101. Artificial Kidney

yaboiemil's version from 2016-02-03 22:43



1. Renal Failure is when the Kidneys stop functioning.
2. Haemodialyser substitutes the kidneys. There are 3 basic parts:


Question Answer
Patient's Extracorporeal Blood CirculationRotary Pumps which circulate blood
DialyserSemipermeable Cellophane Membrane which separates Dialyser Solution from Blood.
Dialysate CircuitPreps and controls flow, maintains patient pH.


3. The cellophane membrane is often arranges in layers or tubes to maximize the surface area.
4. Blood and dialyser are always separate, but small solutes can permeate the membrane.
5. The dialysate travels quicker than the blood in its section, in the OPPOSITE DIRECTION.
6. This ensures that the concentration gradient is high, to allow quick diffusion.
7. The dialysate must have the same pH and concentration as the blood though.

Peritoneal Dialysis

8. Peritoneal Dialysis is accomplished by the implantation of sterile catheters into the
peritoneal cavity.
9. Sterile solution is them pumped into the peritoneal cavity, which behaves as a semipermeable
membrane. This allows some of the toxic solutes to be exchanged via the concentration
gradient. After a few hours, the fluid is drained.


10. Blood is pumped at a special semi-permeable membrane. Only fluid crosses.
11. It is pumped at the membrane with such force that it drags some solute ions across with it.
12. The blood remains behind the membrane. The fluid lost is then replace with identical
fluid, artificially mixed to have the same ion concentration and pH.