Each of these organs contains about 1 million nephrons, which filter blood
The blood 
passes... [DOC] [TLE] Urinary Kidney - Learn Skeleton System Anatomy - Visible Body [PAR] These organs are constantly at work: Nephrons, tiny structures in the renal 
pyramids, filter ... Nephrons: The Basic Functional Units of Blood Filtration and 
Urine Production ... Each kidney contains over 1 million tiny structures called 
nephrons.