QUESTIONS AND ANSWERS WITH
SOLUTIONS 2024
Platelets are derived from? - ANSWER megakaryocytes
Reference Range for platelets is - ANSWER 150,000-400,000/mm3
Steps in platelet plug formation - ANSWER 1. platelet adhesion
2. platelet release reaction
3. platelet aggregation
Adhesion of Platelet Plug formation includes: - ANSWER Glycoprotein Ib binds to exposed collagen
Requires von Willebrands Factor
Results in release of ADP and other granule components (including Factor V and fibrinogen)
Aggregation of Platelet plug formation - ANSWER Other platelets stimulated by ADP to undergo shape
change exposing the glycoprotein IIb/IIIa complex which binds fibrinogen
Fibrinogen binding links the platelets with weak stimuli, the aggregates can disassociated.
Localization of the platelet plug - ANSWER Secreting platelets release arachidonic acid which converts to
prostaglandin, becomes thromboxane A2 in the platelet.
Arachidonic acid is processed by adjacent endothelial cells to form platelet-inhibiting prostacyclin
Assembly and localization of the fibrin clot. - ANSWER Platelet release fibrinogen, Factor V, and Factpr
VIII
Fibrinogen is bound on the surface at aggregation
Factor VIII is bound to the platelet surface with von Willebrand factors
, Shape change exposes platelet membrane phospholipid
Substrate of Factor I - ANSWER Fibrinogen
Cofactors - accelerate enzymatic reactions are: - ANSWER Factors III (3), V (5) and VIII (8)
Enzymes Serine proteases - ANSWER Cleave peptide bonds (Factors II (2), VII (7), IX (9), X (10), XI (11),
and XII (12))
Contact Proteins are - ANSWER Factors 12, 11, prekallikrein, and HMWK
Participate in initial phase of the intrinsic system
NOT consumed during clotting
NOT vitamin K dependent
Prothrombin Proteins - ANSWER Factors II, VII, IX, X
Vitamin K Dependent
NOT consumed during clotting (Except II)
Present in fresh and stored plasma and serum
Fibrinogen proteins - ANSWER Factors I, V, VIII, XIII
Consumed during clotting