Physiology of the mesenteric circulation.

The purpose of this educational exercise is to describe some of the salient features of the physiology of the mesenteric circulation, focusing particularly on the regulation of its blood flow. The reader is referred to several recent reviews of the subject that are more extensively referenced with original sources (5, 6, 10, 11). Although the terms “mesenteric circulation” and “splanchnic circulation” are sometimes used synonymously, they are distinct: the mesenteric circulation refers specifically to the vasculature of the intestines, whereas the splanchnic circulation provides blood flow to the entire abdominal portion of the digestive system. In a 70.kg resting adult human male in good health, the major inflow vessel of the mesenteric circulation, the superior mesenteric artery, delivers about 12% of the cardiac output and is therefore unsurpassed in size among all branches of the entire aorta. This vessel supplies the entire small intestine, the proximal half of the colon, and part of the pancreas. to the heart