for women)
10. Testicles, or testicles (in men)

The last three of the above are glands of mixed secretion. In addition to hormones, they secrete substances or cells that do not enter the bloodstream and are not hormones. This is how the pancreas secretes digestive enzymes into the duodenum. And the gonads produce eggs or sperm.

The hypothalamus is part of the diencephalon. In addition to neurons of the usual type, it contains neurosecretory cells that produce substances of a protein nature that stimulate or inhibit the production of pituitary hormones.

Neurosecretory cells convert nerve impulses into neurohormonal ones. These cells respond to impulses coming to them like ordinary nerve cells, but when excited, they also release substances that affect the pituitary gland, and it, in turn, changes the state of other endocrine glands.

Thus, through the hypothalamic-pituitary system, the nervous system can enhance or inhibit the secretory activity of the endocrine glands. Also, the hypothalamus is able to “evaluate” the concentration of hormones in the blood and, depending on this, transmit signals through the nervous system and stimulate the production of its own hormones and the pituitary gland.

The pituitary gland is located directly below the hypothalamus and is connected to it by a funnel and a stalk, through which the neurosecretion enters. The pituitary gland responds to chemicals from the hypothalamus and secretes its own hormones.

The pituitary gland is located in the “Turkish saddle” – a special deepening of the bones of the cranial cavity.

Growth hormone, somatotropin, is produced in the anterior pituitary gland. It enhances protein synthesis, growth and division of target cells.

Tropic hormones are also produced in the anterior lobe (they regulate the activity of other endocrine glands):

• thyroid stimulating hormone (TSH) regulates the thyroid gland,
• gonadotropic hormone acts on the gonads,
• adrenocorticotropic hormone (ACTH) regulates the adrenal cortex.

The secretion of pituitary hormones into the blood is regulated by the feedback principle. A decrease in the content of a certain hormone in the blood causes the release of the corresponding hormone by the pituitary gland, which increases the activity of the gland.

The posterior pituitary secretes vasopressin into the blood, which enhances the reabsorption of water from primary urine. Also from here comes the release of oxytocin, due to which the contraction of smooth muscles increases.

Melanocyte-stimulating hormone (MSH) is produced in the intermediate pituitary gland.

Pineal gland refers to the brain, regulates the biological rhythms of the body (daily, seasonal and others), produces substances that affect the color of the skin.

At an early age, the pineal gland affects all the glands involved in the processes of growth and development of the body.

Thymus located behind the sternum. Its hormones affect the immune system, regulate the function of other endocrine glands: inhibit the activity of the thyroid gland, delay the puberty of the body.

The thyroid gland is located on the anterior wall of the larynx and produces the hormone thyroxine, which contains iodine. Thyroxine increases the intensity of metabolism, stimulating cellular respiration and increasing the production of heat by the body (thermogenesis).

The formation and secretion of thyroid hormones is influenced by the content of iodine in the blood and the pituitary hormone. With a decrease in iodine in the blood, the release of thyroid-stimulating hormone by the pituitary gland, which stimulates the function of the thyroid gland, increases.

The parathyroid glands are two pairs of small glands located on the posterior surface of the thyroid gland. Parathyroid hormone is secreted, which regulates the level of calcium and phosphorus in the blood, affects the excitability of the nervous and muscular systems. The regulation of mineral metabolism in the bones is associated with this hormone.

The production of parathyroid hormone depends on the presence of vitamin D in the blood.

With an increase in the function of the parathyroid glands, calcium passes from the bones into the blood, the bones become soft. At the same time, they are deformed and bent.

With a decrease in the function of the parathyroid glands, the calcium content in the blood decreases, which leads to an increase in the excitability of the nervous system and muscles, muscle cramps occur.

The pancreas secretes the hormone insulin. The continuous release of insulin into the blood is necessary so that glucose, which serves as the main source of energy, can pass from the blood plasma into tissues, and its excess is deposited in the liver in the form of glycogen.

In a smaller amount, the pancreas secretes another hormone – glucagon. It has the opposite effect of insulin – it raises blood sugar levels.

Adrenal glands are located at the upper poles of the kidneys and consist of two layers: outer cortical and inner medulla.

The adrenal cortex produces more than 40 hormones that affect metabolism, regulate mineral and water metabolism.

