Anatomy and Physiology II Practice Test

Which part of the nephron is essential for the regulation of blood pH?

1. Glomerulus

2. Proximal tubule

3. Distal tubule

4. Loop of Henle

The correct answer is: Distal tubule

The correct choice highlights the role of the distal tubule in regulating blood pH, an essential function of kidney nephron physiology. The distal tubule, particularly through its cells, performs key processes that contribute to acid-base balance in the body. This part of the nephron actively secretes hydrogen ions (H+) into the tubular fluid while reabsorbing bicarbonate ions (HCO3-). By managing these substances, the distal tubule can effectively influence the acidity or alkalinity of the blood, thus maintaining homeostasis. When the body is in an acidotic state, the distal tubule increases hydrogen ion secretion, helping to raise blood pH back to normal levels. Conversely, during alkalosis, it can reduce hydrogen ion secretion and enhance bicarbonate reabsorption, thus lowering blood pH. In comparison, the glomerulus is primarily involved in the filtration of blood, the proximal tubule reabsorbs a significant portion of filtered water and solutes, and the Loop of Henle concentrates urine but does not directly regulate acid-base status. Each of these structures has distinct functions but does not play a central role in the delicate balance of blood pH like the distal tubule does.