The functional unit of the kidney is called the:

• A. Glomerulus
• B. Ureter
• C. Renal pelvis
• D. Nephron

Answer: (D)

The main idea is that the kidney’s function is carried out by the nephron, the basic unit that forms urine. Each nephron begins with a filtering component—the glomerulus inside Bowman's capsule—and continues through a tubular system (proximal tubule, loop of Henle, distal tubule, and collecting duct) where water and solutes are reabsorbed or secreted to create the final urine. The glomerulus alone handles filtration, but it’s part of the larger nephron structure that completes urine formation; the renal pelvis is simply a collecting region inside the kidney, and the ureter transports urine to the bladder. Therefore, the nephron is the functional unit of the kidney.