Questions and Answers
Compare and contrast the intrinsic and extrinsic pathway.
The extrinsic pathway has fewer steps, occurs rapidly due to tissue trauma, and initiates prothrombinase through factors outside blood vessels. The intrinsic pathway is more complex, slower, occurs due to blood trauma, and has activators in contact with blood.
Describe the three major steps the body takes to reduce blood loss.
- Extrinsic or intrinsic pathway leading to prothrombinase formation, 2. Common pathway converting prothrombin to thrombin, 3. Formation of fibrin network with thrombin and fibrinogen.
Explain the role of thrombin and fibrinogen in making a blood clot.
Thrombin stimulates the conversion of fibrinogen to fibrin, activating platelets to form a clot and speeding up the clotting process.
Explain the role of platelets in blood clotting.
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Study Notes
Blood Clotting - Hemostasis
- The extrinsic pathway of blood clotting is triggered by tissue trauma and has a rapid response with fewer steps compared to the intrinsic pathway, which is complex and slower, responding to blood trauma.
- Tissue factor or thromboplastin released from damaged cells in the extrinsic pathway activates platelets and initiates prothrombinase formation.
- The intrinsic pathway's activators are either in direct contact with blood or contained within the blood itself, ultimately also aiming to form prothrombinase.
- Internal bleeding from the intrinsic pathway is more dangerous as it is harder to detect, making quick intervention crucial.
Major Steps to Reduce Blood Loss
- The first step in clotting is the activation of either the extrinsic or intrinsic pathway, aiming to form prothrombinase based on the location of the damage (outside or inside the vessels).
- In the common pathway, prothrombinase converts prothrombin into thrombin, facilitating the next steps in clotting.
- The final goal is to form a fibrin network: thrombin acts on fibrinogen (the soluble form of fibrin), together with activated enzymes, to create a stable fibrin network that reinforces the clot.
- Hemostasis involves three stages: vascular spasm, platelet plug formation, and coagulation.
Role of Thrombin and Fibrinogen
- Thrombin accelerates the conversion of prothrombin to thrombin, enhancing clot formation speed.
- It activates platelets to promote faster formation of a platelet plug.
- Thrombin, in the presence of calcium, catalyzes the conversion of fibrinogen into fibrin, facilitating the formation of a stable fibrin network through the action of enzyme factors.
Role of Platelets in Blood Clotting
- Platelets adhere to damaged blood vessels, forming a temporary plug to stop bleeding.
- This platelet aggregate serves as a short-term solution until a more stable clot can be established as the hemostatic process proceeds.
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Description
This flashcard set covers the key concepts of hemostasis and blood clotting. You'll compare and contrast the intrinsic and extrinsic pathways, understanding their processes and characteristics. Perfect for those studying human physiology or medical terminology.
