The blood is basically cleaned up in the kidneys – waste is removed to be excreted in the urine and the mineral and ion balance is corrected.
Blood passes into capillaries of a structure called the glomerulus as the first step. The walls of the capillaries act as filters so that the larger items in the blood – red and white cells and platelets – do not pass through. Water, dissolved salts, sugar and urea (waste from protein usage) all get through and then flow through a series of small tubes, or tubules.
Various things are taken in and out during the blood's transit through these tubules. Water and dissolved salts are reabsorbed, as is the sugar. Small amounts of salt and urea pass through to the collecting duct, which then leads out of the kidney. The solution that exits the kidney is urine and it passes along the ureter to the bladder and from there, it leaves the body.
Blood passes into capillaries of a structure called the glomerulus as the first step. The walls of the capillaries act as filters so that the larger items in the blood – red and white cells and platelets – do not pass through. Water, dissolved salts, sugar and urea (waste from protein usage) all get through and then flow through a series of small tubes, or tubules.
Various things are taken in and out during the blood's transit through these tubules. Water and dissolved salts are reabsorbed, as is the sugar. Small amounts of salt and urea pass through to the collecting duct, which then leads out of the kidney. The solution that exits the kidney is urine and it passes along the ureter to the bladder and from there, it leaves the body.