Question

Thromboplastin is secreted by
A. Platelets
B. Lymphokines
C. Helper T cells
D. Mast cells

Answer 1

Hint: To derive the correct answer, you must first know the function of thromboplastin. Thromboplastin is a plasma protein. Its main function is that it helps in the blood clotting process. Can you guess the most important blood component that helps in the clotting of blood? By doing so, you will be able to derive the correct answer.

Complete answer:
Blood coagulation or clotting of blood is an important process where blood clots to stop bleeding when a blood vessel is injured.A series of steps occurs so that blood clotting occurs effectively. It must be mentioned that clotting of blood must be balanced. When excessive clotting occurs, it stops blood supply to necessary organs. When very little clotting occurs, there may be a huge amount of blood loss leading to fatal consequences. The process of blood coagulation occurs in steps.
1. There occurs an injury in the blood vessel leading to blood loss.
2. The smooth muscle fibers present in the walls of the injured blood vessel cause constriction of the injured blood vessel so that it leads to reduced blood loss.
3. Platelets are activated due to release of certain chemicals from the injury site and these platelets stick to one another and also cause other platelets in the vicinity to become sticky
Thromboplastin is secreted by the platelets that catalyze the reaction which converts prothrombin into thrombin which is an important step in the blood coagulation process.

Thus, the correct option is A Platelets.

Note:
Platelets are formed by the process of fragmentation from megakaryocytes. The cells found in blood are formed in the bone marrow of long bones by the process of hematopoiesis where there are different precursors for different cell types that ultimately lead to the formation of red blood cells, white blood cells and platelets.