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
Endocrine gland gonads in both sexes. FSH stimulates sex cell production; LH stimulates gonadal hormone production. Gonadotropin levels rise in response to gonadotropin-releasing hormone (GnRH). Negative feedback of gonadal hormones inhibits gonadotropin release. Prolactin (PRL) promotes milk production in human females. Its secretion is prompted by prolactin-releasing hormone (PRH) and inhibited by prolactin-inhibiting hormone (PIH). The neurohypophysis stores and releases two hypothalamic hormones: The thyroid gland is located at the front of the neck, in front of the thyroid cartilage, and is shaped like a butterfly, with two wings connected by a central . Thyroid tissue consists of follicles with stored protein