The nephron is the term used to refer to the basic structural and functional unit of the kidney. Each kidney contains millions of nephrons, which are responsible for filtering waste products and excess fluid from the blood and producing urine. The nephron consists of several structures, including the glomerulus, Bowman's capsule, proximal and distal tubules, and collecting ducts. The glomerulus filters the blood, and the filtrate then passes through the tubules, where various substances are reabsorbed or secreted depending on the body's needs. The resulting urine is then transported to the bladder for excretion.