One of the most important sections of anatomy for understanding the structure of the human body is the study of the hormonal system. In order to understand this complex and multi-level structure, it is better to refer to the schematic table of the endocrine glands, their hormones and functions. With its help, you can understand this issue in more detail.
What are glands in general and what are endocrine glands?
Gland is an organ in the human or animal body that produces and secretes certain biologically active substances that are necessary to maintain vital functions. These substances are called secrets. They can be secreted into the internal channels of the human body - into the blood, lymph - or out. According to this criterion, the glands are divided into organs of internal, external and mixed secretion. Endocrine glands belong to the organs of internal secretion: they do not have exit ducts. In general, they make up the endocrine system. The table "Glands and hormones" shows this more clearly.
Endocrine system
It is a functional relationship between tissues, cells and endocrine glands that secrete secretions (hormones) into the bloodstream, lymph flow, and intercellular fluid, and thus conduct hormonal regulation. It traditionally distinguishes three sections:
- A system of endocrine glands that does not have additional tasks. The result of its production are hormones.
- The system of glands of mixed secretion, which performs other functions besides the endocrine one. It includes the thymus, pancreas and gonads.
- A system of glandular cells that secrete hormone-like substances. The hormones produced by these organs enter directly into the circulatory system, lymph, or tissue fluid.
The functions of the endocrine glands and their hormones
The table below describes the multiple tasks of this system. The main thing is that it produces hormones that exercise control and are responsible for the normal course of the body’s vital processes. Thus, firstly, the endocrine system performs the function of chemical regulation, coordinates the work of all organs, is responsible for hematopoiesis, metabolism, etc. Secondly, it maintains the balance of the internal environment of the body, helps it adapt to the effects of the external environment. Thirdly, along with other systems, it is involved in regulating the growth and development of the body, its sexual identification and reproduction, as well as in energy-generating and energy-saving processes. The mental activity of the body is also very dependent on the endocrine system of glands and hormones (functions in the table).
Pituitary
This gland is very small in size, but of great importance for the normal functioning of all organs. The pituitary gland is located in the fossa of the sphenoid bone of the skull, is connected with the hypothalamus and is divided into three lobes: anterior (adenohypophysis), intermediate and posterior (neurohypophysis). In the adenohypophysis, all the main hormones are produced: somatotropic, thyrotropic, adrenocorticotropic, lactotropic, luteinizing, follicle-stimulating - they control the excretory activity of peripheral endocrine glands. The role of the neurohypophysis, that is, the posterior lobe, is that hormones produced by the hypothalamus move into it along the pituitary pedicle: vasopressin, which is involved in the regulation of water content in the body, increasing the degree of reverse absorption of fluid in the kidneys, and oxytocin, by which smooth muscle contraction.
Thyroid
The thyroid gland is a very important, producing iodine-containing hormones endocrine gland. The function of the hormones (table below) of this gland includes the promotion of metabolism, the growth of cells and the whole organism as a whole. Its main hormones are thyroxine and triiodothyronine. There is a third hormone secreted by the thyroid gland - calcitonin, which is responsible for the concentration of calcium and phosphates in the body and prevents the formation of cells that destroy bone tissue. It also activates the reproduction of young bone cells. They participate in the regulation of mitochondria, where oxidation processes occur with the release of energy-saturated molecules. Due to the insufficient production of these hormones, energy metabolism suffers: the heart begins to contract less and less, resulting in swelling. Lack of iodine causes a thickening of the thyroid tissue, resulting in goiter formation. In order to prevent thyroid diseases, potassium iodide is often included in table salt. With the excessive work of this organ, excess energy is produced: the activity of the heart is strengthened, pressure is increased, oxidative reactions are accelerated, a person is losing weight. This can lead to serious illness.
Parathyroid glands
The anatomy of the endocrine glands and their hormones (table below) also includes four parathyroid glands, they are oval and located in the tissues between the thyroid gland and the esophagus. The main hormone they produce is parathyrin (parathyroid hormone). Its main function is to regulate the level of ions in the blood. If it rises, the calcium level also increases, while the phosphate content remains unchanged. Excessive secretion of parathyroid hormone can provoke degradation and demineralization of bone tissue, which is fraught with bone fractures and muscle weakness. Insufficient secretion of this hormone causes a sharp increase in muscle and nervous excitability, up to the development of convulsive attacks.
Pancreas
This large secretory organ is located between the duodenum and spleen. The intracretory pancreas is called the islets of Langerhans. They are different types of cells that produce polypeptide hormones: glucagon, which stimulates the breakdown of glycogen carbohydrate in the liver, thereby increasing blood glucose and maintaining it at a constant level. Insulin, which regulates the metabolic processes of proteins, fats and carbohydrates, lowers blood glucose levels. Somatostatin, suppressing the synthesis of growth hormone, insulin and glucagon, pancreatic polypeptide that stimulates the production of gastric juice and inhibits the secretion of the pancreas. Ghrelin, which increases appetite. Impaired secretion of glucagon and insulin can lead to diabetes.
Adrenal glands
These are small glands in the shape of pyramids located on the top of the kidneys. The table of hormones of the endocrine glands indicates that this body produces hormones in its two departments - the cerebral and cortical. In the cortical division, which is divided into three zones, corticosteroids are produced. Mineralocorticoid hormones are produced in the first zone (glomerular), which control the mineral and ion exchange in cells and maintain their electrolyte balance. In the second, bundled - glucocorticoids that monitor the exchange of proteins, fats and carbohydrates, and in the third, mesh zone - sex hormones (androgens).
