Nephrons are the basic functional units of the kidneys, responsible for filtering blood and producing urine. Each kidney contains about one million nephrons, which consist of a glomerulus and a tubule. The glomerulus filters blood, while the tubule reabsorbs essential substances and secretes waste. These tiny structures play a crucial role in maintaining the body's fluid and electrolyte balance. By regulating the levels of sodium, potassium, and water, nephrons help control blood pressure and ensure that harmful substances are excreted efficiently. Proper nephron function is vital for overall kidney health.