Question

Blood clotting requires _____________

Answer 1

Hint: It is a plasma protein and is released at the site of the injury. It converts prothrombin into thrombin which acts as an enzyme. It consists of tissue factor, phospholipids \[CaC{l_2}\]. It was earlier used as a reagent to assay prothrombin time. The other requirement is derived from \[CaC{l_2}\].

Complete answer:
Blood clotting is a process which prevents excessive bleeding during an Injury. In plasma, both platelets and proteins work together to form a clot over the injury. Usually, the human body will dissolve the blood clot after some time of healing. It begins instantly when the endothelium lining the blood vessel gets injured. Platelets form a plug at the site of the injury and it is known as primary hemostasis.
Blood clotting requires calcium ions and thromboplastin. Thromboplastin is a complex enzyme made by the mixture of phospholipids and tissue factor in plasma which converts prothrombin into thrombin. It is released from the platelets at the site of the injury. It is a plasma protein and is the principal enzyme of hemostasis. Calcium ions in this process act as a cofactor. Also, when enclosed to thrombomodulin, protein C is activated, an anticoagulant zymogen.

Note:
Some disorders of blood flow are;
1. Hemorrhage; i.e., simple bleeding or blood loss which may occur internally or externally
2. Bruises i.e., damage to the blood capillaries causing mild localized bleeding which is visible as a dark spot on the external skin, and
3. Thrombosis i.e., formation of a blood clot or coagulation of blood inside the blood vessels (it obstructs the flow of blood and is very dangerous).