Hagemann factor is involved in: March 2009
**Core Concept**
The Hageman factor, also known as factor XII, plays a crucial role in the initiation of the intrinsic coagulation pathway. This pathway is a complex series of biochemical reactions that ultimately lead to the formation of a blood clot.
**Why the Correct Answer is Right**
The intrinsic coagulation pathway is activated when blood comes into contact with a foreign surface, such as glass or a damaged blood vessel wall. Hageman factor, or factor XII, is the first enzyme in this pathway, which is activated by contact with negatively charged surfaces. This activation leads to a cascade of enzyme-substrate reactions, ultimately resulting in the conversion of prothrombin to thrombin and the formation of a blood clot. Hageman factor's role is to initiate this cascade, making it a critical component of the intrinsic coagulation pathway.
**Why Each Wrong Option is Incorrect**
**Option A:** The extrinsic coagulation pathway is initiated by the release of tissue factor from damaged tissues, not by Hageman factor. While both pathways ultimately lead to the formation of a blood clot, they are distinct and Hageman factor is not involved in the extrinsic pathway.
**Option C:** Fibrinolysis is the process by which blood clots are broken down, and it is not directly related to Hageman factor. Hageman factor is involved in clot formation, not clot degradation.
**Option D:** This option is incorrect because Hageman factor is indeed involved in the coagulation process, specifically in the intrinsic coagulation pathway.
**Clinical Pearl / High-Yield Fact**
Hageman factor deficiency is a rare genetic disorder that increases the risk of bleeding. Patients with this disorder may experience prolonged bleeding after injury or surgery, highlighting the importance of Hageman factor in the intrinsic coagulation pathway.
**β Correct Answer: B. Intrinsic pathway**