Hemodynamic Disorders and Thrombosis

Questions and Answers

What is one of the primary roles of endothelial cells in maintaining hemostasis?

To promote platelet aggregation

To inhibit coagulation processes (correct)

To induce vascular injury

To enhance thrombus formation

What happens to the balance of endothelial cell activities after vascular injury?

They enhance only fibrinolytic effects

They solely exhibit antiplatelet properties

They can exhibit numerous procoagulant activities (correct)

They stop all coagulation processes

Which of the following substances exhibit antiplatelet effects on endothelial cells?

Vitamin K

Collagen

Thrombin

Prostacyclin (PGI2) (correct)

What is one main characteristic of a functional endothelium in relation to blood flow?

It prevents platelet adhesion and aggregation Signup and view all the answers

Which component is NOT involved in the process of hemostasis and thrombosis?

Bacterial enzymes Signup and view all the answers

What role does nitric oxide play in the context of endothelial cell function?

Inhibits platelet adhesion Signup and view all the answers

Which of the following processes is specifically prevented by an intact endothelium under normal circumstances?

Platelet adhesion Signup and view all the answers

What role does thrombin play in the coagulation process?

Thrombin converts fibrinogen to fibrin, stabilizing the clot. Signup and view all the answers

Which of the following properties is not typically exhibited by healthy endothelial cells?

Procoagulant effects Signup and view all the answers

Which proteins act as natural anticoagulants in the coagulation process?

Antithrombin, proteins C and S, and TFPI Signup and view all the answers

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

To degrade fibrin and moderate clot size Signup and view all the answers

How is plasminogen converted to plasmin?

By factor XII-dependent pathways or plasminogen activators Signup and view all the answers

What happens to free plasmin to prevent it from causing excessive clot breakdown?

It forms a complex with α2-antiplasmin. Signup and view all the answers

Why is it important to restrict activation of the coagulation cascade to local sites of vascular injury?

To prevent systemic clotting that can lead to thrombosis Signup and view all the answers

Which coagulation assay measures the effectiveness of the extrinsic pathway?

Prothrombin Time (PT) Signup and view all the answers

Which of the following factors does thrombin activate during the coagulation cascade?

Factor V and VIII Signup and view all the answers

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

In a retrograde direction Signup and view all the answers

Which of the following correctly describes venous thrombi?

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

What are the lines of Zahn associated with?

Microscopic examination of arterial thrombi Signup and view all the answers

What is a common consequence of deep venous thrombosis?

Embolization to distant sites Signup and view all the answers

Which type of thrombus is most likely to be occlusive?

Both arterial and venous thrombi Signup and view all the answers

Which condition is primarily associated with the formation of cardiac mural thrombi?

Myocardial infarction Signup and view all the answers

What is the primary cause of venous thrombosis?

Activation of the coagulation cascade Signup and view all the answers

What type of embolus is most commonly found in embolism cases?

Dislodged thrombus fragments Signup and view all the answers

Which of the following is a potential consequence of venous thrombosis?

Embolism to the lungs Signup and view all the answers

What is the primary initiator of thromboses related to arterial health?

Abnormal vascular flow Signup and view all the answers

Which risk factor is NOT commonly associated with deep venous thrombosis?

Increased physical activity Signup and view all the answers

What is the primary component of an arterial thrombus?

Platelets and fibrin meshwork Signup and view all the answers

Which type of thrombus is formed most significantly in slow circulation?

Red or stasis thrombus Signup and view all the answers

How has the rate of fatal pulmonary emboli changed over the last quarter century?

Decreased from 6% to 2% Signup and view all the answers

What condition can cause atrial mural thrombi related to mitral valve stenosis?

Rheumatic heart disease Signup and view all the answers

What term describes a detached mass carried by the blood to a distant site?

Embolus Signup and view all the answers

What is the primary source of venous emboli in more than 95% of cases?

Deep leg vein thrombi above the knee Signup and view all the answers

What percentage of pulmonary emboli are considered clinically silent?

60% to 80% Signup and view all the answers

What condition may occur when 60% or more of the pulmonary circulation is obstructed by emboli?

Cardiovascular collapse Signup and view all the answers

What percentage of systemic thromboembolism arises from intracardiac mural thrombi?

