Digestion and Absoprtion - Prunuske

Question 1

What kind of a transporter is SGLT-1?

What is being transported?

Answer 1

SGLT-1 is a monosaccharide symptorter.
2 Na and either glucose or galactose are moved
(Dependent on gradient produced by Na/K ATPase)

Question 2

Which transporter uses facilitated transport to uptake fructose?

Answer 2

GLUT-5

Question 3

Chymotripsinogen, Procarboxypeptidase, Procolipase, and Prophospholipase all must be activated to do any good.

Which enzyme activates all of these?
How is this enzyme itself activated?

Answer 3

Trypsin activates them!

Must be converted from trypsinogen by enteropeptidase on the brush border

Question 4

What is the source of power pulling Amino Acids across the apical membrane of the intestine?

Answer 4

They are brought across by Na-dependent symporters.

This means they rely on basolateral Na/K pump for the power

Question 5

How are peptides absorbed across the apical membrane of the intestine?

Answer 5

The PEPT-1 transporter co-transports peptides with protons

Protons are supplied by the Na/H exchanger on the apical side.
The Na/H exchanger is supported by the Na/K ATPase on the basolateral side.

Wow!

Question 6

How does my 5-month old niece transport proteins across her intestine as compared to yours?

Answer 6

For the first 6 months, intact proteins are actually absorbed through endocytosis!

This is how passive immunity occurs in infants

Question 7

Ezetimibe:
What is the function?
Mechanism?

Answer 7

Function: Tx for patients with hypercholesterolemia
Mech: Reduces uptake of cholesterol from lumen by inhibiting NPC1L1 (an important transporter)

Question 8

Review: What cells secrete Intrinsic factor?

What happens if those cells were to stop secreting intrinsic factor?

Answer 8

Parietal cells

Would result in megaloblastic anemia due to b12 deficiency (specifically pernicious anemia if caused by autoimmune rxn)

B12 deficiency can be caused by metformin use, or ileal resection

Question 9

List a couple things that could cause steatorrhea:

Answer 9

Poor lipid digestion and absorption will do it. Here are some possibiltiies:

• Colipase/Lipase Deficiency (rare)
• Zollinger-Ellison (Excess H+ inactivaes pancreatic lipase)
• Liver Dysfunction (Inadequate bile salts)
• Ileum absorption problems (Bile salt not recycles)
• Bad Chylomicrons (Abetalipoproteinemia)
• Abnormal Lymphatic Transport
• Lack of time in bowel (not enough time to digest/absorb)