Name the functional units of the kidney.

• A. Nephrons
• B. Glomeruli
• C. Renal pyramids
• D. Collecting ducts

Answer: (A)

The nephron is the kidney’s functional unit. It carries out filtration, reabsorption, secretion, and urine concentration. Each nephron includes a renal corpuscle (the glomerulus and Bowman's capsule) where blood is filtered, plus a renal tubule (proximal tubule, loop of Henle, distal tubule, and collecting duct) where the filtrate is modified as it moves along. The glomerulus does the filtration step, but it’s part of the nephron, not the whole unit. Collecting ducts handle final urine concentration and drainage, but they’re components of the nephron as well. Renal pyramids are larger structural regions containing many nephrons and ducts, not the functional unit itself.