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Anatomy and physiology of the hypothalamic-pituitary system
Anatomy and physiology of the hypothalamic-pituitary system
The hypothalamus is the formation of nervous tissue located in the brain. In the hypothalamus contains a large number of separate groups of nerve cells, called nuclei. The total number of nuclei around 150.
The hypothalamus has many links to different parts of the nervous system and performs many functions that are not yet fully understood, as it is not known, the purpose of many of its nuclei. Now consider not only the hypothalamus as the center of the regulation of the autonomic nervous system, body temperature, but also as endokrinnyy body.
The endocrine function of the hypothalamus is closely connected with the work of the lower brain appendage - the pituitary gland. In cells and hypothalamic nuclei are distinguished:
Hypothalamic hormones - liberiny and statins, which regulate the function of the pituitary gormonprodutsiruyuschuyu.
Tireoliberin - stimulates the production of thyrotropin in the pituitary gland.
Somatostatin - inhibits the production of pituitary growth hormone.
These hormones are synthesized by the hypothalamus, receives a special circulatory system that connects the hypothalamus to the anterior pituitary gland. Two of the nuclei of the hypothalamus produce hormones vasopressin and oxytocin. Oxytocin stimulates the secretion of milk during lactation. Vasopressin, or antidiuretic hormone controls the water balance in the body, under his influence increased water reabsorption in the kidney. These hormones are stored in long processes of nerve cells of the hypothalamus that terminate in the pituitary gland. Thus, the supply of hormones of the hypothalamus oxytocin and vasopressin is stored in the posterior pituitary lobe.
Pituitary gland or the lower brain appendage called the main endocrine gland of the human body. It is located in the bony cavity called the sella turcica. The pituitary gland is located at the base of the brain and is attached to the brain stem, thin. Pituitary stalk on this linked to the hypothalamus. The pituitary gland consists of anterior and posterior lobes. The intermediate fraction from human underdeveloped. In the anterior pituitary, it is called the adenohypophysis, made six of their own hormones. In the back lobe of the pituitary, called the neurohypophysis, accumulate two hormones of the hypothalamus - oxytocin and vasopressin.
Hormones, which produces the anterior lobe of the pituitary:
Prolactin. This hormone stimulates lactation (the formation of milk in the mammary glands).
Somatotropin or growth hormone - regulates growth and is involved in metabolism.
Gonadotropins - luteinizing and follicle-stimulating hormones. They control the sexual function in men and women.
Thyrotropin. Tirotropny hormone regulates the thyroid gland.
Adrenocorticotropin. ACTH stimulates the production of glucocorticoid hormones by the adrenal cortex.
Anterior lobe of the pituitary or adenohypophysis regulates, thus, the work of three target glands.
When failure or removal of the glands of the target, increasing the concentration of the regulatory hormone, as the body tries to restore normal hormone levels. In this case, there are state of insufficiency of glands with excessive production of stimulating pituitary hormones.
When insufficiency of sexual glands arise gipergonadotropny primary hypogonadism (gonadal failure of function with excess level of follicle stimulating hormone and lyutropina).
In case of insufficiency of the adrenal cortex occurs adissonova disease (deficiency of adrenal hormones in the excessive level of adrenocorticotropin).
In case of insufficiency of the thyroid gland occurs primary gipotiroz (deficiency of thyroid hormones in the excessive levels of thyrotropin).
If, however, destroyed or removed pituitary itself - it disappears tropic (stimulating) and tropic hormone function are not produced. In this case, because of lack of stimulatory action of tropic hormones of the pituitary occur: secondary hypogonadotropic hypogonadism. Secondary adrenal insufficiency. Secondary gipotiroz. At the same time disappear as prolactin and growth hormone, and what they do. The development of oxytocin and vasopressin is not violated, because they produce the hypothalamus.
