Integrated Clinical Science: Cardiology I – Thrombosis & Blood Clotting

These flashcards review key concepts from the lecture on blood clotting, platelet aggregation, the coagulation cascade, natural inhibitors, thrombosis pathophysiology, Virchow’s triad, thrombus classification, fate, and clinical consequences.

What are the two major components involved in forming a blood clot after vessel injury?

Platelet activation/aggregation and the coagulation cascade.

What physiological process stops bleeding by converting liquid blood to a gel-like clot and initiates vessel repair?

Hemostasis

In the clot structure analogy, platelets are the “bricks.” What acts as the “mortar”?

Fibrin

Which vasoconstrictive step immediately reduces blood flow at an injury site before platelets adhere?

Reflex vasoconstriction

Which two adhesive proteins anchor platelets to exposed sub-endothelium during the adhesion phase?

Collagen and von Willebrand factor (vWF)

Name the platelet surface receptor that binds collagen and the receptor complex that binds vWF.

GP VI binds collagen; GP Ib-IX-V binds vWF.

Which platelet receptor is up-regulated during activation to cross-link platelets via fibrinogen?

GP IIb/IIIa

List the three key agonists released from activated platelets that amplify aggregation.

ADP, serotonin, and thromboxane A₂ (TxA₂).

Which intracellular second messenger must fall and which ion must rise to drive platelet activation?

cAMP must decrease, and Ca²⁺ must increase.

Which enzyme degrades cAMP inside platelets and is a target of certain antiplatelet drugs?

Phosphodiesterase (PDE)

What are the two classic initiation pathways of the coagulation cascade?

Intrinsic pathway and extrinsic pathway.

Which pathway produces approximately 95 % of thrombin in physiologic clotting?

The intrinsic pathway.

Which coagulation factor provides the pivotal link between intrinsic/extrinsic pathways and the common pathway?

Factor X

What is the principal enzymatic product of the coagulation cascade that converts fibrinogen to fibrin?

Thrombin (Factor IIa)

Name the three natural anticoagulant systems that limit excessive coagulation.

Antithrombin III, Protein C, and TFPI.

Which vitamin-dependent factors are reduced by warfarin therapy?

Prothrombin (II) and Factors VII, IX, and X.

Provide the textbook definition of thrombosis.

Formation of a clotted mass within the cardiovascular system that obstructs blood flow.

What triad describes the three broad etiologic categories that predispose to thrombosis (endothelial injury, abnormal blood flow, and hypercoagulability)?

Virchow’s triad

Give three common causes of endothelial injury that promote thrombosis.

Atherosclerotic plaques, hypertension, and cigarette smoke.

How does slow blood flow (stasis) favor thrombosis formation in veins?

It allows platelets to migrate to the periphery, reduces washout of clotting factors, and decreases delivery of anticoagulants.

Name two genetic abnormalities that increase hypercoagulability.

Elevated prothrombin and decreased antithrombin III.

Which endothelial-derived molecules inhibit platelet adhesion and aggregation under normal conditions?

Nitric oxide (NO), prostacyclin (PGI₂), and adenosine diphosphatase.

Which endothelial cell surface molecule complexes with thrombin to activate Protein C?

Thrombomodulin

What fibrinolytic enzyme is released by endothelial cells to convert plasminogen to plasmin?

Tissue plasminogen activator (tPA)

Distinguish between a white (pale) thrombus and a red thrombus in composition and flow setting.

White thrombus: platelet-rich, forms in fast arterial flow. Red thrombus: fibrin and RBC-rich, forms in slow venous flow.

What are the four possible fates of a thrombus once formed?

Dissolution, propagation, embolization, and organization/recanalization.

What is meant by a “saddle” thrombus?

A thrombus lodged at a vessel bifurcation.

Define a “canalized” thrombus.

A thrombus that has formed new vascular channels, partially restoring blood flow.

Why are venous thrombi more likely to undergo organization while arterial thrombi more often recanalize?

Slower venous flow favors fibroblast infiltration and organization.

List the three classes of pharmacologic agents used to manage or prevent thrombosis.

Anticoagulants, antiplatelet drugs, and thrombolytics.

What life-threatening conditions can result from arterial or venous thrombosis, making it a leading global cause of death?

Myocardial infarction, ischemic stroke, and venous thromboembolism.

Which enzyme in the fibrinolytic system directly dissolves fibrin clots?

Plasmin

State two clinical or lifestyle factors that can cause acquired hypercoagulability.

Prolonged bed rest/immobilization and malignancy.

What is a mural thrombus?

A thrombus attached to the wall of the heart.

Explain how hepatic disease combined with bile deficiency can impair clotting.

It diminishes vitamin K absorption, prolonging bleeding.