B3 3.3

Biology 3- Keeping internal conditions constant.

Kidneys can be damaged and destroyed by infections, untreated failure of both kidneys can lead to death because toxins (like urea) build up inside the body and the salt and water balance is upset.

Dialysis-an artificial kidney

• A dialysis machine carries out the functions of a kidney, it relies on the process of dialysis to clean the blood.
• Blood leaves the body and flows between partially permeable membranes.
• On the other side of the membrane is dialysis  fluid which contains the same concentration of useful substances as the blood.
• There is no net movement of glucose and mineral ions out of the blood so glucose and mineral ions are not lost.
• The dialysis fluid contains normal plasma layers of mineral ions so any excess ions are removed from the blood.(diffusion)
• Dialysis treatment restores concentrations of dissolved substances to normal levels 
• You can then carry on with a normal life until urea and other substances build up again (repeated at…