GI Blood Flow Flashcards
What vessels make up the splanchnic circulation?
Blood flow from the gut, spleen, pancreas, and liver and directly into the liver by way of the portal vein. Blood then passes through liver sinusoids and leaves via hepatic veins emptying into the vena cava.
Which hormones are released from the mucosa during digestive and can act as vasodilator substances causing increased blood flow during GI activity?
CCK, vasoactive intestinal peptide, gastrin and secretin.
Two kinins, kallidin and bradykinin are also powerful vasodilators released during digestion.
Describe countercurrent blood flow in the villi, and it what situation this can be harmful to the gut?
The arterial flow into the villus and venous flow out are in opposite directions and allow the vessels to lie closely to one another. Oxygen diffuses from arterioles into venules without ever reaching the tips of the villi (80% makes a short circuit route). Generally not harmful, but in shock oxygen deficiency is significantly worse causing ischemic death.
