Question

Which of the following steps, is the correct order of tubular reabsorption?

• A. Potassium ions from the interstitium of the kidneys move into the tubular cells, pushing 3 sodium ions out of the tubular cells and into the interstitium.
• B. Na-Clcotransporter moves a chloride along with a sodium ion, along the sodium gradient. These transporters are basically found in the PCT and DCT.
• C. Water molecule moves passively across the tubules in all the regions where the tubules are permeable to water.
• D. The brush border cells engulf protein in a vesicle, which is digested in the tubular cells. The resulting product of amino acids is then released into the interstitium from which it is absorbed into the blood vessels.
• E. Specific carriers are present in the basolateral as well as the apical membrane, which utilize ATP to transport certain substances, largely, drugs and organic acids from the blood and into the tubular fluid, against their concentration gradients.

Answer 1

The correct option is C Water molecule moves passively across the tubules in all the regions where the tubules are permeable to water.

To be reabsorbed (moved from the filtrate to the plasma), a substance must traverse five distinct barriers. They are 1. Luminal cell membrane, 2. Cytosol, 3. Basolateral cell membrane, 4. Interstitial fluid, 5. Capillary wall