Hypophysis

Tuesday, July 28, 2009

The hypophysis, also called pituitary gland, is an endocrine gland about the size of a pea. It is a protrusion off the bottom of the hypothalamus at the base of the brain, and rests in the sella turcica ( a small, bony cavity) covered by a dural fold (diaphragma sellae). The hypophysis produces hormones that regulate homeostasis, and stimulate other endocrine glands. It is functionally connected to the hypothalamus by the median eminence.

The hypophysis is situated at the base of the brain and is connected to the hypothalamus by the pituitary stalk. hypothalamic releasing factors stimulate the release of pituitary hormones. It consists of two lobes: 1) the adenohypophysis, or the anterior pituitary; 2) the neurohypophysis, or the posterior pituitary. Both of its lobes are under the control of the hypothalamus.

The adenohypophysis secretes important endocrine hormones, such as adrenocorticotropic hormone , Thyroid-stimulating hormone, PRL, GH, endorphins, FSH, and LH. These hormones are released from the anterior pituitary under the influence of the hypothalamus. Hypothalamic hormones are secreted to the anterior lobe by way of a special capillary system, called the hypothalamic-hypophyseal portal system.

The neurohypophysis stores and releases oxytocin, most of which is released from the paraventricular nucleus in the hypothalamus, and vasopressin and AVP, arginine vasopressin, the majority of which is released from the supraoptic nucleus in the hypothalamus.

The hypophysis hormones help control some of the following body processes: growth, blood pressure, breast milk production, sex organs, thyroid gland, metabolism, etc.