Hemodynamic Disorders Quiz

Questions and Answers

What mediates platelet adhesion to the extracellular matrix?

Thrombin

Plasminogen

von Willebrand factor (vWF) (correct)

Fibrinogen

Which substance is released from dense body granules during platelet secretion?

Fibrinogen

Prothrombin

Histamine (correct)

Thromboxane A2

What is the primary stimulus for platelet aggregation?

Adenosine monophosphate (AMP)

Vascular endothelial growth factor (VEGF)

Thromboxane A2 (TXA2) (correct)

Platelet-activating factor (PAF)

What process leads to the formation of an irreversible hemostatic plug?

Coagulation cascade activation Signup and view all the answers

Which of the following triggers the secretion of tissue factor in endothelial cells?

Cytokines like tumor necrosis factor (TNF) Signup and view all the answers

What role does plasminogen activator inhibitor (PAI) have in the context of hemostasis?

Inhibits plasminogen activation Signup and view all the answers

What is the significance of the interaction between thrombin and the platelet surface receptor PAR?

It induces further platelet aggregation Signup and view all the answers

What is the main component of the definitive secondary hemostatic plug?

Fibrin mesh Signup and view all the answers

What role does thrombin play in the coagulation process?

It converts fibrinogen to fibrin. Signup and view all the answers

What is the result of fibrin polymerization in the hemostatic process?

Encapsulation of platelets and circulating cells. Signup and view all the answers

Which natural anticoagulants help control clotting in the body?

Antithrombins, proteins C and S, and TFPI. Signup and view all the answers

What initiates the fibrinolytic cascade after clot formation?

Activation of plasminogen. Signup and view all the answers

What is the primary function of plasmin in the coagulation process?

To break down fibrin and prevent polymerization. Signup and view all the answers

How is plasminogen activated in the body?

Through enzymatic degradation by activators. Signup and view all the answers

Which of the following tests assess the coagulation assay?

PT, PTT, and INR. Signup and view all the answers

What happens to free plasmin in the circulatory system?

It is inactivated by α2-antiplasmin. Signup and view all the answers

What direction do arterial thrombi typically grow from their point of attachment?

Retrograde direction Signup and view all the answers

What is a characteristic of venous thrombi in comparison to arterial thrombi?

They can create a long cast of the lumen. Signup and view all the answers

What term describes thrombi occurring in heart chambers or the aortic lumen?

Mural thrombi Signup and view all the answers

What is the primary compositional difference between arterial and venous thrombi?

Arterial thrombi are typically a meshwork of platelets and coagulation factors. Signup and view all the answers

Which of the following is a potential clinical risk associated with venous thrombi?

Embolization to the lungs Signup and view all the answers

What is the role of platelets in venous thrombosis compared to arterial thrombosis?

Platelets play a secondary role in venous thrombosis. Signup and view all the answers

What happens to a thrombus over time?

It can undergo organization and recanalization. Signup and view all the answers

Which of these components are mostly found in venous thrombi due to sluggish blood flow?

More enmeshed erythrocytes Signup and view all the answers

What is the primary function of the endothelium in maintaining hemostasis?

Preventing platelet adhesion and aggregation Signup and view all the answers

Which components are involved in both hemostasis and thrombosis?

Vascular wall, platelets, and the coagulation cascade Signup and view all the answers

Which molecule is NOT associated with anti-platelet effects of endothelial cells?

Thrombomodulin Signup and view all the answers

What happens when endothelial cells are injured or activated?

They can exhibit procoagulant activities Signup and view all the answers

What do heparin-like molecules and thrombomodulin have in common?

Both contribute to anticoagulant effects Signup and view all the answers

Which of the following describes the primary consequence of normal hemostasis?

Maintaining blood in a fluid, clot-free state Signup and view all the answers

What is the main role of the coagulation cascade in hemostasis?

To promote the rapid formation of a hemostatic plug Signup and view all the answers

What effect does the intact endothelium have on blood flow?

It facilitates unrestricted liquid blood flow Signup and view all the answers

Where do most venous thrombi typically occur?

In the superficial or deep veins of the leg Signup and view all the answers

Which type of venous thrombosis is less likely to embolize?

