Ghrelin is secreted primarily by the stomach and appears to play an impoant role in the central control of food intake. It also stimulates growth hormone secretion by acting directly on receptors in the pituitary. Cholecystokinin (CCK) is secreted by cells in the mucosa of the upper small intestine. It has a plethora of actions in thegastrointestinal system, but the most impoant appears to be the stimulation of pancreatic enzyme secretion, the contraction of the gallbladder (the action for which it was named), and relaxation of the sphincter of Oddi, which allows both bile and pancreatic juice to flow into the intestinal lumen. The neuropeptide orexin(hypocretin)increases energy expenditure paially through increasing spontaneous physical activity. when growth hormone is secreted into your bloodstream, it triggers the liver to produce a hormone called insulin-like growth factor -1.IGF-1 stimulates the growth of bones and other tissues.REF: GANONG&;S REVIEW OF MEDICAL PHYSIOLOGY, KIM BARRETT, HEDDWEN BROOKS, SCOTT BOITANO, SUSAN BARMANTWENTY THIRD EDITIONPAGE NO:443,448