What is the functional unit of the kidney and where are they located?

• A. Nephron – Cortex
• B. Nephron – Medulla
• C. Glomerulus – Cortex
• D. Collecting Duct – Cortex

Answer: (A)

The functional unit of the kidney is the nephron. It carries out filtration, reabsorption, and secretion to form urine. Nephrons are located mainly in the renal cortex, where the glomerulus sits within Bowman's capsule and most of the tubular segments (proximal and distal tubules) reside. Some nephrons, specifically juxtamedullary ones, have long loops of Henle that reach into the outer medulla, and collecting ducts run through the medulla, but the bulk of the nephron’s structure is in the cortex. This is why nephron paired with cortex is the best answer.