The functional unit of the kidney, the structure that does the work, is the

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

Answer: (D)

The nephron is the structure that does the kidney’s work. It handles filtration, reabsorption, and secretion to form urine. The glomerulus inside the nephron is the filtration site, but it’s the entire nephron—the combination of filtering glomerulus and the tubule where reabsorption and secretion occur—that carries out the complete processing of blood into urine. The renal pelvis merely collects urine from many nephrons, and the renal capsule is the kidney’s protective covering. So, the working unit of the kidney is the nephron.