Question

Why does the tubular fluid in nephrons need to be buffered?

A) to allow for tubular modification of fluids
B) to prevent edema
C) to prevent increasing respiratory rate
D) to maintain pH gradient

Answer 1

The tubular fluid in nephrons is buffered to maintain the pH gradient and ensure a stable environment for urine formation, which is essential for acid-base homeostasis and maintaining electrolyte balance.

Step-by-step explanation:

The tubular fluid in nephrons needs to be buffered to maintain the pH gradient. This is crucial as the kidneys play a principal role in acid-base homeostasis by regulating the concentration of hydrogen ions (H+) and bicarbonate (HCO3-) in the body. Buffers like proteins, bicarbonate, and ammonia help resist changes in pH and allow the kidneys to absorb or release H+ ions as needed. Specifically, the proximal convoluted tubule (PCT) secretes H+ into the forming urine for Na+ reabsorption, increasing blood pH. In the collecting ducts, intercalated cells further secrete H+ to remove excess acids from the body.

By retaining a stable pH, the nephrons ensure a conducive environment for the various transport processes essential in urine formation, such as reabsorption and secretion of different solutes. Such processes are vital for maintaining electrolyte balance, regulating blood pressure, and removing waste products efficiently.