Superficial venous thrombi Signup and view all the answers

What can cause deep venous thrombosis besides stasis?

Hypercoagulable states Signup and view all the answers

What is a major initiator of thrombosis?

Atherosclerosis Signup and view all the answers

What percentage of emboli is represented by dislodged thrombus?

99% Signup and view all the answers

What complication can arise from thromboembolism?

Ischemic necrosis Signup and view all the answers

What is the annual death toll caused by pulmonary embolism in the United States?

200,000 Signup and view all the answers

Which condition can lead to the formation of atrial mural thrombi?

Mitral valve stenosis Signup and view all the answers

Study Notes

Hemodynamic Disorders, Thrombosis, and Shock

Cell and tissue health relies on intact circulation for oxygen delivery and waste removal.
Normal fluid homeostasis keeps blood in a liquid state until clotting is necessary.

Hemostasis and Thrombosis

Normal hemostasis involves processes that maintain clog-free blood flow while enabling localized clot formation at injury sites.
Three components of hemostasis and thrombosis: vascular wall, platelets, coagulation cascade.

Endothelium

Endothelial cells regulate both pro- and anti-thrombotic activities.
Balance between these activities influences thrombus formation, propagation, or dissolution.
Antithrombotic properties include:
- Antiplatelet effects: Prevent platelets from adhering and aggregating.
- Anticoagulant effects: Inhibition of the coagulation cascade via heparin-like molecules and thrombomodulin.
- Fibrinolytic effects: Enable clot dissolution using plasminogen activator (t-PA).

Prothrombotic Properties

Injury to endothelium promotes platelet adhesion through von Willebrand factor (vWF).
Endothelial cells can produce tissue factor, initiating the extrinsic clotting cascade, especially in response to cytokines.
Antifibrinolytic effects include secretion of plasminogen activator inhibitors (PAIs).

Platelets

Central to normal hemostasis, platelets adhere to the extracellular matrix mediated by vWF.
Platelet activation leads to granule secretion, releasing ADP, calcium, histamine, and other substances.
Aggregation occurs through ADP and thromboxane A2 (TXA2), forming a reversible primary hemostatic plug.
Thrombin enhances irreversible aggregation and converts fibrinogen to fibrin, solidifying the secondary hemostatic plug.

Coagulation Cascade

Consists of a series of enzymatic conversions leading to thrombin production, which converts fibrinogen into fibrin.
Restriction of coagulation to the injury site is critical to prevent excessive clotting.
Natural anticoagulants like antithrombin III, proteins C and S, and tissue factor pathway inhibitor (TFPI) regulate this process.
Fibrinolysis, primarily through plasmin, counteracts clot formation, ensuring balance.

Thrombus Characteristics

Thrombus size and shape depend on origin and cause; arterial thrombi grow retrograde while venous thrombi follow blood flow.
Thrombi show lines of Zahn, indicative of layered structure.
Mural thrombi can occur in heart chambers and the aorta, often occlusive and composed of platelets and fibrin.

Clinical Correlations

Venous thrombi lead to tissue congestion distal to blockages and can embolize to the lungs, posing a significant risk of death.
Arterial thrombi are critical due to their potential to cause significant vascular obstruction, especially in coronary and cerebral vessels.
Most venous thrombi occur in the legs, especially within deep veins, with superficial thrombi being less likely to embolize.

Embolism

An embolus is a detached mass that travels through the bloodstream, often resulting from dislodged thrombi (thromboembolism).
Other embolus types include fat droplets, air bubbles, cholesterol debris, and tumor fragments.
Consequences of thromboembolism include tissue ischemia and necrosis (infarction).

Pulmonary Thromboembolism

Incidence is 20 to 25 per 100,000 hospitalized patients, contributing to around 200,000 deaths annually in the U.S.
Improvement noted in fatality rates from 6% to 2% over the past quarter century.

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Description

This quiz explores the concepts of hemodynamic disorders, thrombosis, and shock, focusing on the importance of circulation and fluid homeostasis. Test your understanding of how the body maintains blood in a liquid state and the mechanisms involved in clot formation. Delve into the intricacies of normal hemostasis and its implications in health.