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Describe how excretion takes place in mammalian kidneys.

Answer Text:
-Blood reaches the kidney from the renal artery, a branch of dorsa aorta and enters the kidney. It then branches into afferent arteriole then into capillaries forming glomerulus in the
-Bowman’s capsule. Blood vessels leaving the capsule or efferent arteriole are narrower than those entering it, causing high pressure to develop in the
glomeruli. High pressure causes plasma and substances of low molecular weight to be filtered out out of the capsule to form glomerular filtrate, a process called ultrafiltration.
-The filtrate containing substances like urea, glucose, amino acids flows into the proximal convulated tubule, where selective reabsorption of all
glucose, all amino acids are absorbed by active transport, some water and vitamins occur in the blood.The filtrate flows to loop of Henle where some
salts are reabsorbed into the blood.
-The filtrate containing urea flows into the distal convulated tubule, where the remaining useful substances(e.g.salts and water) are reabsorbed by osmosis. The filtrate passes into the collecting tubule where more reabsorption of water takes place. Excess water, urea and salts, now called urine, flows into the collecting duct and are removed through the ureter