Glucose and galactose gain access to enterocytes via which transporter?

• A. GIP
• B. Glucokinase
• C. Enterokinase
• D. SGLT-1

Answer: (D)

Glucose and galactose enterocytes are taken up at the luminal surface by a sodium-dependent transporter that co-transports Na+ with the sugars. This transporter, located on the apical membrane, uses the sodium gradient (set byNa+/K+-ATPase on the basolateral side) to move glucose and galactose into the cell. Once inside, these sugars exit across the basolateral membrane into the blood via facilitated diffusion through transporters like GLUT2. Fructose, by contrast, uses a different route (GLUT5) and is not Na+-dependent.

The other options aren’t transport mechanisms for luminal glucose or galactose: one is a hormone that stimulates insulin release, another is an enzyme that phosphorylates glucose inside cells, and the last is an enzyme that activates digestive proteases.