<P> The way the kidneys do this is with nephrons . There are over 1 million nephrons in each kidney ; these nephrons act as filters inside the kidneys . The kidneys filter needed materials and waste , the needed materials go back into the bloodstream , and unneeded materials becomes urine and is gotten rid of . </P>
<P> The way the kidneys do this is with nephrons . There are over 1 million nephrons in each kidney ; these nephrons act as filters inside the kidneys . The kidneys filter needed materials and waste , the needed materials go back into the bloodstream , and unneeded materials becomes urine and is gotten rid of . </P>
which structure of the excretory system mainly functions in filtration
which structure of the excretory system mainly functions in filtration
nephrons
nephrons