13 Anat, Phys, and Path of Small Intestine Part 1

Question 1

13.3 Distinguish between the different sections of the small intestine

Answer 1

Duodenum - First 10-12 inches - ends at a sharp bend called the duodenojejunal flexure

Jejunum - 8 ft

Ileum - 12 ft - Joins large intestine at the ileocecal valve

Question 2

13.4 Identify the key histologic features of the small intestine that enable it to provide optimal absorption

Answer 2

Maximal surface area accomplished through:

1. Pilcae circulares
2. Villi
3. Microvilli

Question 3

13.5 Intestinal villi contain crypts of Lieberkuhn. What kind of cells are found in the crypts?

Answer 3

1. Surface absorptive cell
2. Goblet cell
3. Enteroendocrine cell
4. Regenerative cell
5. Paneth cell

Question 4

13.5 What do enteroendocrine cells do?

Answer 4

Secrete CCK, secretin, GIP (DNES cells; APUD cells)

Question 5

13.5 What do paneth cells do?

Answer 5

Secrete lysozyme and other antibacterial agents

Question 6

13.9 What does pancreatic amylase do?

Answer 6

Degrades polysacharides into disaccharides and “oligosaccharides”

Question 7

13.9 What enzyme degrades disaccharides?

Answer 7

A group of brush border enzymes called disaccharidases

Question 8

13.10 Glucose and galactose are absorbed through what kind of cotransporter?

How does this cotransporter function?

Answer 8

A Na-dependent cotransporter known as SGLT 1.

A high luminal concentration of Na faciliates absorption of these 2 sugars against their gradients

Question 9

13.10 Fructose is absorbed through what kind of process and transporter?

Does this process require Na?

Answer 9

Facilitated diffusion via glucose transporter 5 (GLUT5)

Does not require Na

Question 10

13.10 All monosaccharides are transported out of the enterocytes and into capillaries by what process and transporter?

Answer 10

Facilitated diffusion (GLUT2)

Question 11

13.12 To what extent will the stomach digest proteins?

Answer 11

It will denature proteins, but it is not as effective at cleaving off individual amino acids (pepsin does some of this)

Question 12

13.12 Where are amino acids cleaved off?

Answer 12

Occurs mainly at the brush border with aminopeptidases and with the active pancreatic enzymes (proteases)

Question 13

13.13 What two transport mechanisms are used for amino acid absorption?

Answer 13

1. Na-dependent cotransporter (like glucose)

2. Facilitated diffusion (like fructose)

Question 14

13. 6 What kind of epithelilal cells make up the intestinal villi?
    (e. g. Simple/Stratified, squamous, columnar, cuboidal)

Answer 14

Simple columnar epithelial cells