Due to the renal failures the blood urea level increases abnormally . in such a situation an artificial kidney is used for removing excess urea from the blood . this process in known as hemodialysis. For this the blood is taken from the artery , then it is cooled to 0 degree celcius . after this the blood is mixed with anticoagulats like heparin to prevent the coagulation of blood. and then pumped into artificial kidney. The artificial kidney have number of tubes and membranes. This membrane is a semi permible membrane , which does’t allow the macromolecules to pass through it . the fluid in the tubes have some nitrogenous waste products , namely urea, uric acid etc . these smaller components are separated by dialysis .  the blood coming out from this apparatus is then heated upto body temperature . then mixed with antiheparin and return back to the vein of the body. After mixing of antiheparin the blood regains its original coagulation power.  Hemodialysis saves lifes of number of uremic patients.Hemodialysis Process