Pituitary

The pituitary gland divides into the adenohypophysis and the neurohypophysis. Read more about the structure and function of the pituitary gland!

Pituitary

The pituitary is the pituitary gland - the interface between the endocrine system and the nervous system. In the pituitary gland, almost all the important hormones that occur in the body periphery are sometimes produced and secreted, sometimes only stored and then released. Read all important information about the pituitary gland: Function, structure and disorders that can occur in case of malfunction!

What is the pituitary gland?

The pituitary (pituitary gland) is an important hormone gland in the brain. It is divided into two parts:

  • Adenohypophysis (anterior pituitary gland, HVL): contains glandular tissue (is hormone-active); accounts for three-quarters of the institution;
  • Neurohypophysis (pituitary backbone, HHL): contains nerve tissue (nerve fibers and neuroglia).

Between the anterior and posterior lobes of the pituitary gland there is a small lobe (Pars internedia).

Both areas - adenohypophysis and neurohypophysis - are supplied by various vessels that enter the pituitary gland and form a vascular network inside. Blood from the hypothalamus flows via a portal vein system via the pituitary stalk (infundibulum) to the pituitary gland.

What is the function of the pituitary gland?

The pituitary gland produces and secretes various important hormones. Secretion is controlled by various releasing (releasing) and inhibiting (inhibitory) hormones of the hypothalamus.

In the anterior pituitary, the following pituitary hormones are produced and secreted:

  • Somatotropin (STH): produced in alpha-1 cells; as growth hormone important for normal length growth;
  • Corticotropin (ACTH): produced in the basophilic beta cells; stimulates the adrenal cortex to grow, as well as to form and secrete glucocorticoids, which indirectly influence carbohydrate metabolism
  • Thyrotropin (TSH): also produced in basophilic beta cells; controls the function of the thyroid gland
  • Lipotropin: acts lipolytic (fat-degrading) and thus influences the lipid metabolism
  • Follicle stimulating hormone (FSH): together with the luteinizing hormone (LH) it promotes follicular maturation in women and sperm production (spermatogenesis) and the development of seminiferous tubules in men
  • Prolactin (PRL): is formed from the eighth week of pregnancy acts on the mammary gland and milk production

In the posterior pituitary, the following hormones are accumulated, which are formed by the hypohyseal nuclei of the hypothalamus:

  • Oxytocin: causes the contraction of the uterine muscles at birth (labor pains) and mammary muscle cells (stimulation of milk secretion)
  • Vasopressin or adiuretine (ADH): inhibits the elimination of water through the kidneys (antidiuretic effect) and ensures a constriction of the blood vessels

These hormones stored in the posterior pituitary gland are transmitted from there via the portal circulation into the systemic circulation.

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Where is the pituitary?

The pituitary gland is located in the pituitary pit, the depression of the Turkish saddle. With its funnel-shaped stalk, the pituitary hangs at the bottom of the diencephalon.

What problems can the pituitary cause?

Hyperfunction of the alpha-1 cells in the pituitary anterior lobes leads to gigantism in adolescents in whom the growth joints are still not open. In adults, there is acromegaly - an enlargement of the nose, chin, fingers and toes.

A benign tumor of the pituitary anterior lobe, a pituitary adenoma, is the most common pituitary disease. It can consist of different cell types. If the adenoma is hormone-active, the pituitary gland produces an excessive amount of the hormone that the cells in question produce - with correspondingly increased hormone action. The most common is prolactinoma, which releases excess prolactin. In women, there is a flow of milk and the absence of the rule, in men an androgen deficiency and infertility.

A pituitary adenoma may also be hormonally inactive. Then you notice it first through its mass and its possible effects. Thus, by enlarging the pituitary gland, the Turkish saddle is widened, which affects the directly adjacent chiasm opticum (optic nerve intersection) in the middle fossa. Direct consequences include a bitemporal hemianopia (the outer visual field of both eyes is narrowed) and a decrease in vision when the optic nerve (optic nerve) is damaged by the growth and pressure of the adenoma.

Hypopituitarism is a hypofunction of the anterior pituitary due to inflammation, tumors or drugs. As a result, the secretion of growth hormones, thyroid hormones and sex hormones is reduced or completely eliminated. As a result, growth, physical development, metabolism and fertility are disturbed.

Diabetes insipidus is deficient in the hormone ADH, which is stored in the posterior pituitary gland. The water balance of the body is then disturbed. Symptoms include lack of fluid due to increased production of urine and urine, constant thirst, dry skin and mucous membranes, constipation, sleep disorders, irritability and cramps to collapse.

The pituitary gland also controls the adrenal cortex. If the function of the pituitary gland is limited, the adrenal cortex also produces fewer hormones.

In a restricted pituitaryFunction - when TSH and somatotropin, which indirectly increase blood sugar levels, are diminished - hypoglycaemia (hypoglycemia) occurs.


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