Question

Intrinsic and extrinsic pathways of blood clotting are interlinked at the activation steps of which of the following factors?
A. Factor IX
B. Factor IV
C. Factor X
D. Both A and C

Answer 1

Hint:-Blood is an important body fluid which is responsible to carry the respiratory gases and other nutrients and hormones to different parts of the body. The blood contains special proteins that work together in case of injury to stop bleeding. Various processes are carried out as a response to bleeding and results in less blood to leak out and clotting occurs.

Complete step-by-step solution:-
Blood clotting or coagulation is the mechanism through which blood in its liquid state is converted to a gel like structure at the point of a damaged vessel .this process forms a blood clot and reduces the loss of blood from the site of injury .this process is followed by the repair mechanism .Blood contains various types of proteins and platelets which are involved in the mechanism of coagulation .In addition to the platelets blood also contains various factors which help in this process.
The process of coagulation begins at the site of the injury due to the damage in the endothelial lining of the blood vessel. This change initiates two processes which are changes in the platelet’s and exposure of sub endothelial tissue factor to plasma factor. Platelets form a plug like structure.
The blood clotting factors activate each other through a series of reactions known as the clotting cascade to produce fibrin. Fibrin is a non-soluble plasma protein and it sticks together to form a clot. The process of cascade formation occurs by two separate pathways which are intrinsic and extrinsic pathways.
The extrinsic pathway is activated by the trauma and it causes the blood to release from the vascular system. This pathway is more quick in action and involves the factor VII. The intrinsic is captivated by both trauma as well as by the platelets, exposed endothelium, chemicals or collagen. It is an important pathway and is much slower than the extrinsic pathway. It involves factors VIII, IX, XI, XII. A third type of pathway is formed when the both types of pathways meet and conclude the blood coagulation pathway. This is known as the common pathway and includes factors I, II, V and X. The common pathway both the intrinsic as well as the extrinsic pathways are interlinked and it begins by the activation of the factor X. The factor X is converted into Xa. It is caused by factor IX of the intrinsic pathway and tissue factors of the extrinsic pathway. Factor X acts to cleave prothrombin to produce active thrombin and further thrombin converts soluble fibrinogen into insoluble fibrin clot.
Therefore, the correct option is option C.

Note:- The blood coagulating is brought about by the platelets and the blood clotting factors. THe process or mechanism of clot formation is known as cascade of clotting and consists of two pathways which are the intrinsic and the extrinsic pathways. Both the pathways meet to activate the factor X in the common pathway. THe factor X then through a series of reactions convert fibrinogen into fibrin to form a clot.