Question

Assertion: Nitrogenous wastes move from blood to dialysis fluid
Reason: Anti-coagulant like heparin is added to drained blood before dialysis

• A. Both assertion and reason are true and reason correctly explains assertion
• B. Both assertion and reason are true but reason does not correctly explain assertion
• C. Assertion is true but reason is false
• D. Both assertion and reason are false

Answer 1

The correct option is B Both assertion and reason are true but reason does not correctly explain assertion

If the kidneys are not working properly, then the nitrogenous wastes of our body (urea) get accumulated in the blood. This condition is called uremia. In uremic patients, nitrogenous wastes can be removed from their body using the process of hemodialysis. In this process, blood is drained from a suitable artery and mixed with an anticoagulant (heparin) in order to prevent the blood from clotting. It is then pumped into the dialysing unit which contains a coiled tube made of porous cellophane membrane and a surrounding dialysing fluid. The dialysing fluid, whose composition is similar to that of the plasma, but does not contain the nitrogenous wastes. As the unfiltered blood carrying the nitrogenous wastes flows through this cellophane tube, the nitrogenous wastes (urea) diffuse into the dialysing fluid from the porous cellophane membrane of the tube. This happens because of the concentration gradient created by the dialysing fluid (which does not contain urea) and the blood (where urea is present in high concentration). This concentration gradient helps the nitrogenous wastes to easily diffuse out into the surrounding fluid from the blood thereby filtering the blood. After adding anti-heparin, the now filtered blood is pumped back into the body of the individual through a suitable vein.