fi'brin

A protein obtained from the blood, lymph, and some of the exudates. It is an insoluble protein, formed from the soluble fibrinogen by the action of thrombin. It is deposited in fine threads which form a jelly or coagulum. It may be obtained from the blood by whipping it with a bundle of twigs, f. factor. A term for substances in the blood, supposed to participate in the formation of f. f. ferment. The name given to a substance formed in shed blood, which converts the fibrinogen to fibrin. It is usually a umed to be a ferment, otherwise known as thrombin. It is formed, or activated, from a substance, prothrombin, existing in the circulating blood, vegetable f. See gluten. [Lat., fibrinum.]