Anterior pituitary function
Anterior pituitary function
Cells of the anterior lobe (make up 80% of the mass of the pituitary gland) synthesize and secrete several hormones necessary for the growth and development of the organism, as well as for the stimulation of certain target glands.
Adrenocorticotropic hormone (ACTH).
ACTH is also known as corticotropin. Corticotropin-releasing hormone (CRH) is the primary stimulator of ACTH release, but antidiuretic hormone plays a role in stress. ACTH stimulates the adrenal cortex, release of cortizol and, slightly, androgens, such as dehydroepiandrosterone (DHEA). Circulation in the blood of cortisol and other glucocorticoids (including exogenous glucocorticoids) inhibits the excretion of CRH and ACTH. The axis of the KRG-ACTH-cortisol is a central component in response to stress. Without ACTH, the adrenal cortex atrophies and the release of cortisol practically stops.
Thyroid-stimulating hormone (TSH). TSH regulates the structure and function of the thyroid gland and stimulates the synthesis and secretion of thyroid hormones.The synthesis and secretion of TSH is stimulated by hypothalamic thyrotropin-releasing hormone (TRH) and is inhibited (with negative feedback) by thyroid hormones circulating in the blood.
Luteinizing (LH)and follicle-stimulating (FSH) hormones. LG and FSH control the production of sex hormones. The synthesis and secretion of LH and FSH are stimulated by gonadotropin-releasing hormone (GRG) and are inhibited by estrogen and testosterone. In women, LH and FSH stimulate the development of ovarian follicles and ovulation. In men, FSH acts on Sertoli cells and is essential for spermatogenesis; LG acts on the Leydig cells of the testes, stimulating testosterone biosynthesis.
Growth Hormone (STH)or growth hormone. GH affects growth and regulates metabolism. Somatotropin-rele-hormone (HGH) is the main stimulant, and somatostatin is an inhibitor of GH synthesis and secretion. STH controls the synthesis of insulin-like growth factor 1 (IGF-1, aka somato-medina-C), which largely controls growth. Despite the fact that IGF-1 is produced by many tissues, the liver is its most important source. The metabolic effects of GH are biphasic.The STG initiates an in-sulina-like effect, increasing the intake of glucose and fat by muscles, stimulating the consumption of amino acids and protein synthesis in the liver and muscles and inhibiting lipolysis in adipose tissue. After a few hours, a deeper anti-insulin-like metabolic effect is observed. It includes the inhibition of the consumption and use of glucose, an increase in plasma glucose and an increase in lipolysis. This leads to an increase in the blood content of free fatty acids. STH levels increase with physical activity, maintaining blood glucose levels and mobilizing fat as an alternative to a metabolic energy source. Then the production of GH is reduced. Recently, the hormone ghrelin, produced in the bottom of the stomach, was released. Ghrelin causes the release of growth hormone from the pituitary gland, increases appetite and improves memory.
Prolactin.Prolactin is produced by so-called lactotrophic cells, which make up about 30% of the cells of the anterior pituitary gland. During pregnancy, the pituitary gland is doubled, largely due to hyperplasia and hypertrophy of lactotrophic cells. In humans, the main function of prolactin is to stimulate milk production.In addition, the secretion of prolactin is observed in the period of sexual activity and stress. Prolactin may be a sensitive indicator of pituitary dysfunction; prolactin is a hormone that is often produced in large quantities in pituitary tumors, and this is often the first hormone whose deficiency develops with infiltrative lesions or compression of the pituitary by a tumor.
Other hormones.Some other hormones are produced in the anterior lobe of the pituitary gland. These include proopio-melanocortin (POMA, which causes an increase in ACTH), and -melanocite-stimulating hormone (MSH), α-lipotropic hormone (-LPG), enkephalins and endorphins. POMC and MSH can cause hyperpigmentation of the skin and are important clinical indicators for diseases in which ACTH levels increase markedly (for example, Addison's disease, Nelson's syndrome). The function LPP is unknown. Enkephalins and endorphins are endogenous opioids that bind to opioid receptors and activate them, affecting the central nervous system.
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