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# Kidneys Blood from the body picks up waste. It then enters the kidney through the renal artery. The kidney filters urea, excess water, minerals and other waste products from the blood. ## Renal cortex (contain renal corpuscles) ## Renal medulla (contain loops of Henle and tubules) ## Nephron...

# Kidneys Blood from the body picks up waste. It then enters the kidney through the renal artery. The kidney filters urea, excess water, minerals and other waste products from the blood. ## Renal cortex (contain renal corpuscles) ## Renal medulla (contain loops of Henle and tubules) ## Nephron This is a close-up of the tiny parts of the kidney that do the filtering work. ### 1. Filtration: Blood enters a nephron through a capillary and moves to a tangled cluster of capillaries called the glomerulus. The glomerulus is surrounded by a thin walled sac called the Bowman's capsule. It is the pressure in the capillaries — the force from that pressure — that pushes small molecules out of the capillaries and into the Bowman's capsule. Blood cells stay in the capillaries. The filtrate goes down the tubule. ### Renal corpuscle - Bowman's capsule - Glomerulus - Capillaries - Tubule ### 2. Reabsorption: As what has been filtered out moves through the tubule, water and many other substances that are important to the body are reabsorbed through capillary walls into the blood. Much reabsorption occurs in the Loop of Henle. ### 3. Urine Excretion: Once water and other important substances are reclaimed by the blood, the filtrate is called urine. Collecting ducts gather urine and transport it to a ureter. - Vein - Artery - Collecting duct - Loop of Henle - To ureter - Renal artery - Renal vein - Ureter - To the bladder