Question

Fibrin, Platelets, Thromboplastin, Fibrinogen, Thrombin.

Answer 1

Blood coagulation is a process that converts elements of the blood into a gel, forming a blood clot and preventing loss of blood from injured blood vessels, tissues or organs.

(i) Platelets play a key role in blood clotting. Due to injury, platelets from the blood are attracted to the injured surface. The platelets clump together to form an aggregate.

(ii) Following the tissue damage, extrinsic pathway is activated rapidly. Damaged tissue releases a complex of chemicals called thromboplastin or tissue factor which initiates coagulation. This results in the formation of prothrombim activator.

(iii) Prothrombim activates the enzyme thrombin, which converts inactive fibrinogen to soluble threads of fibrin.

Hence the correct order is: Platelets→Thromboplastin→Thrombin→Fibrinogen→Fibrin