Which option correctly identifies the nephron's role?

Which option correctly identifies the nephron's role?

• A. The nephron stores urine before excretion.
• B. The nephron is a blood vessel that carries urine.
• C. The nephron is the kidney’s functional unit; it regulates bladder contractions.
• D. The nephron is the kidney’s functional unit; it filters blood, forms urine, and regulates fluid/electrolyte balance.

Answer: (D)

The nephron is the kidney’s functional unit that filters the blood to form urine and maintains the body’s fluid and electrolyte balance. Blood is filtered in the glomerulus, where water and small solutes pass into the Bowman's space, and then the filtrate flows through the tubules (proximal tubule, loop of Henle, distal tubule) and collecting ducts. Along these segments, most water and essential solutes are reabsorbed, while additional wastes and ions can be secreted, allowing precise regulation of volume, osmolarity, electrolyte levels (such as sodium, potassium, and bicarbonate), and acid-base balance. Through these coordinated steps, the nephron shapes the final urine concentration and composition. It does not store urine—that’s the bladder—or carry urine in a blood vessel, and it does not directly regulate bladder contractions.

The nephron is the kidney’s functional unit that filters the blood to form urine and maintains the body’s fluid and electrolyte balance. Blood is filtered in the glomerulus, where water and small solutes pass into the Bowman's space, and then the filtrate flows through the tubules (proximal tubule, loop of Henle, distal tubule) and collecting ducts. Along these segments, most water and essential solutes are reabsorbed, while additional wastes and ions can be secreted, allowing precise regulation of volume, osmolarity, electrolyte levels (such as sodium, potassium, and bicarbonate), and acid-base balance. Through these coordinated steps, the nephron shapes the final urine concentration and composition. It does not store urine—that’s the bladder—or carry urine in a blood vessel, and it does not directly regulate bladder contractions.