Did you know that the kidneys of an average adult human being filter about 180 L of plasma every day! That is every day, the entire volume of plasma is filtered about 50 times by the kidneys! This massive amount of filtration is indeed necessary to allow the kidneys to eliminate waste products present in the plasma. Most of these waste materials are the byproducts of normal metabolism. They are removed from the plasma through filtration (and secretion for some) in the kidneys and ultimately are eliminated from the body through urine. However, a significant amount (in fact most) of the filtered water must be reabsorbed in order to prevent life-threatening dehydration. Test your basic knowledge of kidney filtration and reabsorption by taking this simple quiz.