The pituitary gland (pituitary gland or lower cerebralappendage) is the endocrine organ that is located at the base of the brain. More specifically, it is on its lower surface, in the bone pocket called the Turkish saddle. This gland in a man of very small size, about a pea, is a rounded formation weighing only 0.5 g. But despite such small size, the role of hormones produced by the pituitary gland is enormous.
This small gland is the main organ of our entire endocrine system. Hormones, which it produces, affect the following functions of the body:
Functions and hormones of the pituitary gland, which he produces, are closely related. In order to understand this question in more detail, let us first consider the structure of this endocrine gland.
It consists of three main parts:anterior, posterior and intermediate, which differ in their origin and structure. The pituitary gland begins to form in the embryo on the 4th-5th week of intrauterine development. The anterior part of it is formed from the epithelial surface of the posterior wall of the oral cavity, the so-called Ratke pocket, in the form of a small oblong outgrowth. In the process of embryonic development, it grows in the direction of the intermediate brain.
Задняя доля формируется немного позднее передней from the nervous tissue of the intermediate brain, there these parts are joined together. Even later, the intermediate portion of the pituitary gland is formed. It consists of a thin layer of cells. All three parts of the pituitary gland are in fact separate secretory glands, and each of them produces its own hormones. The pituitary body (hormones and its functions) takes a huge part in the work of the entire endocrine system of man.
This proportion is called adenohypophysis and isthe main mass of the gland (70%). It consists of various kinds of endocrine glandular cells. Each cell type of this share produces its own hormone. These endocrine cells are called adenocytes. There are two types of adenocytes: chromophilic and chromophobic, they both synthesize hormones:
Pituitary hormones - their physiological role in the human body is enormous.
Somatotropin (or growth hormone) is not producedconstantly, its release occurs only 3-4 times a day. Its secretion increases markedly during periods of sleep, during heavy physical exertion and during fasting. The production of this hormone persists throughout the life of a person, but decreases with age. Under the influence of growth hormone in the cells, the breakdown of fats and carbohydrates occurs. As a result, cell action and protein synthesis are enhanced under the influence of somatomedins produced in the liver, thus bone growth occurs.
If somatotropin synthesis for some reasoninsufficient, then dwarfism develops. In this case, all the proportions of the body are preserved, the physique is, as a rule, normal. Thus, the lack of pituitary function directly affects the growth of a person.
Excessive secretion of somatotropin causesgigantism. If hypersecretion occurs in childhood, all proportions of the body are preserved, and in adulthood, enhanced production of it leads to acromegaly. This is manifested by a disproportionate lengthening of the limbs, an increase in the nose and chin, as well as the tongue and all digestive organs.
This hormone regulates the activity of the thyroid.glands. Under its influence, secretion of triiodothyronine and thyroxin occurs. It activates the enzyme adenylate cyclase, which affects the absorption of iodine by the cells of the thyroid gland. In addition, under the influence of TSH, protein metabolism occurs: the production of nucleic acids and protein synthesis increases, growth increases and the size of thyroid cells increases.
TSH synthesis is able to increase underexposure to cold. The cold reaction enhances the production of thyroid hormones, which leads to more heat being produced by the body. Glucocorticoids are able to inhibit the production of TSH, the same happens under the influence of anesthesia, a painful reaction or injury.
Excessive secretion of thyroid-stimulating hormone is manifested by clinical symptoms of thyrotoxicosis (hyperthyroidism).
АКТГ синтезируется неравномерно в течение суток.The greatest concentration is observed in the morning from 6.00 to 8.00, the minimum - in the evening from 18.00 to 23.00. ACTH regulates the synthesis of corticosteroids, which are secreted by adrenal cortex cells. The secretion of corticosteroids increases with strong emotional states, such as fear, anger, chronic stress. Thus, ACTH has a direct impact on a person’s emotional balance. In the same way, the synthesis of ACTH is enhanced by strong cold and pain reactions, severe physical stress. Hypoglycemia also stimulates the production of ACTH.
Excessive secretion of this hormone canobserved in pituitary adenoma, a disease called Itsenko-Cushing's disease. Manifestations of it are: hypertension, obesity, and body fat accumulates on the body and face, and the limbs remain normal, increasing the concentration of sugar in the blood, reducing the immune defense.
Insufficient production of ACTH leads to a decrease in the synthesis of glucocorticoids, and this, in turn, is expressed by impaired metabolism and reduced endurance of the body to the influence of the environment.
They control the sex glands as women,and men. For example, folliclotropin in women stimulates the formation of follicles in the ovaries. In the male half, this secret affects the development of the prostate and spermatogenesis (sperm production).
Luteoptropin regulates the formation of androgens - male hormones (testosterone, androstenedione, etc.) and estrogen - female hormones (estriol, estradiol, etc.).
Thus, the pituitary gland and its hormones are involved in the work of almost all organs.
The posterior lobe of the pituitary gland is called the neurohypophysis, it consists of cells of the epidermis, called pituitary cells. The neurohypophysis, as well as the adenohypophysis, produces hormones. Hormones of the posterior lobe of the pituitary:
All of these hormones perform their specific functions in the human body. Let's talk about some of them separately.
So, the hormone oxytocin affects muscle contraction.uterus during labor. On the surface of the cell membrane are special receptors that are sensitive to oxytocin. During pregnancy, this hormone does not rise to a level that can cause contractile activity of the uterus. Only immediately before the birth itself, under the influence of the female hormones estrogen, sensitivity to oxytocin increases and childbirth occurs. It also leads to a reduction in myoepithelial cells located in the mammary glands, which stimulates milk production.
The effect of oxytocin on the male body is not well understood. It is believed that it can affect the functioning of the intestinal, gall and bladder walls.
Vasopressin (also called antidiuretichormone - ADH) performs two functions in the body. It has an antidiuretic effect, i.e. enhances the reabsorption of water in the collecting tubules of the kidneys and, in addition, it affects the smooth muscle of the arterioles (small blood vessels extending from the arteries), i.e. able to narrow their clearance. In physiological concentration, this effect does not cause a significant effect on the body, and in pharmacological doses, when artificially administered ADH in its pure form, arterioles are significantly narrowed, which causes an increase in pressure.
Thus, the hormones of the posterior lobe of the pituitary glandtheir lack of production can cause diabetes insipidus (an antidiuretic effect) in which up to 15 liters of fluid can be lost per day (excreted with urine). This loss must be constantly replenished. People with diabetes insipidus experience constant thirst.
The intermediate share also produces a number of hormones,for example, these include the melan-stimulating hormone, which is responsible for the color of the skin and hair. Under its influence, pigment melanin is formed, which plays a significant role in the race of people.
Pituitary gland (hormones and its functions are described above)It works in conjunction with the hypothalamus (the diencephalon region), more precisely, its neurosecretory nuclei. Together they form the hypothalamic-pituitary system. It controls the work of all peripheral endocrine glands. Impaired pituitary function (hormonal disorders) leads to serious consequences. Doctors endocrinologists deal with such problems.
The pituitary gland and its functions in the body are very important. The proper operation of all organs and systems depends on them.
If problems arise in such a small endocrine gland as the pituitary gland, its hormones and functions do not work correctly, and serious pathologies can develop in the human body:
Such diseases can occur ifthe pituitary gland does not synthesize one hormone or several, or, conversely, too many of them enter the blood. The functions and hormones of the pituitary gland for the body are important. Their violations can cause a number of pathologies that require a serious approach and often require hormonal therapy.