The adrenal medulla produces the hormone adrenaline. Its secretion sharply increases under the action of strong stress stimuli on the body. Adrenaline increases the excitability of the nervous system, increases and speeds up heart contractions, respiration, muscle contractions, stimulates blood circulation, and reduces muscle fatigue.

The adrenal glands also produce a number of sex hormones.

The secretion of hormones of the adrenal cortex is regulated by the hormone of the pituitary gland and the nervous system.

Ovaries produce groups of estrogens and progestins.

Estrogens include the hormone estradiol, which is responsible for the maturation of eggs, during puberty is involved in the formation of female secondary sexual characteristics.

Progestins include progesterone, which inhibits the maturation of new eggs during pregnancy. Progesterone also prepares the uterus for the introduction of a fertilized egg, promotes the growth and development of the fetus.

Testicles secrete testosterone and other androgen hormones. Testosterone ensures the constancy of sperm production, in the process of body development it is necessary for the formation of the reproductive system according to the male type and the development of male secondary sexual characteristics.

Functional anatomy of the endocrine glands – online presentation

1. Lecture No. 10 Functional anatomy of the endocrine glands

1

2. Endocrinology

the science of the internal glands
secretions (endocrine
glands) their development,
structure, function,
mechanisms of action
specific products of their vital activity –
hormones, as well as about
diseases caused by
dysfunction of these glands and
changes in the action of hormones.
2

3. Stages of development of endocrinology

I. Since 1849, when the German physiologist
Adolf Bertol pointed out that during
castration of cocks and subsequent transplantation into the abdominal cavity

testicles from another cock, all
effects of castration disappear, i. e.
proved that there are organs that affect
metabolism.
3
II. Since 1902, when the British
Ernest Starling and William
Bayliss discovered secretin,
which
stimulated the secretion of pancreas. This gave
an impetus to the detection of hormones
(from the Greek hormao – I excite).
4
III. Since 1921, when the Australian
pharmacologist Otto Levi discovered the
hormonal substance

–
guitar picks. Then
adrenergic
and
cholinergic neurons were described, and the last

peptidergic neurons were described.
The concept
about
“neuroendocrine regulation” has arisen.
5
IV. Since 1968, when the Englishman Everson
Pierce discovered cells that produce
peptide hormones (apudocytes or
APUD cells).
They are
available
in almost all organs, including
in the organs of the immune system.
These cells provide instant
deployment
protective
forces
organism
for
autoregulation
immune cell activity.
6

7. General features of the structure of the endocrine glands

1. Absence of excretory ducts,
hormones are released into the internal environment
of the body (into the blood and lymph)
2. They have a rich blood supply.
3. Features of the structure of the capillary network inside the
organ: the endothelium of the sinusoidal capillaries
directly adjacent to the epithelial
cells or epithelial cells protrude
directly into the lumen of the vessels.
4. They have a small value (relative to their
value for the body)
5. A high degree of specificity of the action of
hormones on target organs
6. The closest functional connection with the nervous system

8. Properties of hormones

1. Maximum biological activity
2. Strict specificity of action
3. The hormone can pass through
cell structures, cell membranes and
affect the enzyme systems of
cells.
4. Hormones have a daily rhythm
5. Each hormone has a certain half-life

6. Inactivation of hormones occurs in the
8
liver and kidneys

9. Functions of hormones

1. Provide
physical,
sexual and mental development of
people
2. Provide physiological adaptation of the body

3. Participate
in maintaining
homeostasis
9

10. ENDOCRINE SYSTEM

The endocrine system includes
glands that have specialized in the process of evolution
and individual groups of cells
that produce
the highest degree
biologically active substances – hormones.
10

11. Classification of endocrine glands

I. According to the principle of embryogenesis
according to A.A. Zavarzin and S.I. Shchelkunov, 1954
and gills
pockets – branchiogenic group (branchia
– gill): thyroid, parathyroid
and thymus.
11
2. Glands of ENTODERMAL
origin, developing from the
epithelium of the trunk intestine – the endocrine
part of the pancreas (islets
of Langerhans).
3. Glands of MESODERMAL
origin – cortical substance
of the adrenal glands and interstitial
cells of the gonads.
12
4. Glands of ECTODERMAL origin
– neurogenic group,
neural tube derivatives: pituitary and
epiphysis
5. Glands of ECTODERMAL
origin, derivatives
of the sympathetic nervous system,
adrenal medulla and
paraganglia (chromaffin bodies).
13
II. According to the principle of structural organization and functional interdependence

