Normal intestinal absorption of glucose depends on:
A glucagon.
B sodium.
C Glut-4 transporters.
D GLP-1.
E insulin.
The correct answer and explanation is:
The correct answer is B. sodium.
Explanation:
Normal intestinal absorption of glucose relies on a process known as active transport, which requires the movement of glucose across the intestinal epithelial cells into the bloodstream. This process involves the sodium-glucose linked transporter 1 (SGLT1), which uses sodium to facilitate glucose absorption.
- Sodium’s Role:
The absorption of glucose in the intestines is coupled with the transport of sodium ions. SGLT1, which is located on the apical membrane of enterocytes (intestinal cells), uses the concentration gradient of sodium across the cell membrane to actively transport glucose against its concentration gradient. Sodium is actively pumped out of the enterocyte into the bloodstream by the Na+/K+ ATPase pump, creating a low intracellular sodium concentration. This allows sodium to enter the cell, along with glucose, through the SGLT1 transporter. - Other Factors (not directly involved in absorption):
- Glucagon (A): Glucagon primarily regulates glucose release from the liver into the bloodstream, not glucose absorption from the intestines.
- GLUT-4 (C): GLUT-4 is a glucose transporter primarily found in muscle and adipose tissues. While it is involved in glucose uptake, it does not play a role in the intestinal absorption of glucose.
- GLP-1 (D): Glucagon-like peptide-1 (GLP-1) enhances insulin secretion and inhibits glucagon release, but it does not directly influence glucose absorption in the intestine.
- Insulin (E): Insulin helps regulate glucose uptake by tissues like muscle and adipose, but it is not directly involved in the absorption of glucose from the intestines.
Thus, sodium is the key factor driving glucose absorption in the intestine via the SGLT1 transporter, making it the correct answer.