What is the basic functional unit of the kidney?

The basic functional unit of the kidney is the nephron. Each kidney contains approximately one million nephrons, and these structures are essential for the filtration of blood and the formation of urine. The nephron is composed of several parts, including the glomerulus, renal tubule, and collecting duct, but it is the nephron as a whole that performs the vital functions of excretion and regulation of electrolytes and fluid balance.

The glomerulus is a network of capillaries where the initial filtration of blood occurs, but it does not complete the functions of the kidney alone. The renal tubule processes the filtrate received from the glomerulus, and the collecting duct is involved in additional concentration and dilution of urine, but these components operate within the nephron. Without the nephron serving as the overarching unit, these components would not function cohesively to accomplish the kidney's essential roles.