Coagulation Pathways and Clotting Cascade

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Questions and Answers

What is the role of platelets in blood clotting?

Forming a plug at the site of vessel damage (correct)

Breaking down fibrin clots

Regulating the vitamin K cycle

Initiating vasoconstriction

How long does hemostasis typically take to occur after a small blood vessel (capillary) is damaged?

3-6 hours (correct)

1-2 minutes

10-15 minutes

7-9 minutes

What is the first major event that occurs when a blood vessel is damaged?

Fibrinolysis

Formation of a platelet plug

Vasoconstriction (correct)

Activation of the vitamin K cycle

Which factor plays a role in regulating hemostasis and thrombosis by the vessel wall?

Platelets Signup and view all the answers

What is the main function of the fibrinolytic system?

Breaking down fibrin clots Signup and view all the answers

Which vitamin is involved in blood coagulation and the factors that need its cycle?

Vitamin K Signup and view all the answers

What is the function of thromboplastin in the clotting cascade?

Activation of the extrinsic pathway Signup and view all the answers

What is a thrombus?

A blood clot that forms in an unbroken vessel Signup and view all the answers

What causes deep vein thrombosis (DVT)?

Poor blood circulation Signup and view all the answers

What are the symptoms of Hemophilia A?

Prolonged bleeding even from minor injuries and excessive bruising Signup and view all the answers

What is the role of Factor VIII in the blood coagulation cascade?

Co-factor for the proteolytic activation of factor X by factor IXa Signup and view all the answers

Which cells express thrombomodulin and heparin sulfate to prevent inappropriate thrombi formation?

Endothelial cells Signup and view all the answers

What is the main role of thromboxane A2 in platelet activation?

Amplification of platelet activation and recruitment of additional platelets Signup and view all the answers

9.5

This is 9.5 choice A Signup and view all the answers

What causes myocardial infarction (coronary thrombosis or heart attack)?

Atherosclerotic plaques rupture, causing platelet activation, adhesion, and aggregation with subsequent thrombus formation within the coronary circulation. Signup and view all the answers

What is the function of prostacyclin (PGI2) in platelet aggregation?

Inhibition of platelet aggregation by increasing cyclic AMP levels. Signup and view all the answers

What is the role of thrombomodulin in the circulation?

It acts as a cofactor of thrombin-catalyzed activation of protein C and inhibits the procoagulant functions of thrombin. Signup and view all the answers

Which condition is caused by abnormal blood clotting throughout the body's blood vessels?

Disseminated Intravascular Coagulation (DIC) Signup and view all the answers

What is the main function of Protein C in the circulation?

It inhibits the procoagulant functions of thrombin. Signup and view all the answers

Which test is used to detect lupus anticoagulants and factor VIII inhibitors?

Kaolin Clotting Time (KCT) Signup and view all the answers

What is the role of D-dimer in the circulation?

It indicates the presence of a blood clot being degraded by fibrinolysis. Signup and view all the answers

Which condition results from Vitamin K deficiency?

Prolonged bleeding and coagulation time Signup and view all the answers

What is the main role of Protein S in the circulation?

Regulation of anticoagulation, inflammation, and cell death Signup and view all the answers

Which test is used to monitor individuals being treated with warfarin (Coumadin®)?

(INR) International Normalized Ratio Signup and view all the answers

What causes elevated D-dimer levels in the circulation?

(DIC) Disseminated Intravascular Coagulation Signup and view all the answers

What is the purpose of EDTA (Ethylenediaminotetraacetic acid) in terms of coagulation?

Chelation of calcium/divalent cations Signup and view all the answers

What does a prolonged Bleeding Time indicate?

Low platelet count Signup and view all the answers

What is the initial event that kicks off the clotting cascade?

Tissue factor exposure Signup and view all the answers

What role does tissue factor pathway inhibitor 1 play in the clotting cascade?

Turns off the extrinsic pathway Signup and view all the answers

Which factor has a significantly longer half-life when carried by intact VWF?

Factor VIII - Antihemophilic Factor Signup and view all the answers

What is the function of thromboxane A2 in blood clotting?

Increases platelet activation and aggregation Signup and view all the answers

Which test measures the function of the intrinsic pathway and the common pathway?

aPTT (partial thromboplastin time) Signup and view all the answers

What is the role of plasminogen activators in clot dissolution?

Activates plasminogen to plasmin Signup and view all the answers

Which physiological inhibitor of coagulation is activated by heparin and heparan?

Antithrombin III Signup and view all the answers

Which vitamin-K dependent plasma glycoprotein is synthesized in the liver?

Protein S Signup and view all the answers

What does an elevated D-dimer level indicate?

(FDP) or a small protein fragment present in the blood after a blood clot is degraded by fibrinolysis Signup and view all the answers

In contrast to thromboplastin, what is partial thromboplastin composed of?

Phospholipids and tissue factor III Signup and view all the answers

What is the main function of von Willebrand factor (VWF) in blood coagulation?

Binding and releasing factor VIII as needed for coagulation cascade Signup and view all the answers

Which two distinct Plasminogen Activators (PAs) initiate the conversion of plasminogen to plasmin?