1. Central – hypothalamic-pituitary system:
1) Hypothalamus (neurosecretory nuclei)
2) Pituitary gland
3) Pineal gland
2. Peripheral:
1) Dependent on the anterior lobe of the pituitary gland:
a) thyroid gland (thyrocytes)
b) adrenal cortex
c) gonads (testicles, ovaries)
d) placenta
b) Parathyroid glands
c) Adrenal medulla
d) Islets of Langerhans of the pancreas
e) Single hormone-producing cells of nervous and
other origin
14

15.

Thyroid gland, Glandula thyroidea

15
1. Topography
In front of the larynx and trachea, level CIV-CVII
lower pole of the lobes – at the level of 5-6 cartilages of the trachea
2. Weight
On average in an adult – 16-18.5 g (max m = 25 – 30 g )
3. Structure
1. Two lobes – right and left – are connected
by an isthmus, located at the level of 2-3 cartilage
of the trachea
2. Outside – a fibrous capsule, from which
trabeculae extend, dividing it into lobules
3. Lobes consist of follicles
4. Hormones
1. Thyroxine
2. Triiodothyronine
3. Calcitonin (C-cells)
5. Action
of hormones
1. Regulate basic gas and protein metabolism
2. Stimulate mental development
3. Stimulate osteoblast activity
6. Hypofunction
1. Cretinism
3 Myxedema
2 Juvenile hypothyroidism
4. Hypothyroidism in adults
7. Hyperfunction Graves’ disease, or endemic goiter
16
• Hyperthyroidism –
Graves’ disease
:
1.
2.
3.
4.
goiter
bulge
tremor
tachycardia
17
• Hypothyroidism:
1. Cretinism – before birth
or at an early age
2. Juvenile hypothyroidism – in
older children –
there is a delay in sexual development

3. Hypothyroidism in adults with
moderate deficiency

4. Myxedema – pronounced
hypothyroidism in adults –
characterized by
dwarfism and mental underdevelopment

18

19. PARATHYROID GLANDS, Glandula parathyroidea

19
1. Topography
Paired upper and lower bodies,
located on the
posterior surface of the thyroid lobes

2. Weight
Average total weight – 1.18 g
3. Hormones
Parathyroidin (parathormone) 90 135 4. Action
hormones
1. Regulate the exchange of Ca and P in the blood.
2. Stimulate osteoclasts
5. Hypofunction
Tetany
6. Hyperfunction
1. Osteoporosis
2. Recklinghaus disease
20

HYPERPARATHYROISIS
1. deformity skeleton: bones
soften, multiple fractures
, spine
shorten, skull
increase
2. hypercalcemia: calcium
is deposited in organs and vessels
HYPOPARATHYROISIS
1. painful tonic spasms
2. removal of glands leads to death from
seizures
21

22. PANCREAS, Pancreas

endocrine function is performed
ISLANDS OF LANGERHANS
22
1. Topography
In the parenchyma of the pancreas
2. Weight
3. Structure
m islets no more than 1/100 m of the gland – 0.65-0.8 g
4. Hormones
α-cells – glucagon
β-cells – insulin
glucagon :
5. Action
hormones
groups of epithelial cells forming islets
(up to 320)
1) accelerates the breakdown of glycogen
2) promotes an increase in blood glucose

insulin:
cell, reducing the content of
blood glucose
2) affects the metabolism of proteins and fats
6. Hypofunction
Diabetes mellitus
7. Hyperfunction Rare phenomenon
23

predisposition
symptoms :
1) polyuria – frequent urination,
2) polydipsia – intense thirst,
3) polyphagia – voracity
4) in advanced cases –
trophic disorders, up to
gangrene (diabetic foot),
5) damage to the kidneys, eyes, heart,
skeletal muscles and nervous system.
24

