What is the functional unit of the kidney?

The nephron is identified as the functional unit of the kidney because it is the basic structural and functional component that performs the essential tasks of filtering blood, reabsorbing nutrients, and excreting waste. Each kidney contains approximately one million nephrons, and they work together to regulate water and electrolyte balance, acid-base balance, and eliminate waste products from the body.

The nephron is composed of several parts, including the glomerulus and the nephron loop, which play different roles in the overall function of urine formation. The glomerulus is involved in the initial filtration of blood, while the nephron loop is responsible for concentrating urine and regulating electrolyte reabsorption. The renal corpuscle, which includes the glomerulus and Bowman's capsule, is vital for the filtration process but does not encompass all the activities that a nephron performs.

Thus, the nephron represents the complete system that integrates filtration, reabsorption, and excretion, making it the key functional unit of the kidney.