The brain section of the adrenal glands transports catecholamines into the blood: norepinephrine and adrenaline. Norepinephrine controls the nervous processes in the sympathetic zone. Catecholamines are involved in the regulation of fat and carbohydrate metabolism, promote adaptation to stress, releasing adrenaline in response to emotional irritations.
Thymus
The thymus gland, or thymus, is a small organ located behind the sternum, above the clavicle. It controls the functioning of the immune system throughout the course of human life. However, the thymus gland decreases with age and becomes weaker - from childhood to puberty, its function is maximally active, and then it gradually decreases. This gland produces several hormones: thymalin, thymosin, insulin-like growth factor, thymic humoral factor. Thymus is responsible for immunity, participates in the regulation of energy and lymph flow metabolism, and also produces and activates T-lymphocytes, which are necessary to provide antitumor and antiviral protection. If the functionality of the thymus is reduced, immunity is also reduced.
Pineal gland
The pineal gland (pineal gland) is located in the middle of the brain, between the hemispheres, next to the hypothalamus. Its main function is the regulation of human daily biorhythms. The pineal gland secretes the hormones melatonin and serotonin. Melatonin has a calming, relaxing effect, prepares the body for sleep. In addition, it alleviates stress and strengthens the immune system. Serotonin is a raw material for the production of melatonin. During the day, it enters the bloodstream and acts in the same way as serotonin, which is produced by other cells.
Gonads
The gonads include: in men, the testes, in women, the ovaries. The testes produce sperm, but they also secrete male hormones into the internal environment of the body - androgens, for example testosterone, which is responsible for the manifestation of secondary sexual characteristics. Ovaries in women produce eggs, which are absorbed into the external environment, and female hormones - estrogens, which enter inside. Thanks to these hormones, secondary female sexual characteristics are manifested, they also have a direct effect on the quality of the ovaries. At the same time, both male and female sex glands produce both androgens and estrogens. With normal development, in the body of any man there is a small amount of female hormones, and in the female body there are few male. In the table below, the physiology of the endocrine glands and their hormones can be traced more clearly.
Iron and its hormones | Effects on the body | Hyperfunction | Hypofunction |
Pituitary gland (anterior lobe): thyrotropin | Regulates the secretion of thyroid hormones | Bazedova disease | Gland atrophy |
Corticotropin | It controls the synthesis and secretion of hormones of the adrenal cortex, affects the synthesis of glucocorticoids | Possible Itsenko-Cushing's disease | Decreased adrenal cortex activity |
Somatropin | Growth hormone, provides the development of the body | Gigantism at a young age, acromegaly in adults | |
Prolactin | Promotes milk production | Colostrum, menstrual irregularities | Cessation of lactation |
Follitropin | Stimulates germ cell production | Uterine bleeding | Lack of ovulation and infertility in women, in men - impotence, atrophy of testicles |
Pituitary gland (posterior lobe): vasopressin | Stimulates water reabsorption by the kidneys | Risk of water intoxication | Manifested as diabetes insipidus |
Oxytocin | Stimulates smooth muscle contraction | Hypertension | Diabetes insipidus |
Thyroid: Thyroxine, triiodothyronine | It controls metabolism, increases the excitability of the nervous system | Bazedova’s disease (increased metabolism, goiter develops) | Myxedema (decreased metabolism, swelling appears) |
Parathyroid glands: parathyrin | Regulation of the level of ions in the blood | Bone pain, skeletal deformity, nephrocalcinosis possible | Neuromuscular irritability, cramps, lethargy increases, body temperature decreases. |
Adrenal gland (cortical substance): aldosterone | Normalizes the metabolism of minerals and organic substances, the production of sex hormones | Hypertension at a young age | Addison's disease. Acute or chronic adrenal insufficiency |
Glucocorticoids (cortisol, corticosterone) | Antistress and immunoregulatory effect, effect on metabolism. | Hypercorticism, excess cortisol weakness, excess body weight, increased pressure, skin problems | Addison's Disease |
Adrenal gland (medulla): catecholamines (adrenaline, norepinephrine) | Stress adaptation reactions, fatty acid production, glucose mobilization, energy maintenance | Adrenal medullary tumor | |
Pancreas: insulin | Normalizes blood glucose, synthesizes glycogen | Shock, fainting | Diabetes, increases blood glucose, sugar in urine |
Glucagon | The opposite of insulin |
Gonads: androgens | They have an impact on the development of sexual characteristics, the reproductive system and metabolic processes | Seborrhea, acne. In women - increased hair growth on the arms, legs, face, danger of miscarriage, infertility | Puberty and the development of genital organs are slowed down, breast growth, loss of strength, infertility |
Estrogens, progesterone | The quality of work of female and male genital organs | Atrophy of the prostate, obesity | Osteoporosis |
Pineal gland (pineal gland): melatonin | Regulates the body's circadian rhythms | The aging of the body slows down | Sleep disorders, anxiety, depression, problems of the cardiovascular system |
Thymus gland (thymus): thymosin | Stimulates the production and maturation of lymphocytes | Lymphoid hyperplasia | Immunity decreases, the number of T-lymphocytes in the blood decreases |
As can be seen from the table, the endocrine glands, their hormones and the functions of these hormones are quite diverse.
In order to understand how the human body functions and what needs to be done to maintain its health, it is imperative to understand how the endocrine system works, which regularly supplies our body with the necessary substances.