The pyloric mucosa of the stomach secretes gastrin which stimulates the gastric glands of the stomach to secrete gastric juice and the pancreas to secrete pancreatic juice, both of which juices are essential for digestion to occur properly. The mucosa of the duodenum also helps regulate digestion by secreting the hormones secretin and cholecystokinin. When stimulated by the acidity of food arriving from the stomach, the mucosa of the duodenum releases secretin which inhibits gastric juice secretion and stimulates the flow of pancreatic juice into the duodenum. When stimulated by the presence of fats, the mucosa releases cholecystokinin which stimulates the gall bladder to release bile.
Of the endocrine tissues that function only to secrete hormones, the hypothalamus portion of the brain and the pituitary gland together regulate the greatest number of the body's life functions. The hypothalamus secretes releasing hormones which act to stimulate or inhibit the anterior lobe of the pituitary gland to release or stop the flow of its hormones. The hormones of the anterior pituitary, in turn, target many different tissues in the body including many endocrine tissues. The anterior pituitary, although structurally attached to the posterior pituitary, arises from different embryonic material than the posterior pituitary and remains functionally distinct from the posterior pituitary. The hormones released by the anterior pituitary that target non-endocrine tissues are prolactin, which stimulates milk production in the mammary glands of the female after the birth of a baby, and
