Platelets and Hemostasis
Which of the following megakaryocyte membrane markers disappears as differentiation proceeds? a. CD34 b. CD41 c. CD61 d. CD42
a. CD34
Identify the platelet receptor and plasma protein required for normal platelet aggregation. a. GP IIb/IIIa fibrinogen b. GP IV factor VIII c. GP IV factor VIII d. PF4 factor V
a. GP IIb/IIIa fibrinogen
On what does factor VIII depend for stability? a. VWF b. platelets c. thrombin d. protein S
a. VWF
What vitamin is essential for normal synthesis of prothrombin group proteins, thus enabling them to bind Ca2+? a. Vitamin K b. vitamin B12 c. vitamin C d. vitamin D
a. Vitamin K
What substance is known to inactivate cyclooxygenase, causing impairment of platelet function? a. aspirin b. calcium c. tylenol d. vitamin K
a. aspirin
What plasma protein is important for normal wound healing and stabilization of the fibrin clot? a. tissue factor b. prothrombin c. factor Xa d. factor XIIIa
d. factor XIIIa
Oral anticoagulation is based on a. increasing plasminogen. b. activating plasmin. c. combining with antithrombin. d. vitamin K antagonism.
d. vitamin K antagonism.
What substance digests the fibrin clot after healing? a. plasmin b. activated protein C c. TPA d. 2-Antiplasmin
a. plasmin
Which of the following substances is stored in dense granules? a. serotonin b. platelet factor 4 c. fibronectin d. protein C inhibitor
a. serotonin
Which of the following is the most important protease of the coagulation pathway because of its role in so many different catalytic functions? a. thrombin b. factor XIa c. plasmin d. factor VIIa
a. thrombin
All of the following are functions of thrombin except a. activates factors V and VIII b. activates plasminogen c. activates factor XIII d. initiates platelet aggregation
b. activates plasminogen
Which of the following is part of primary hemostasis? a. fibrinolysis b. blood vessels c. intrinsic system d. inhibitors
b. blood vessels
Phospholipids in the platelet membrane are important for all of the following functions except a. supply of arachidonic acid. b. receptor for plasma fibrinogen. c. receptor for plasma coagulation enzymes. d. forms part of the platelet glycocalyx.
b. receptor for plasma fibrinogen.
Which of the following is the liver-secreted plasma enzyme that digests unused VWF? a. ADP b. TXA2 c. ADAMTS-13 d. GPIb
c. ADAMTS-13
Which of the following is necessary for platelet adhesion to collagen? a. calcium b. fibrinogen c. VWF d. factor XIII
c. VWF
Which of the following are components of the contact group of factors? a. fibrinogen and thrombin b. VIII and VWF c. XII and prekallikrein d. calcium and IX
c. XII and prekallikrein
Platelet agonists are substances that a. bind to phospholipid in the platelet membrane b. promote apoptosis c. activate platelets d. enhance megakaryocyte proliferation
c. activate platelets
Which of the following accurately describes reticulated (stress) platelets? a. They appear in compensation for thrombocytopenia. b. They are smaller than mature circulating platelets. c. Their diameter exceeds 6 um. d. Both a and c are true.
d. Both a and c are true.
Identify the platelet receptor and plasma protein required for normal platelet adhesion a. glycoprotein (GP) IV factor VIII b. platelet factor 4 (PF4) factor V c. gp IIb/IIIa fibrinogen d. gp Ib/IX/V von Willebrand factor (VWF)
d. gp Ib/IX/V von Willebrand factor (VWF)
What happens to the fibrin monomers created when thrombin cleaves fibrinopeptides A and B from fibrinogen? a. immediately inactivated to prevent excess clotting b. converted to plasminogen c. digested quickly by tissue plasminogen activator (TPA) d. polymerized and are stabilized by factor XIIIa
d. polymerized and are stabilized by factor XIIIa
