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
Parathyroid gland Hyperparathyroidism is most commonly caused by a benign proliferation of chief cells in single gland, and rarely MEN syndrome. This is known as primary hyperparathyroidism, which is generally managed by surgical removal of the abnormal parathyroid gland. Renal disease may lead to hyperparathyroidism. When too much calcium is lost, there is a compensation by the parathyroid, and parathyroid hormone is released. The glands hypertrophy to synthesise more parathyroid hormone. This is known as secondary hyperparathyroidism. If this situation exists for a prolonged period of time, the parathyroid tissue may become unresponsive to the blood calcium levels, and begin to autonomously