Final answer:
Normal saline is used to remove urea and waste products from the extracorporeal circuit during hemodialysis.
Step-by-step explanation:
Normal saline is used to remove urea and other waste products from the extracorporeal circuit during hemodialysis. Hemodialysis is a process used to extract urea and waste products from the blood when the kidneys fail to remove them. In a hemodialysis system, the blood flows through cellophane tubes placed in an isotonic solution containing NaCl, KCl, NaHCO3, and glucose. The cellophane membrane selectively allows urea and other waste products to be removed while preventing proteins, large molecules, and blood from passing through.