During hemodialysis, what occurs?

• A. Blood filtered through a dialyzer
• B. Blood filtered through a peritoneal membrane
• C. Blood removed and stored, then reinjected
• D. Oxygenation occurs

Answer: (A)

During hemodialysis, blood is circulated outside the body through a dialyzer, an artificial kidney. Inside the dialyzer, blood flows on one side of a semipermeable membrane while dialysate flows on the other. Waste products (like urea and creatinine) and excess fluids diffuse across the membrane into the dialysate and are removed, effectively filtering the blood. This separation and removal of wastes is what defines the process.

Using a peritoneal membrane describes peritoneal dialysis, not hemodialysis. Blood being removed and stored then reinjected is not how hemodialysis operates—blood is continuously circulated through the machine. Oxygenation is unrelated to dialysis; it occurs in the lungs.