Intestinal Physiology

Question 1

How is vitamin B12 absorbed?

Answer 1

It must be combined with intrinsic factor (secreted from parietal cells along with HCl)

They bind to the sites at the lower portion of the ilium where they are taken in by endocytosis

Question 2

Which vitamins are in miscelles?

Answer 2

Vitamin A, D, E & K

Question 3

There are 2 forms of pepsinogen. What is the difference between them?

Answer 3

Pepsinogen 1 = HCl secreting region

Pepsinogen 2 = Pyloric region

Question 4

What is the difference between endopeptides and exopeptides?

Answer 4

Proteolytic peptidases that break peptide bonds

Endopeptides = Peptide bonds within the molecule (Trypisin, chymotrypsin & elastase)

Exopeptides = Which breaks the peptide bonds from their end molecules

Question 5

Where are the following enzymes from or found?

a) Carboxypeptidase
b) Aminopeptidase

Answer 5

a) Carboxypeptidase = From the pancreas

b) Aminopeptidase = On luminal membrane

Question 6

Amino acids are transported across the basolateral membrane into the interstital fluid via facilitated diffusion

Answer 6

Energy from the Na+/K+ATPase pumps on the basolateral membrane

Question 7

Glycogen is a polymer of glucose molecules linked by..

a) α1-4 glycosidic linkages
b) ß1-4 glycosidic linkages
c) α1-6 glycosidic linkages
d) ß1-4 glycosidic linkages

Answer 7

Glycogen is a glucose polymer linked by α1-4 glycosidic linkages

It has some α1-6 linkages for branches

Question 8

Which of the following is correct when applied to ptyalin?

a) It is a minor form of amylase in humans
b) It acts in the jejenum and ilium
c) It has an optimum pH of 8.2
d) It is a saliva α-Amylase

Answer 8

Ptyalin = saliva α-Amylase

• Acts in the mouth
• The major form of alpha amylase in humans
• Optimum pH = 6.7

Question 9

Why does a hight concentration of Na+ at the intestinal mucosa facilitate absorption?

Answer 9

Glucose and Na+ share a transporter. Allows more glucose to be absorbed.