Explanation:
The pituitary gland is a small gland located from the base of the brain (‘’pea on a string’’). It is a small gland (500 mg). The pituitary gland lies in the hypophyseal fossa of the sphenoid bone below the hypothalamus. The hypothalamus is a structure of the diencephalon of the brain located anterior and inferior to the thalamus.
The pituitary gland is a part of the human endocrine system. Its main function is to produce and secrete hormones into the circulation. Consequently, via these hormones it has a link to the thyroid gland, reproductive organs and adrenal glands.
The pituitary gland has two parts: anterior and posterior lobes. The posterior lobe receives messages from the brain through hypothalamus and produces specific hormones. Those hormones affect many system organs and tissues in the body. The posterior lobe is therefore called master gland as it stimulates all the other hormones. Vasopressin is important in the onset of diabetes melliuts. In case of insufficient secretion of vasopressin there a disease called diabetes insipidus (the organism loses the capacity to concentrate urine). The hyperproduction of vasopressin leads to the syndrome of the inappropriate antidiuretic hormone (SIADH).
The anterior pituitary lobe is the front lobe of the pituitary gland. It is located at the floor of the brain (sella turcica).
The main function of anterior lobe is to control chemical and water balance in the organism, control growth and metabolism, regulate sexual functions and stimulate growth and maturation of the gonads. The most important hormones secreted in the anterior lobe are GH, TSH, ACTH, prolactin, FSH, LH. GH (the growth hormone) stimulates the growth of bones, muscles and other tissue by increasing protein synthesis. GH affects protein, fatty acids and carbohydrate mechanisms. In case of decreased production of GH, there is an abnormal development of the pituitary gland. The release of GH is stimulated by GHRH, and inhibited by GHIRH.
TSH is stimulated by thyrotropin-releasing hormone (TRH) produced in the hypothalamus. It is inhibited by somatostatin from the hypothalamus. The main function of TSH is to activate the thyroid gland to secrete hormone thyroxin. In the case of overexpression of TSH, there is an increased secretion of thyroxin and the enlarged thyroid gland.
ACTH (adrenocorticotropic hormone) is stimulated by corticotropin-releasing hormone (CRH) from the hypothalamus. ACTH stimulates the adrenal cortex to produce glucocorticoids. The secretion of ACTH is inhibited by high blood levels of ACTH.
Prolactin (lactogenic hormone) is stimulated by prolactin-releasing hormone (PRH) from the hypothalamus. It is inhibited by dopamine produced in the hypothalamus. Prolactin stimulates the production of milk in the mammary glands. Prolactin hypersecretion may lead to the onset of erectile dysfunction. In males, gonadotropins (LH, FSH) stimulate the testicles to secrete testosterone. In females, they simulate the release of ovym by the ovaries and later the formation of corpus luteum and progesterone production.
