Hemodialysis.

(a) This young patient is undergoing hemodialysis. A shunt was placed in his upper arm where the arteries and veins are larger. It was placed in his left arm because he is right handed. (b) During dialysis he is able to color and read to pass the time while his blood is cleansed of wastes. His blood pressure is checked frequently during dialysis and so the blood pressure cuff is allowed to remain on his right upper arm. (c) The dialysis machine pumps the blood through tubing whose wall is a selectively permeable membrane. Dialysate fluid surrounds the tubing. Wastes and excess amounts of electrolytes and glucose move from an area of higher concentration (in the blood) to an area of lower concentration (dialysate fluid). The blood is pumped back through an arteriovenous (AV) fistula or shunt.