ENDOCRINE SYSTEM
Human endocrine system Group of ductless glands that regulate body processes by secreting chemical substances called hormones . Hormones act on nearby tissues or are carried in the bloodstream to act on specific target organs and distant tissues. Diseases of the endocrine system can result from the oversecretion or undersecretion of hormones or from the inability of target organs or tissues to respond to hormones effectively. It is important to distinguish between an endocrine gland , which discharges hormones into the bloodstream, and an exocrine gland , which secretes substances through a duct opening in a gland onto an external or internal body surface. Exocrine gland act on local tissues near the duct openings . In contrast, the hormones secreted by endocrine glands are carried by the circulation to exert their actions on tissues remote from the site of their secretion. The endocrine system, in association with the nervous system and the immune system , regulat
