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
Adrenocortical hormone the pituitary gland or adrenal gland. In either case, treatment may rely on removal of the tumor or of the adrenal glands. Without the adrenal glands, the human body is unable to supply the hormones it produces and therefore requires hormone replacement therapy. Addison’s disease is an autoimmune disorder that affects the adrenal cortex such that it is unable to efficiently secrete hormones. The immune system specifically targets the cells of the adrenal cortex and destroys them, but Addison’s disease can also be caused by a severe infection such as tuberculosis. Some symptoms include hypoglycemia and decreased blood sodium levels