Question

Blood platelets helps in the blood coagulation mechanism by liberation of
(a) Thromboplastin
(b) Thrombin
(c) Prothrombin
(d) None of the above

Answer 1

Hint: Thrombocytes which are also known as blood platelets are non-nucleated. Platelets form in bone marrow, and the formation of platelets is known as thrombopoiesis.

Complete answer:
The mechanism to prevent excessive blood loss from the body is called blood clotting. When an injury from blood platelets start to release platelet thromboplastin with lipoprotein factor thromboplastin. Both these thromboplastins combine with calcium and form prothrombinase. Prothrombinase inactivates heparin in presence of calcium, and prothrombinase also converts prothrombin into thrombin. Thrombin first depolymerizes fibrinogen and then forms fibrin by repolymerization. The long and solid fibers of fibrin form a dense network and form clot with the help of blood corpuscles and platelets.
After injury clotting takes place in between 2-5 minutes, and after clotting serum form.
Vitamin K is important for clot formation, which synthesizes prothrombin in the liver.

Additional Information: Macfarlane has given the theory of blood coagulation. 13 factors are responsible for blood clotting which are present in cascade form. These factors work on the basis of their activation.
The factor I is Fibrinogen
Factor II is Prothrombin
Factor III is Thromboplastin
Factor IV is Calcium
Factor V is Proaccelerin, Accelerator globulin
Factor VI is the activation product of factor V that's why it is a hypothetical factor
Factor VII is Proconvertin
Factor VIII is an Antihemophilic factor
Factor IX is Christmas factor, Antihemophilic factor B
Factor X is Stuart power factor
Factor XI is Plasma thromboplastin antecedent, Antihemophilic factor C
Factor XII is Hageman factor
Factor XIII is Fibrin stabilizing factor
So, the correct answer is Thromboplastin.

Note: In lymph red blood corpuscles and platelets are absent. Lymph only consists of plasma and white blood corpuscles, lymph helps in the exchange of nutrients and gases between cells, it also balances blood volume.