What is the functional unit of the kidney?

The nephron is considered the functional unit of the kidney because it is the smallest structural and functional component responsible for the processes of filtration, reabsorption, and secretion of urine. Each kidney contains approximately one million nephrons, which work together to filter blood, remove waste, and regulate various bodily fluids and electrolyte balance.

Within the nephron, multiple components such as the glomerulus and Bowman's capsule play specific roles, but they are part of the larger nephron structure. The glomerulus is the network of capillaries where blood filtration begins, and Bowman's capsule surrounds the glomerulus to collect the filtrate. The collecting duct, on the other hand, is a passage through which urine flows after being processed by the nephron, but it is not the functional unit itself. This underscores why the nephron, encompassing all these elements and their combined functions, is recognized as the essential unit of kidney function.