Question

Match the terms to these definitions:

(Excretion, micturition, hemodialysis, ureotelic, uricotelic, transport maximum, glomerular filtration rate, osmoregulation, renal threshold, nephron, countercurrent system, ultrafiltration)

.......... the removal of waste materials and toxic substances and restoration of normal volume and composition of body fluid by means of an artificial kidney.

Answer 1

Hemodialysis is the removal of waste materials and toxic substances and restoration of normal volume and composition of body fluid by means of an artificial kidney.

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 a 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.