RRB Group D 9-Nov-2014 Shift 1 Solved Paper

(1) Clotting requires calcium ions $\left(\mathit{C}{\mathit{a}}^{2+}\right)$ (which is why blood banks use a chelating agent to bind the calcium in donated blood so the blood will not clot in the bag). Blood clotting occurs at the point of injury to control bleeding from blood vessels. The coagulation of the blood is initiated by the blood platelets. Calcium ions are required for the promotion or acceleration of blood clotting pathways. The clotting cascade occurs through two separate pathways that interact—intrinsic pathway and extrinsic pathway.