80% Signup and view all the answers

Which of the following is NOT a predisposing factor for deep vein thrombosis (DVT)?

Chronic hypertension Signup and view all the answers

What is the fatality rate associated with fat embolism syndrome?

10% Signup and view all the answers

What treatment is commonly administered for deep vein thrombosis?

Intravenous heparin Signup and view all the answers

Where do most systemic thromboemboli typically end up?

Lower extremities Signup and view all the answers

Study Notes

Hemodynamic Disorders and Circulation

Health of cells and tissues is reliant on intact circulation for oxygen delivery and waste removal.
Normal fluid homeostasis is essential to keep blood in liquid form until clot formation is necessary.

Hemostasis and Thrombosis

Hemostasis is a tightly regulated process that maintains blood in a fluid state and promotes localized clot formation at injury sites.
Key components involved are the vascular wall, platelets, and the coagulation cascade.

Endothelial Cells and Hemostasis

Endothelial cells balance antithrombotic and prothrombotic activities, impacting clot formation or dissolution.
They have antiplatelet, anticoagulant, and fibrinolytic properties under normal conditions.

Antithrombotic Properties

Antiplatelet effects include blocking platelet adhesion and aggregation.
Anticoagulant effects involve heparin-like molecules and thrombomodulin, preventing excessive clotting.
Fibrinolytic activity is conducted by endothelial cells to dissolve blood clots when necessary.

Coagulation Cascade

The cascade is a series of enzymatic activations that lead to thrombin formation, which converts fibrinogen to fibrin.
The process must be localized to prevent widespread clotting, moderated by natural anticoagulants: antithrombins, proteins C and S, and tissue factor pathway inhibitor (TFPI).
Fibrinolysis is managed by plasmin, generated from plasminogen, which dissolves the fibrin in clots.

Thrombus Characteristics

Thrombi are formed by the attachment of a clot to the vascular surface, with arterial thrombi growing retrograde and venous thrombi extending with blood flow.
Thrombi show lamination, known as lines of Zahn, and can occur as mural thrombi within heart chambers or aortic lumen.

Clinical Correlations: Venous vs. Arterial Thrombosis

Thrombi obstruct blood flow and can lead to emboli; venous thrombi risk embolization to the lungs, potentially causing death.
Arterial thrombi primarily obstruct critical vessels, leading to tissue infarction.

Venous Thrombosis (Phlebothrombosis)

Most commonly occurs in superficial or deep leg veins, particularly in the presence of varices.
Deep venous thrombosis (DVT) is more serious as it may embolize, occurring often due to stasis or hypercoagulable states.

Cardiac and Arterial Thrombosis

Atherosclerosis can initiate thrombosis through endothelial damage and abnormal flow.
Cardiac mural thrombi may arise post-myocardial infarction or due to rheumatic heart disease.

Embolism

An embolus can be any dislodged mass (thrombus, fat droplet, air bubble, etc.) that travels through the bloodstream.
The most common type is thromboembolism, where a portion of a thrombus detaches and causes ischemia in distant tissues.

Pulmonary Thromboembolism

Incidence estimated at 20 to 25 per 100,000 hospitalized patients, with approximately 200,000 annual deaths in the U.S.
Most cases originate from DVTs in deep leg veins; many pulmonary emboli are clinically silent but can lead to sudden death if significant obstruction occurs.

Systemic Thromboembolism

Refers to emboli within arterial circulation, largely arising from cardiac sources like mural thrombi.
Common sites for obstruction include lower extremities and the brain.

Deep Vein Thrombosis (DVT) Predisposing Factors

Risk factors include immobility, pregnancy, post-operative conditions, severe burns, heart failure, and cancer.
High-risk patients should receive preventive measures like heparin and leg compression during surgery.

Fat Embolism

Associated with fractures of long bones or soft tissue trauma, resulting in microscopic fat globules in circulation.
Symptoms include pulmonary insufficiency, neurological issues, anemia, and thrombocytopenia; fatality rate is about 10%.

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Description

This quiz covers essential concepts related to hemodynamic disorders, thrombosis, and shock. Explore the intricate processes that regulate blood circulation, hemostasis, and the significance of proper fluid homeostasis in maintaining health. Understand how these factors contribute to tissue oxygenation and waste removal.