Explain how this system maximizes glucose absorption from the intestinal lumen into the epithelial cells and from the epithelial cells into the blood.

Question

Nina Shannon

Biology

8 October, 18:21

Explain how this system maximizes glucose absorption from the intestinal lumen into the epithelial cells and from the epithelial cells into the blood.

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Answers (1)

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Gordon Snyder · Answer 1

Transport of glucose from the intestinal lumen into the blood. Activity of the Na+/K + ATPase (green) in the basolateral surface membrane generates Na + and K + concentration gradients, and the K + gradient generates an inside-negative membrane potential.

Explanation:

The Na+K + ATPase uses the energy of ATP hydrolysis to move Na + out of the epithelial cells lining the intestine and into the blood. The reduced concentration of Na + inside the cell coupled with high Na + inside the lumen of the intestine results in a driving force for the movement of Na + into the cell.

The cotransporters in the membrane of the epithelial cell facing the intestine allow Na + to enter only when accompanied by either glucose or one of the amino acids (each have their own set of co-transporters).

Glucose then moves into the blood through the permease in the membrane between the cell and the blood. Thus, ATP is used as an energy source to drive Na + out of the cell, resulting in glucose transport from the intestine to the blood.