Exocrine Glands

Glands in the human body are classified as exocrine or endocrine. The secretions of exocrine glands are released through ducts onto an organ's surface, while those of endocrine glands are released directly into the blood. The secretions of both types of glands are carefully regulated by the body.

Exocrine gland secretions include saliva, perspiration, oil, earwax, milk, mucus, and digestive enzymes. The pancreas is both an exocrine gland and endocrine gland; it produces digestive enzymes that are released into the intestine via the pancreatic duct, and it produces hormones, such as insulin and glucagon, which are released from the islets of Langerhans directly into the bloodstream.

Exocrine glands are made up of glandular epithelial tissue arranged in single or multilayered sheets. Exocrine gland tissue does not have blood vessels running through it; the cells are nourished by vessels in the connective tissue to which the glands are attached. Gland cells communicate with each other and nerves via channels of communication which run through the tissue.