25. ADRENAL, Glandula suprarenalis

25
cortex and medulla
• in the cortex three zones:
1. glomerular (zona glomerulosa),
2. fascicular (zona fasciculata),
3. reticular (zona reticularis)
4. Hormones
cortical 1. glomerular zone – mineralocorticoids
substance fascicular zone – glucocorticoids
2.
3.
reticular zone – sex hormones
cerebral 1. adrenaline
substance 2. norepinephrine
5. Action
hormones 901 35 cortical 1. metabolic processes
substance 2. puberty
medulla
substance
Hypofunction
Adrenaline: dilates all blood vessels, except
skin ones, enhances the work of the heart, increases blood pressure.
Norepinephrine: dilates skin vessels, increases blood pressure
primary insufficiency of the cortex – bronze disease
Hyperfunction of the cortex – hirsutism, feminism
medulla – hyperglycemia, glucosuria
26

27. Hypofunction of the adrenal cortex – bronze disease, Addison’s disease 1. bronze or black skin 2. weight loss 3.

Hyperfunction of the adrenal cortex
Excessive synthesis of androgens
leads to incorrect
formation of the genital organs:
1. In people with a female genotype, the development of
according to the male type is hirsutism.
2. People with the male genotype –
have precocious puberty, but
lack spermatogenesis – feminism.
Adrenal cortex hypofunction –
bronze disease, Addison’s disease
1. bronze or black skin
2. weight loss
3. gastrointestinal disorders
27
medulla hypofunction –
not observed
medulla hyperfunction – 90 135 Pheochromocytoma
Symptoms attack (effect of administration of large doses of
adrenaline and norepinephrine):
1. feeling of fear
2. deathly pallor
3. shock with profuse sweating
4. hypertension
28

physeal fossa of the Turkish saddle of the body of the sphenoid bone

2. Weight
m ♂ – 0.5 g
3. Structure
1. anterior lobe – adrenohypophysis
2. posterior lobe – neurohypophysis
3. intermediate lobe
4.
Hormones
and their action

m ♀ – 0, 6 g
front
share
1. somatotropic (GH) – growth hormone
2. thyrotropic (TSH) – stimulates the secretion of thyroxin
3. adrenocorticotropic (ACTH) – stimulates the secretion of
hormones of the adrenal cortex
4. follicle stimulating (FSH) –
y ♂ – regulates spermatogenesis
y ♀ – development of follicles in the ovary, estrogen secretion
5. luteinizing (LH) –
y ♂ – production of testosterone
y ♀ – affects ovulation, maturation of the corpus luteum
6. lactotropic (LTH) – stimulates milk lactation
glands and progesterone secretion
posterior lobe

1. vasopressin – antidiuretic effect
2. oxytocin – stimulates uterine contractions, lactation
30
intermediate
1. melanocyte stimulating (MSH) – affects
• HYPERFUNCTION CIA
anterior lobe –
GH hyperproduction
1) Gigantism – at a young age
–
uneven growth
up to 250 cm and more
2) Acromegaly – in
adults (an increase in
terminal parts of the body –
arms, legs, nose,
jaws)
31

32. HYPOFUNCTION

1. anterior pituitary – insufficiency
STG
1) Dwarfism –
• The body has normal proportions and
is symmetrical
• The development of bones, teeth and puberty 90 135 inhibited
• Mental development – Normal
2. The posterior pituitary gland – insufficiency
vasopressin
1) non -sha shagal diabetes
32

33. Shine body, epiphyse, corpus pineale (epiphysis cerebri)

33
1. Topography 9 topography 9 topography
in the groove between the superior colliculi
quadrigemina
2. Weight
4. Hormones
m – 0.1-0.2 g
1. melatonin
2. hormone that inhibits the gonadotropic
pituitary function – antigonadotropin
3 serotonin
5. Action
hormones
maximum activity from 2 to 8 years
1. regulation of biorhythms
2. regulation of pigment metabolism
3. inhibitory effect on sexual development and
carbohydrate metabolism
6. Hypofunction
Early puberty
7. Hyperfunction
Violation of puberty
34

35. GENERAL GLANDS: ♂-testis, Testis; ♀-ovary, Ovarium

1. Topography ♂ In the scrotum
♀ In the pelvic cavity
2. Weight
♂ 20–30 g
♀ 5–8 g
3. Structure
♂ Leydig interstitial cells 90 135 ♀ granular layer of maturing follicles
4 Hormones
♂ Testosterone
♀ 1. Estradiol (produced by the follicle)
2. Progesterone (produced by the corpus luteum
, placenta and follicle before
35
ovulation
5. Action
hormones
♂ 1.