Question

Blood clotting is helped by

• A. ${Na}^{+}$
• B. $K^{+}$
• C. ${Ca}^{2+}$
• D. ${Mg}^{2+}$

Answer 1

Answer: (C)

${Ca}^{2+}$

Clotting is the process by which blood loss from a damaged blood vessel is stopped by changing it from liquid to a gel like substance known as clot. It is a multiple step cascade requiring many co-factors, one of which is calcium. The factors are all present in the circulating blood as inactive precursors, which are activated upon some trigger by the clotting cofactors. Calcium acts as a cofactor to assist other coagulation factors to bind to phospholipids. It helps in platelet aggregation by activating protein kinase C, leading to activation of phospholipase A and leading to clot formation. It has roles in acting as cofactors for coagulation factor 2, 7, 9 and 10. Hence, chelating agents are added to blood donating bags to chelate the calcium, so that it cannot activate the coagulation process and thereby prevent blood clotting in blood banks. So, the correct answer is 'Ca${}^{2+}$.