Tissue plasminogen activator (t-PA) and urokinase Signup and view all the answers

Study Notes

Blood Coagulation and Hemostasis

Platelets play a crucial role in blood clotting by aggregating at the site of injury and releasing chemicals that attract more platelets.
Hemostasis typically takes 10-15 minutes to occur after a small blood vessel (capillary) is damaged.
The first major event that occurs when a blood vessel is damaged is the exposure of collagen and tissue factor, which triggers the platelet activation and clotting cascade.

Regulation of Hemostasis and Thrombosis

The vessel wall plays a role in regulating hemostasis and thrombosis through the release of factors such as thrombomodulin and heparin sulfate.
Thrombomodulin is expressed on the surface of endothelial cells and prevents inappropriate thrombi formation.

Fibrinolytic System

The main function of the fibrinolytic system is to dissolve blood clots through the action of plasminogen activators.

Vitamin K and Blood Coagulation

Vitamin K is involved in blood coagulation and the factors that need its cycle, including factors II, VII, IX, and X.

Clotting Cascade

Thromboplastin is a protein that plays a crucial role in the clotting cascade by triggering the conversion of prothrombin to thrombin.
Thromboxane A2 is a powerful platelet aggregator that plays a key role in platelet activation.
A thrombus is a blood clot that forms in a blood vessel, which can cause blockages and lead to cardiovascular disease.

Deep Vein Thrombosis (DVT)

DVT is caused by the formation of a thrombus in a deep vein, which can lead to pulmonary embolism.

Hemophilia A

Hemophilia A is a genetic disorder caused by a deficiency of Factor VIII, leading to prolonged bleeding times and easy bruising.
Symptoms of Hemophilia A include easy bruising, joint pain, and prolonged bleeding times.

Factor VIII

Factor VIII plays a crucial role in the blood coagulation cascade by activating factor IX and triggering the formation of a blood clot.

Thrombomodulin and Heparin Sulfate

Endothelial cells express thrombomodulin and heparin sulfate to prevent inappropriate thrombi formation.

Thromboxane A2

Thromboxane A2 is a powerful platelet aggregator that plays a key role in platelet activation.

Myocardial Infarction

Myocardial infarction (coronary thrombosis or heart attack) is caused by the formation of a thrombus in the coronary arteries, leading to blockages and tissue damage.

Prostacyclin (PGI2)

Prostacyclin (PGI2) is a potent inhibitor of platelet aggregation that prevents platelet activation.

Thrombomodulin

Thrombomodulin plays a key role in the circulation by regulating the coagulation cascade and preventing inappropriate thrombi formation.

Disseminated Intravascular Coagulation (DIC)

DIC is a condition caused by abnormal blood clotting throughout the body's blood vessels, leading to organ failure and death.

Protein C

Protein C is a natural anticoagulant that plays a crucial role in the circulation by regulating the coagulation cascade.

Protein S

Protein S is a natural anticoagulant that plays a crucial role in the circulation by regulating the coagulation cascade.

Lupus Anticoagulants and Factor VIII Inhibitors

The dilute Russell viper venom time (dRVVT) test is used to detect lupus anticoagulants and factor VIII inhibitors.

D-Dimer

D-dimer is a protein fragment that is produced when a blood clot is broken down, and is used as a marker of blood clotting activity.
Elevated D-dimer levels in the circulation indicate the presence of a blood clot.

Vitamin K Deficiency

Vitamin K deficiency can lead to a condition known as bleeding diathesis, characterized by easy bruising and prolonged bleeding times.

Warfarin (Coumadin®)

The International Normalized Ratio (INR) test is used to monitor individuals being treated with warfarin (Coumadin®).

EDTA (Ethylenediaminotetraacetic acid)

EDTA is a chelating agent that is used to prevent blood clotting in vitro.

Bleeding Time

A prolonged bleeding time indicates a defect in platelet function or a deficiency of platelet factors.

Clotting Cascade Initiation

The initial event that kicks off the clotting cascade is the exposure of collagen and tissue factor, which triggers the platelet activation and clotting cascade.

Tissue Factor Pathway Inhibitor 1

Tissue factor pathway inhibitor 1 plays a crucial role in the clotting cascade by regulating the activity of tissue factor.

von Willebrand Factor (VWF)

von Willebrand factor (VWF) is a protein that plays a crucial role in blood coagulation by promoting platelet aggregation and adhesion.

Plasminogen Activators

Plasminogen activators, such as tissue-type plasminogen activator (t-PA) and urokinase-type plasminogen activator (u-PA), initiate the conversion of plasminogen to plasmin, which dissolves blood clots.

Partial Thromboplastin

Partial thromboplastin is composed of phospholipids and platelet factor 3, which triggers the clotting cascade.

Thrombosis

Thrombosis is the formation of a blood clot in a blood vessel, which can cause blockages and lead to cardiovascular disease.

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Description

Explore the intertwined nature of the intrinsic and extrinsic pathways in blood clot formation, as well as the role of tissue factor in initiating the clotting cascade. Understand the significance of each pathway's contribution to efficient clotting in the body.