One of the kidneys' main jobs is to remove impurities like please choose white cells urea urine sweat from the blood. This happens in tiny structures called please choose nephrons sphincters blood vessels glands . These have a renal please choose stone sphincter medulla capsule , which is in the kidney's cortex and a renal tubule, which is in the please choose bladder medulla artery vein .

The blood passes into a network of capillary vessels called the please choose medulla ureter glomerulus bladder where water, glucose, salts and the impurities are forced through the capillary wall into the tubule. Proteins and blood cells don't pass through because they are please choose insoluble too big too small the wrong shape . All of the glucose and most of the water and salts are re-absorbed back into the blood in the tubule, whilst the impurities are carried away to the bladder.

B. Look at the diagram below. Its labels are missing. Put the correct label in each box. Use lower case letters and be careful with you spelling. (Hint, the third and fourth boxes are each two words).