Question

Blood clotting requires _________________.

• A. $N{a}^{+}$ and $K^{+}$
• B. $N{a}^{+}$ and prothrombin
• C. $N{a}^{+}$ and thromboplastin
• D. $C{a}^{2+}$ and thromboplastin

Answer 1

Answer: (D)

$C{a}^{2+}$ and thromboplastin

• Thromboplastin or thrombokinase (TPL) is a plasma protein aiding blood coagulation through catalyzing the conversion of prothrombin to thrombin. Thrombin is the principal enzyme of hemostasis. It catalyzes the conversion of fibrinogen to fibrin and activates procoagulant factors V, VIII, XI, and XIII. Additionally, when bound to thrombomodulin, it activates protein C, an anticoagulant zymogen.
• Blood clotting occurs at the point of injury to control bleeding from blood vessels . The platelets produce a substance that combines with calcium ions in the blood to form thromboplastin, which in turn converts the protein prothrombin into thrombin in a complex series of reactions.

So, the correct answer is 'Ca2+ and thromboplastin'.