Lecture 2

Question 1

How is vitamin B12 absorbed and where?

Answer 1

in the ileum after it has been bound by intrinsic factor produced in the wall of the stomach

Question 2

Once inside the epithelial cell of the ileum, what happens to B12?

Answer 2

the intrinsic factor is cleaved from the B12 and B12 enters the portal circulation to be stored in the liver

Question 3

What artery supplies the stomach and spleen?

Answer 3

celiac

Question 4

What artery supplies the small intestine, pancreas, and proximal colon?

Answer 4

cranial mesenteric artery

Question 5

What artery supplies the majority of the colon?

Answer 5

caudal mesenteric artery

Question 6

What artery supplies the liver?

Answer 6

the hepatic artery

Question 7

What is the venous drainage of the GI tract?

Answer 7

portal vein to liver sinusoids to central veins of hepatic lobule to hepatic vein to posterior vena cava

Question 8

What occurs to blood flow after a meal?

Answer 8

it increases to the gut for 3-6 hours

Question 9

What are local factors of increased blood flow to the gut?

Answer 9

prostaglandins E and I, vasodilator hormones, vasodilator kinins, and low oxygen

Question 10

What vasodilator hormones increase local blood flow?

Answer 10

gastrin, secretin, and CCK-endocrine

Question 11

What vasodilator kinins increase local blood flow?

Answer 11

bradykinin and kallidin paracrine

Question 12

What nervous system increases blood flow?

Answer 12

parasympathetic nervous system

Question 13

What nervous system directly decreases blood flow?

Answer 13

sympathetic nervous system

Question 14

Normally, what percentage of oxygen is shunted from villous arterioles to venules?

Answer 14

80%

Question 15

How can heat stress affect the gut?

Answer 15

you can lose integrity of the guts tight cell junctions leading to loss of absorptive capacity and loss of ability to keep bacteria out