What are the functional units of the kidney?

Ureters are tubes that transport urine from the kidneys to the bladder but do not perform any filtering or functional activities related to urine formation. They are important for the excretion process but are not considered functional units of the kidney itself.

Glomeruli are clusters of capillaries located within nephrons that facilitate the filtration of blood, but they are not complete functional units on their own. Instead, they are part of the nephron and contribute to its overall function in filtering waste from the blood.

Renal capsules refer to the protective outer layer surrounding the kidneys. While they play a role in protecting kidney tissue, they do not participate in the functional processes of filtration, reabsorption, or secretion, which are essential to kidney function.