What are the glomeruli, or filters, in the kidney?
Each kidney has about 1 million filters, each about the size of a pinhead. The glomerulus consists of a small ball of tiny blood vessels inside a bag, and the bag has a drainage tube running out of it. As blood passes through the glomerulus, some fluid is forced through the walls of the blood vessels, which are very thin and delicate, into the bag, which acts as a collecting space. This fluid then passes along the drainage tubes inside the kidney, which concentrate the waste products by removing excess water, so eventually producing urine. The urine then runs down to a funnel-like area in each kidney, and drains down to the bladder.