ABSTRACT
The blood vessels of the gastrointestinal (GI) system are part of a more extensive system called the splanchnic circulation. The splanchnic circulation includes the gut, pancreas, liver, and spleen. Splanchnic blood flow courses through the gut, spleen, and pancreas and then flows immediately into the hepatic circulation by way of the portal vein. Blood then flows through minute liver sinusoids and re-enters the systemic circulation via the hepatic veins. This complex secondary flow of blood allows the reticuloendothelial system of the sinusoids to remove harmful bacteria and other substances that could potentially enter the systemic circulation. Maintenance of an adequate blood supply to the intestines is important in insuring normal intestinal homeostasis. Splanchnic blood flow is influenced by several factors including the status of the normal systemic circulation, the degree of collateral blood flow, and the exposure to exogenous and endogenous neuro-humoral factors. Maintenance of normal splanchnic blood flow is important in preserving intestinal motility, absorption of nutrients, and immune function. This chapter will examine the anatomy and physiology of intestinal blood flow and will then examine the pathophysiology of the clinical disorders that result from altered intestinal blood flow.
