The work of all organs and systems is coordinated by a number of certain internal factors. Thanks to their well-coordinated mechanism, the human body responds correctly and in time to the action of stimuli. The endocrine system has one of the main roles in these processes.
The basis of this system are the intracretory glands. What should be attributed to the endocrine glands, whether the brain glands belong to them and what features of their work can be distinguished - we will consider below.
Endocrine system and its features
The endocrine apparatus is represented by working cells, some of which are localized, forming an organ, while others are in a free, dispersed state. The organs that belong to this system are called the endocrine glands. The peculiarity of their anatomy is that the excretory ducts along which the secretion is produced are opened inside the body.
The endocrine system performs its regulatory function with the help of produced specific substances - hormones. These chemicals are important functional mechanisms necessary for the proper functioning of the body as a whole.
The function of the endocrine glands
After hormones enter the blood, lymphatic system or cerebrospinal fluid, they begin to act as catalysts. The main functions of the endocrine glands are based on the following processes:
- participation in metabolism;
- coordination of the body and the interaction of all its systems;
- maintaining equilibrium when exposed to external stimuli;
- regulation of growth processes;
- control of sexual differentiation;
- participation in emotional and mental activities.
The active substances that the endocrine gland system produces are specific factors, since each of them also performs a specific function. Hormones act in the human body in the presence of the necessary physical and chemical conditions. This happens depending on the constituent elements of the food that enters the body, and the intermediate stages of metabolism.
Hormones tend to affect the functioning of organs and glands remotely, that is, while away from the target. Another feature is that a change in temperature does not affect the operation of active substances.
Endocrine glands
The endocrine glands include the pituitary, parathyroid and thyroid glands, pancreas, adrenal glands, ovaries and testes, and the pineal gland.
The thyroid gland, the cortical layer of the adrenal glands and the sex glands are considered dependent in their work on the pituitary gland, since the pituitary hormones directly affect the work of the glands.
The remaining glands are not tropic, that is, they do not obey the work of the pituitary system.
Endocrine Glands - Table| Gland name | Location | Hormones produced |
| Pituitary | The lower surface of the brain, in the Turkish saddle | TTG, ATG, LTG, STG, MSH, FSH, ACTH, LH, vasopressin, oxytocin |
| Epiphysis | Between the cerebral hemispheres, behind the interthalamic fusion | Serotonin, Melanin |
| Thyroid | On the front of the neck, takes place between the sternum and the Adam's apple | Calcitonin thyroxine, triiodothyronine |
| Parathyroid gland | Thyroid posterior wall | Parathyroid hormone |
| Thymus | Behind the sternum, in its upper part | Timopoetins |
| Pancreas | At the level of the upper lumbar vertebrae, behind the stomach | Glucagon, insulin |
| Adrenal glands | Above the top of the kidneys | Hydrocortisone, aldosterone, androgens, adrenaline, norepinephrine |
| Testis | Scrotum | Testosterone |
| Ovaries | On the sides of the uterus in the pelvis | Estrogen, progesterone, estradiol |
All endocrine glands are presented here. The table also indicates the localization of the organs and hormones that they produce.
Brain glands
The endocrine glands include the pituitary and pineal gland. Let us consider in more detail the work of each of them.
The pituitary gland is located in the Turkish saddle of the brain, in front is protected by the saddle bones of the skull. This gland is considered the beginning of all metabolic processes occurring in the body. It consists of two parts, each of which produces specific active substances:
- front - an adenohypophysis;
- back - neurohypophysis.
Both lobes are autonomous from each other, because they have a separate innervation, blood circulation and communication with other parts of the brain.
One part of the pituitary gland constantly produces antidiuretic hormone, or vasopressin. The function of this substance is very important for humans, as it controls fluid balance and the functioning of the renal tubules. When the antidiuretic hormone enters the bloodstream, the kidneys begin to retain water in the body, and with a decrease in its amount, give up its external environment.
Oxytocin is a “female” hormone, although it is also present in men. His work is manifested in the ability of the muscles of the uterus to actively contract, that is, the substance is responsible for adequate labor. The same hormone is involved in the removal of the placenta in the postpartum period and lactation after childbirth.
The adenohypophysis is involved in the coordination of the work of some endocrine glands. What endocrine glands are regulated by the anterior pituitary system and with what substances does this occur?
- Thyroid gland - its work is directly dependent on thyroid-stimulating hormone.
- Adrenal glands - regulated by the level of adrenocorticotropic hormone in the blood.
- Gonads - FSH and LH influence their work.
- Prolactin is an adenohypophysis hormone that affects the functioning of the mammary glands during lactation. Somatotropin is a substance whose task is to coordinate the growth of the body and its development, as well as participation in protein biosynthesis.
- Hormones of the pineal gland (pineal gland) are involved in the regulation of human circadian biorhythms , stimulate the immune system, reduce stress and blood pressure, and lower sugar levels.
Thyroid and parathyroid glands
The glands of internal secretion include the thyroid and parathyroid. They are located in one area - at the level of the middle cartilage of the trachea.
Thyroid hormones are considered iodine-free active substances - triiodothyronine, thyroxine. They take part in metabolic processes, regulate the level of glucose uptake by the body’s cells and break down fats. Calcitonin lowers blood calcium.
The main function of the parathyroid gland and its hormone is based on improving the functioning of the nervous and musculoskeletal system, which is achieved by increasing the level of calcium in the body and its absorption by cells.
Functional features of the pancreas
This organ refers not only to the endocrine system, but also to the digestive system. The hormonal function is performed by the so-called islets of Langerhans, which are located in the tail of the gland. These islands have in their composition several types of cells that differ in structure and hormone, which they produce:
- alpha cells: produce the hormone glucagon (regulates carbohydrate metabolism);
- beta cells: produce insulin (reduces the amount of sugar in the blood);
- delta cells: somatostatin secretion;
- epsilon cells: produce the hungry hormone ghrelin.
Adrenal glands and their hormones
The gland is represented by the outer layer of cells (cortical part) and the inner (brain part). Each of the parts produces its own specific active substances. The cortical layer is characterized by the production of glucocorticoids and mineralocorticoids. These hormones are actively involved in metabolic processes.
Adrenaline is a hormone of the internal substance responsible for the functioning of the nervous system. With a sharp increase in its number in the bloodstream appears tachycardia, hypertension, dilated pupils and muscle contraction. Norepinephrine is also synthesized by the inner layer of adrenal cells. Its action is aimed at activating the work of the parasympathetic nervous system.
Gonads
The glands of internal secretion also include the testes and ovaries. The hormones they produce are responsible for the normal functioning of the reproductive system. For women, this is a period of maturation, pregnancy and labor. Male hormones are also responsible for the maturation and appearance of sexual characteristics.
The functions of the endocrine glands are based on direct and feedback. Testes and ovaries belong to the group of tropic organs, since their work directly depends on the adenohypophysis.
The most common misconceptions about the activity of the endocrine system
Many mistakenly believe that all the glands in the human body can be called incretory.
If you ask the following question: “do mammary glands belong to the endocrine glands?”, Then an unequivocal answer will follow - no. The mammary glands belong to the group of excretory organs, that is, their excretory ducts open outward, and not inside the body. In addition, the mammary glands themselves do not produce hormones.
The negative answer will be to the following question: “do lacrimal glands belong to the endocrine glands?” From the point of view of medicine, the lacrimal glands, like the mammary glands, do not belong to the organs of the endocrine apparatus, since they do not have the ability to produce hormone-active substances.