Coagulation Factors and Cascade

Which coagulation factor is primarily produced in the liver?

What triggers the intrinsic pathway of the coagulation cascade?

Which of the following statements about Factor III is accurate?

Which test reflects the intrinsic pathway of coagulation?

What condition commonly causes prolongation of prothrombin time (PT)?

Which of the following statements about anticoagulant drugs is true?

What is the role of thrombin in the coagulation cascade?

What does APTT reflect in terms of coagulation?

Which of the following best describes the term 'embolus'?

Which coagulation factor is essential for the conversion of prothrombin to thrombin?

Coagulation Factors

Most coagulation factors are produced in the liver
Factor III (tissue factor) and factor IV (calcium ions) are produced by other cells, including endothelial cells and platelets

Coagulation Cascade

Occurs at site of injury
Intrinsic pathway: activated by blood vessel damage and collagen exposure
Extrinsic pathway: triggered by tissue factor (factor III) release from damaged tissues
Common pathway: both pathways converge to produce factor Xa, which converts prothrombin (factor II) into thrombin (factor IIa), leading to fibrinogen (factor I) conversion into fibrin
Factor Xa is responsible for clot formation

Coagulation Tests

Activated partial thromboplastin time (APTT) reflects the intrinsic pathway and can indicate deficiencies in factors VIII, IX, XI, or XII
Prothrombin time (PT) reflects the extrinsic pathway and can indicate factor VII deficiency
Common pathway deficiencies in factors V, X, thrombin, and fibrinogen prolong both APTT and PT
Thrombin clotting time (TCT) measures the final step of coagulation, converting fibrinogen to fibrin via thrombin action
Prolonged TCT can be due to deficiencies in fibrinogen and direct or indirect thrombin inhibitors

Classes and Drug Use

Factor Xa and direct thrombin inhibitors can be taken at home, in contrast to heparin and vitamin K antagonists
Drugs do not dissolve existing clots, but prevent new clots from forming and stop existing clots from worsening
Thrombus: a blood clot formed abnormally within blood vessels
Embolus: a blood clot dislodged from a vessel wall and travels through the bloodstream

This quiz covers the essential aspects of coagulation factors, their production, and the mechanisms involved in the coagulation cascade. Learn how intrinsic and extrinsic pathways operate, and understand the significance of various coagulation tests in diagnosing deficiencies. Perfect for students and professionals seeking to enhance their knowledge of hemostasis.