Question

Which one of the following is correct with reference to haemodialysis?

• A. It absorbs and resends excess of ions.
• B. The dialysis unit has a coiled semi permeable cellophane tube.
• C. Blood is pumped back through a suitable artery after haemodialysis.
• D. Anti-heparin is added prior to haemodialysis.
• E. Nitrogenous wastes are removed by active transport

Answer 1

The correct option is B The dialysis unit has a coiled semi permeable cellophane tube.

In haemodialysis, blood drained from a convenient artery is pumped into a dialysing unit after adding an anticoagulant like heparin. The unit contains a coiled cellophane tube surrounded by a fluid (dialysing fluid) having the same composition as that of plasma except for the nitrogenous wastes. The porous cellophane membrane of the tube allows the passage of molecules based on concentration gradient. As nitrogenous wastes are absent in the dialysing fluid, these substances freely move out, thereby clearing the blood. The cleared blood is pumped back to the body through a vein after adding anti-heparin to it. Hence option B is the correct answer.