What is the functional unit of the kidney called?

The functional unit of the kidney is called the nephron. Each kidney contains about a million nephrons, which are responsible for filtering blood, regulating fluid balance, and excreting waste products through urine. The nephron consists of several parts, including the glomerulus and renal tubules.

The glomerulus, while important, is just one component of the nephron that plays a crucial role in filtration. The ureter is a tube that carries urine from the kidneys to the bladder, and nephrectomy refers to the surgical removal of a kidney. Thus, "nephron" is the correct answer, as it encompasses the entire functional structure necessary for the kidney's role in homeostasis and waste management.