What do nephrons filter from the bloodstream?

Nephrons are the functional units of the kidneys responsible for filtering the blood. They carry out the essential processes of filtration, reabsorption, and secretion. Throughout this process, nephrons filter various substances from the bloodstream, including waste products, excess salts, and excess water, among others.

While nephrons can indeed process many gallons of fluid daily — approximately 180 liters in total in a healthy adult — they also play a crucial role in regulating the body's electrolyte balance and blood pressure by adjusting the volume of fluid and the concentrations of solutes. This comprehensive filtering capability is what underscores the importance of the nephron in maintaining homeostasis within the body.

The other options are limited in scope; they either refer to specific products that are filtered or are too narrow, which does not capture the full spectrum of nephron function. Therefore, the correct answer highlights the capacity of nephrons to filter large volumes of fluid from the bloodstream, indicating their critical role in kidney function and overall health.