Lecture 13: Intestines

Question 1

What are the three parts of the small intestine? What supplies the small intestine?

Answer 1

Duodenum, jejunum, ileum. Superior mesenteric artery

Question 2

What takes blood from the small intestine? Where does it go?

Answer 2

Superior mesenteric vein, goes to hepatic portal vein in liver.

Question 3

What are the three structures found on the mucosa of the small intestine? What is their collective purpose?

Answer 3

Plicae circularis: folds
Villi: finger-like projections
Microvilli: brush border
Function of all: increase SA for digestion/absorption

Question 4

What do goblet cells do? Lacteals?

Answer 4

GC: produce mucus for protection, less friction
Lacteal: Lymph vessel projections to absorb fats

Question 5

The duodenum curves around the _____ of _______, and has the most dense ______ _________. It is the only site of absorption for what? What structure is found on the duodenum?

Answer 5

Head of pancreas, plicae circularis. Calcium and iron. Hepatopancreatic ampulla.

Question 6

What does the jejunum absorb? What is its arterial supply?

Answer 6

Glucose, amino acids, water, fats. Long vasa recta.

Question 7

What does the ileum absorb? What is its arterial supply?

Answer 7

Fats. Short vasa recta.

Question 8

What immune function does the ileum have?

Answer 8

Lymphoid nodules (T/B cells waiting to attack), also called Payer’s Patches.

Question 9

Which digestive enzymes break down carbs? Fats?

Answer 9

Carbs: amylase, lactase, maltase, sucrase.
Fats: bile salts (liver), lipase

Question 10

Which digestive enzymes break down proteins? Nucleic acids?

Answer 10

Proteins: pepsin, trypsin, chymotrypsin, carboxypeptidase.
Nucleic acids: nucleases

Question 11

Name the 7 steps of the large intestine.

Answer 11

Cecum, ascending colon, transverse colon, descending colon, sigmoid colon, rectum, anus

Question 12

Describe the arterial supply and venous drainage of the large intestine.

Answer 12

Supply: inf mesenteric artery for descending, superior mesenteric for ascending
Drainage: Sup/inf mesenteric, hepatic portal vein

Question 13

What is the role of bacteria in the large intestine?

Answer 13

Ferment: undigested carbs, amino acids, bilirubin
Synthesize: vitamin B, K

Question 14

What are the 4 steps of mechanical digestion in the colon?

Answer 14

1. gastrocolic reflex, when food enters stomach
2. gastroileal reflex, when stomach is full
3. haustral churning, haustra rearrange
4. mass peristalsis, push to rectum