Questions: What types of transport are utilized during glucose reabsorption and where do they occur?

During glucose reabsorption in the kidneys, two main types of transport are utilized: active transport and facilitated diffusion.

1. Active Transport: This occurs in the proximal convoluted tubule of the nephron. Glucose is reabsorbed from the filtrate in the nephron into the cells lining the tubule through a process called secondary active transport. This involves sodium-glucose co-transporters (SGLT), which use the sodium gradient established by the sodium-potassium pump (primary active transport) to move glucose against its concentration gradient into the cells.

2. Facilitated Diffusion: Once inside the tubular cells, glucose is transported into the interstitial fluid and then into the bloodstream via facilitated diffusion. This process uses glucose transporters (GLUT) that allow glucose to move down its concentration gradient out of the cells.

In summary, glucose reabsorption in the kidneys involves secondary active transport via sodium-glucose co-transporters in the proximal convoluted tubule, followed by facilitated diffusion through glucose transporters into the bloodstream.