Final answer:
The common pathway in blood coagulation is demonstrated by the activation of factor X, which leads to the conversion of prothrombin to thrombin, and finally the conversion of fibrinogen to fibrin to form a stable blood clot. Clotting factors, which include calcium ions and vitamin K, play a vital role in this process.
Step-by-step explanation:
The lower common pathway is demonstrated in the coagulation process, which is the final coagulation pathway activated either by the intrinsic or the extrinsic pathway. This process results in the formation of a blood clot. Both the intrinsic and extrinsic pathways merge into the common pathway, which involves several clotting factors secreted primarily by the liver and the platelets. The activation of factor X leads to the conversion of prothrombin into thrombin by the enzyme prothrombinase. Thrombin then catalyzes the conversion of fibrinogen into the insoluble protein fibrin, which is stabilized by factor XIII to form a blood clot.
Clotting factors, including calcium ions and vitamin K, are essential for coagulation. Vitamin K is necessary for the production of many clotting factors by the liver, and it is obtained from the diet as well as synthesized by bacteria in the large intestine. The calcium ion is crucial as factor IV, derived from dietary sources and the breakdown of bone.