How does filteration occur in the kidney?

Inside the kidneys there are millions of nephrons which filter the blood. They do this by having blood build up a high pressure in the glomerulus (a ball of capillaries) so that the small molecules (e.g. water, glucose urea and ions) are forced through into the Bowman’s capsule while the blood cells and proteins stay. This mixture is no called glomerial filtrate and has been filtered by ultra filtration. This flows down the first coiled tubule where all the glucose is reabsorbed (using active uptake), as are the required salts. Water is then reabsorbed at the loop of henle, and also at the second coiled tubule. It then heads down the collecting duct into the ureter. This flows down into the bladder. (the urea and excess ions are not absorbed.