Question

The movement of glucose across the apical plasma membrane of epithelial cells (against a concentration gradient) occurs by cotransport with ____________ ions.

Answer 1

Glucose moves across the apical plasma membrane of epithelial cells through cotransport with sodium ions.

Step-by-step explanation:

The movement of glucose across the apical plasma membrane of epithelial cells (against a concentration gradient) occurs by cotransport with sodium ions. Sodium ions move down their electrochemical gradient into the cell from the tubular lumen, and a Na+/glucose symport protein assists both sodium and glucose movement into the cell.

The cotransporter moves glucose into the cell against its concentration gradient as sodium moves down the electrochemical gradient created by the basal membranes Na+/K+ ATPases. The glucose molecule then diffuses across the basal membrane by facilitated diffusion into the interstitial space and from there into peritubular capillaries.