A nephron is the basic functional unit of the kidney, responsible for filtering blood and producing urine. Each kidney contains about a million nephrons, which work together to remove waste and excess substances from the body. The nephron consists of several parts, including the glomerulus, where blood filtration begins, and the renal tubule, where essential nutrients and water are reabsorbed. As blood flows through the nephron, it undergoes a complex process of filtration, reabsorption, and secretion. This process helps maintain the body's balance of electrolytes, water, and pH, ensuring that essential substances are retained while waste products are excreted.