clot science definition

A soft insoluble mass formed when blood or lymph gels. During blood clotting, white blood cells, red blood cells, platelets, and various clotting factors interact in a cascade of chemical reactions initiated by a wound. When a body tissue is injured, calcium ions and platelets act on prothrombin to produce the enzyme thrombin. Thrombin then catalyzes the conversion of the protein fibrinogen into fibrin, a fibrous protein that holds the clot together. An abnormal clot inside the blood vessels or the heart (a thrombus  or an embolus ) can obstruct blood flow.