What is the primary function of nephrons in the kidneys?

The primary function of nephrons in the kidneys is to filter and reabsorb substances from the blood. Nephrons are the basic structural and functional units of the kidney, and there are approximately one million of them in each kidney. Their key roles include filtering the blood to remove waste products and excess substances, while also reabsorbing essential nutrients, electrolytes, and water back into the bloodstream. This filtration process is crucial for maintaining the body's homeostasis, regulating fluid balance, and ensuring that waste is adequately excreted through urine.

The filtration process begins at the glomerulus, where blood plasma is filtered, and then the filtered fluid, known as filtrate, passes through various segments of the nephron. In these segments, reabsorption takes place, allowing the body to reclaim valuable substances like glucose and certain ions. The result is the production of urine, which contains waste and excess substances, while the reabsorbed materials enter the bloodstream to be reused by the body. This effective filtration and reabsorption system showcases the essential role nephrons play in kidney function and overall metabolic balance.