The basic functional unit of the kidney is the nephron. Each nephron consists of several parts: the glomerulus, which filters blood; the proximal tubule; the loop of Henle; and the distal convoluted tubule. Nephrons are critical for regulating water and electrolyte balance, as well as for removing waste products from the bloodstream. A healthy kidney contains about a million nephrons that work collaboratively to maintain fluid homeostasis.