Final answer:
Sodium citrate acts as an anticoagulant by chelating calcium ions in the blood, which prevents the conversion of prothrombin to thrombin and ultimately inhibits blood clot formation. Its mode of action is similar to other calcium-binding anticoagulants, and it's used in both clinical and laboratory settings to preserve blood samples by preventing coagulation. Correct option is a. Anticoagulant.
Step-by-step explanation:
The mode of action of sodium citrate is as an anticoagulant. It achieves this by chelating calcium ions in the blood, which are critical for the blood coagulation process. Calcium ions are necessary for the enzymic conversion of prothrombin into thrombin and the subsequent production of thromboplastin. By binding calcium, sodium citrate prevents clot formation, making it an effective anticoagulant. This mechanism is similar to other anticoagulants like EDTA and oxalates, which also precipitate calcium into their respective insoluble salts to inhibit coagulation.
Other circulating plasma anticoagulants, such as the protein C system, TFPI (tissue factor pathway inhibitor), and antithrombin, also play important roles in controlling coagulation by inactivating clotting factors and inhibiting conversion of certain coagulation factors in various pathways. Pharmaceutical anticoagulants, like heparin, have similar purposes and can be administered to prevent clot formation in at-risk patients, such as those undergoing surgery. The Correct option is a. Anticoagulant.