Splanchnic Circulation Flashcards
What constitutes the splanchnic circulation?
Celiac artery, superior mesenteric artery, inferior mesenteric artery
What percent of cardiac output goes to splanchnic circulation? What is the rate of oxygen extraction?
20-30% of total CO; extracts 15-20%
What does the majority of splanchnic circulation go?
To the mucosa
What are the three main general mechanisms involved in controlling splanchnic circulation?
Neural, Metabolic, Hormonal
What is the neural control of splanchnic circulation?
Parasympathetics stimulate during the cephalic phase of digestion increase blood flow
What are the hormonal regulators of splanchnic circulation?
Renin-angiotensin system and ADH (vasoconstrictors), and gastrin and CCK (vasodilators)
What is post-prandial hyperemia?
Increase in blood flow to the gut following a meal
What occurs from low splanchnic circulation?
Increased intestinal permeability, host defense mechanisms activated, decrease in gastric pH
What is the ratio of blood supplied to the liver by the hepatic artery and by the portal vein?
Portal vein= 75% and Hepatic a. = 25%
What is the basic pathway through the portal circulation system?
Tissue-> portal vein-> liver-> hepatic vein-> IVC-> heart
What percent of cardiac output is dedicated to hepatic blood supply?
25%
In what structures do hepatic artery blood and portal vein blood mix?
Hepatic sinusoids
What specialized cells regulate the resistance of the hepatic sinusoids?
Hepatic stellate cells
What is the physiologic importance of the large difference in pressures between the hepatic artery blood flow and portal vein flow?
Makes it easier for highly oxygenated blood to perfuse the liver
True or False: Liver autoregulates its own blood supply
True
