Questions and Answers
Describe the process of hemostasis.
- Primary hemostasis: coagulation cascade activates clotting factors leading to blood clot formation. 2. Secondary hemostasis: formation of a fibrin clot through intrinsic and extrinsic pathways. 3. Final stage: clot retraction or fibrinolysis, where plasmin removes the blood clot.
What is the function of an anticoagulant?
Slows down the cascade (blood thinner) or speeds up fibrinolysis.
Describe how fibrinolysis works.
Factor XII activates thrombin release which turns plasminogen to plasmin, digesting fibrinogen and fibrin, and inactivates factors V and VIII.
What is hemostasis?
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What are the consequences of inadequate hemostasis and excessive hemostasis?
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Why are calcium and vitamin K important in hemostasis?
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What does a D-dimer test for?
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What is the pathogenesis and treatment for hemophilia? What is the difference between types A and B?
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What is the pathogenesis and treatment for von Willebrand disease?
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What is the pathogenesis and treatment for DIC?
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What is the pathogenesis and treatment for hepatic disease?
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What is the difference between blood thinners and blood busters?
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Study Notes
Hemostasis Process
- Primary hemostasis involves the formation of a platelet plug and triggers the coagulation cascade within seconds after a vascular injury.
- Secondary hemostasis leads to fibrin clot formation through intrinsic and extrinsic pathways, completed within minutes.
- Final stage, clot retraction or fibrinolysis, dissolves the blood clot over two weeks, facilitated by plasmin.
Anticoagulant Function
- Anticoagulants act as blood thinners, slowing down the coagulation cascade.
- They can also speed up fibrinolysis, aiding in the dissolution of existing clots.
Fibrinolysis Mechanism
- Factor XII and thrombin release plasminogen activators, converting plasminogen to plasmin.
- Plasmin digests fibrinogen and fibrin, and inactivates factors V and VIII.
- This process prevents the formation of new clots by removing existing ones.
Definition of Hemostasis
- Hemostasis is the process of arresting bleeding and preventing blood loss following blood vessel injury.
- It requires the cooperation of vessel walls, circulating platelets, plasma coagulation proteins, calcium, and vitamin K.
Consequences of Hemostasis Imbalance
- Inadequate hemostasis leads to excessive bleeding.
- Excessive hemostasis results in clotting and thrombosis.
Importance of Calcium and Vitamin K
- Calcium is crucial for various steps in the coagulation cascade.
- Vitamin K is essential for synthesizing certain coagulation factors.
D-dimer Test
- The D-dimer test detects fibrin degradation products, indicating ongoing fibrinolysis.
Hemophilia Overview
- Hemophilia is an X-linked recessive disorder mainly affecting males, causing excessive bleeding.
- Hemophilia A involves factor VIII deficiency, while Hemophilia B (Christmas disease) features factor IX deficiency.
- Key symptom is hemarthrosis (bleeding into the joints).
- Treatment options: Factor VIII concentrates for Hemophilia A, fresh frozen plasma or cryoprecipitate for Hemophilia B.
Von Willebrand Disease
- An autosomal dominant disorder causing excessive bleeding with equal prevalence in males and females.
- Disrupts the coagulation cascade due to a deficiency of von Willebrand factor.
- Treatment includes desmopressin, cryoprecipitate, and avoidance of aspirin.
Disseminated Intravascular Coagulation (DIC)
- DIC starts with abnormal blood clot formation leading to bleeding; has a high fatality rate (~50%).
- Characterized by decreased fibrinogen and platelet counts, increased bleeding time, and elevated PT/INR/aPTT levels.
- Elevated D-dimer indicates ongoing fibrinolysis.
- Treatment includes frozen plasma, packed RBCs, platelets, cryoprecipitate, and heparin.
Hepatic Disease and Coagulation
- Hepatic disease affects the absorption of vitamin K, leading to decreased synthesis of coagulation factors.
- Results in the inability to remove activated clotting factors.
- Treatment involves administering vitamin K.
Blood Thinners vs. Thrombolytics
- Blood thinners are designed to prevent blood clot formation.
- Blood busters (thrombolytics) break down existing blood clots and are typically used for larger clots.
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Description
Dive into Chapter 14 of Pathophysiology as we explore the intricate processes involved in hemostasis and blood coagulation. Understand primary and secondary hemostasis, and how the body effectively responds to vascular injury through clot formation. Test your knowledge with helpful flashcards!