B3 Topic 1 The Kidneys

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  • Created by: Hannah
  • Created on: 06-05-13 07:32

The kidney has three main roles: 

  • adjustment of ion level
  • adjustment of water content 
  • removal of urea which is produced by the break down of excess amino acids in the liver. 

Ultra filtration: A high pressure pushes water, urea, ion and glucose out of the blood ad into the Bowmen's Capsule. The glomerulus and the Bowmen capsules acts like a filter where big molecules such as protein and blood cells aren't pushed back and stay in the blood. 

Re absorption: As the liquid flows through the nephron: glucose is selectively reabsorbed and it moves in and out of the blood and the nephron against a concentration gradient. Water is reabsorbed according to the level of ADH. 

Release of waste: Urea and excess water are not reabsorbed. They continue out of the nephron to the ureter to the bladder as urine. Urine is released through the uretha. 

The amount of water reabsorbed in according to the ADH. The brain monitors the water content of the blood and tells the pituitary gland to release ADH into the blood based on how much is needed. This is controlled by a mechanism called negative feedback. This is when a change in environment triggers a response…


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