Insulin effect of increasing glucose uptake and storage. Finally, insulin is degraded, terminating the response. In mammals, insulin is synthesized in the pancreas within the beta cells. One million to three million pancreatic islets form the endocrine part of the pancreas, which is primarily an exocrine gland. The endocrine portion accounts for only 2% of the total mass of the pancreas. Within the pancreatic islets, beta cells constitute 65–80% of all the cells. Insulin consists of two polypeptide chains, the A- and B- chains, linked together by disulfide bonds. It is however first synthesized as a single polypeptide called preproinsulin in
Pituitary gland secretes hormones. All releasing hormones (-RH) referred to, can also be referred to as releasing factors (-RF). Somatotropes: Corticotropes: Thyrotropes: Gonadotropes: Lactotropes: 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-hypophysial portal system. There is also a non-endocrine cell population called folliculostellate cells. The intermediate lobe synthesizes and secretes the following important endocrine hormone: The posterior pituitary stores and secretes (but does not synthesize) the following important endocrine hormones: Magnocellular neurons: Hormones secreted from the pituitary gland