How many nephrons are approximately found in a human kidney?

A human kidney typically contains approximately 1 million nephrons. Nephrons are the functional units of the kidney, responsible for filtering blood, excreting waste, and regulating water and electrolyte balance. Each nephron consists of a glomerulus for filtration and a tubule for reabsorption and secretion of substances.

Understanding that the number is around 1 million helps to grasp the vast capacity of the kidneys to manage bodily functions, given that each nephron plays a crucial role in urine formation and overall homeostasis. This approximate count also reflects the complexity and efficiency of the kidney's structure, enabling it to effectively maintain the body’s fluid and electrolyte balance, even under varying conditions and dietary influences. The estimates of nephrons in the other options are inaccurate, as they either underestimate or overestimate the actual average number typically found in healthy human kidneys.