Week 5 Flashcards
(28 cards)
What is haemostasis? And the 5 components?
The process that prevents blood loss following injury while maintaining blood circulation.
Blood vessels, platelets, coagulation factors, coagulation inhibitors, fibrinolysis.
Where are platelets formed? and types?
In the bone marrow from megakaryocytes.
Dense granules, α-granules, lysosomes.
What are the two main pathways in the coagulation cascade?
Extrinsic (Tissue Factor pathway) and Intrinsic (Contact Activation pathway).
What factor initiates the extrinsic pathway?
Tissue Factor (Factor III).
Name two natural anticoagulants in the body.
Antithrombin and Protein C.
What does Tissue Factor Pathway Inhibitor (TFPI) do?
It inhibits the initiation of the coagulation cascade.
What enzyme breaks down fibrin?
Plasmin.
What is the inactive precursor of plasmin?
Plasminogen.
What laboratory test detects fibrinolysis?
D-dimer test.
What does Prothrombin Time (PT) measure?
The extrinsic pathway of coagulation.
What does Thrombin Time (TT) measure?
The ability to convert fibrinogen to fibrin.
What are the three layers of blood vessels?
Tunica intima (inner), tunica media (middle), tunica externa (outer).
What happens to blood vessels immediately after an injury?
Vasoconstriction occurs to reduce blood flow and promote platelet activation
What molecule do endothelial cells release to promote vasoconstriction?
Endothelin (ET-1).
What is the primary function of platelets in haemostasis?
Forming the initial platelet plug during primary haemostasis
What is the role of fibrinogen in platelet aggregation?
It acts as a bridge between activated platelets by binding to GPIIb/IIIa receptors.
What is the function of Factor II (Prothrombin)?
It is converted into thrombin, which converts fibrinogen into fibrin.
Which factor stabilizes the fibrin clot?
Factor XIII (Fibrin-Stabilizing Factor).
What is the role of calcium (Factor IV) in coagulation?
It allows coagulation factors to bind to phospholipid surfaces.
What does Protein C do?
Inactivates Factors Va and VIIIa to slow coagulation.
What is the function of Heparin Cofactor II?
It enhances thrombin inhibition.
What is the International Normalized Ratio (INR) used for?
Standardizing Prothrombin Time (PT) results across laboratories.
What does a fibrinogen assay measure?
The level of fibrinogen in plasma, important for clot formation.
What is Haemophilia A caused by?
Deficiency of Factor VIII.
