Podcast
Questions and Answers
What do the small mesenteric arteries form in the submucosa of the gastrointestinal tract?
What do the small mesenteric arteries form in the submucosa of the gastrointestinal tract?
- Extensive vascular network (correct)
- Extensive neural network
- Extensive lymphatic network
- Extensive muscular network
Which artery carries more than 10% of the cardiac output to supply the gastrointestinal tract?
Which artery carries more than 10% of the cardiac output to supply the gastrointestinal tract?
- Hepatic artery
- Superior mesenteric artery (correct)
- Celiac artery
- Inferior mesenteric artery
What is the purpose of the countercurrent exchange system in the villi of the gastrointestinal tract?
What is the purpose of the countercurrent exchange system in the villi of the gastrointestinal tract?
- To enable diffusion of O2 from arterioles to venules (correct)
- To enable diffusion of CO2 from venules to arterioles
- To maintain a constant blood flow rate in the capillaries
- To prevent shunting of O2 from arterioles to venules
What happens when intestinal blood flow is very low?
What happens when intestinal blood flow is very low?
What is the primary neural control of the mesenteric circulation?
What is the primary neural control of the mesenteric circulation?
What effect does the agonist isoproterenol have on the mesenteric circulation?
What effect does the agonist isoproterenol have on the mesenteric circulation?
What is the principal mechanism responsible for autoregulation in the intestinal circulation?
What is the principal mechanism responsible for autoregulation in the intestinal circulation?
What effect does adenosine have on the mesenteric vascular bed?
What effect does adenosine have on the mesenteric vascular bed?
What contributes to the hyperemia of the intestinal circulation during food ingestion?
What contributes to the hyperemia of the intestinal circulation during food ingestion?
Which products of digestion are potent vasodilators in the mesenteric circulation?
Which products of digestion are potent vasodilators in the mesenteric circulation?
Study Notes
Mesenteric Arteries
- Small mesenteric arteries form the submucosal plexus in the submucosa of the gastrointestinal tract.
- The superior mesenteric artery is the largest branch from the abdominal aorta and carries more than 10% of the cardiac output to supply the gastrointestinal tract.
- The countercurrent exchange system in the villi of the gastrointestinal tract helps maintain a high oxygen tension in the villus tip, even during periods of low blood flow.
Intestinal Blood Flow, Regulation and Autoregulation
- When intestinal blood flow is very low, the villi can become ischemic and may even necrosis.
- The sympathetic nervous system is the primary neural control of the mesenteric circulation.
- The agonist isoproterenol causes vasodilation in the mesenteric circulation.
- The metabolic theory is the principal mechanism responsible for autoregulation in the intestinal circulation.
- Adenosine is a potent vasodilator in the mesenteric vascular bed. This promotes local blood flow and oxygen delivery.
Hyperemia and Vasodilator Effects
- Hyperemia during food ingestion is caused by several factors, including:
- Mechanical distention of the gut
- Hormonal effects (e.g., gastrin, secretin, cholecystokinin)
- Increased metabolism resulting from digestive processes
- Products of digestion, such as fatty acids and amino acids, are potent vasodilators in the mesenteric circulation.
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Description
Test your knowledge of the blood supply to the gastrointestinal tract and the vascular network within the submucosa. This quiz covers the celiac, superior mesenteric, and inferior mesenteric arteries, as well as the arterial branches and arterioles within the intestinal walls.
