Coagulation/Platelets Flashcards
At low shear conditions, which of the following substances is NOT important for platelet adhesion:
a. Collagen
b. Thrombin
c. Fibronectin
d. Laminin
b. Thrombin
c. Fibronectin
d. Laminin
The following inherited platelet disorder is NOT reported to have abnormal clot retraction times:
a. Cyclic hematopoiesis
b. Chediak-Higashi syndrome
c. CalDAG-GEFI syndromes
d. Glanzmann thrombasthenia
C. Normal clot retraction occurs in the CalDAG-GEFI platelet disorders (canine thrombopathias)
because these platelets can interact with thrombin and express fibrinogen receptors.
Endothelial cells express substances on the surface that degrade platelet agonists, and synthesize inhibitors of platelet activation. Which of the following substances inhibits platelet activation?
a. Prostacyclin
b. ADP
c. Thrombin
d. Fibrinogen
a. Prostacyclin
When stimulated by [ADP, thromboxane, thrombin and PAF (platelet activating factor)] endothelial cells produce prostacyclin
The following is most true regarding platelet hypofunction due to anti-platelet antibodies:
a. Antibodies are usually directed at platelet DNA.
b. Antibodies are usually directed at membranous proteins, including GPIIb-IIIa.
c. Antibodies are directed at RBC antigens (Ag’s) and cross react with platelet Ag’s.
d. Antibody mechanisms are not exploited with drugs such as Plavix.
b. Antibodies are usually directed at membranous proteins, including GPIIb-IIIa.
reduced function may be explained by the finding that GPIIb/IIIa (fibrinogen receptor) and GPIb-IX (part of vWF receptor complex) are the most frequently targeted antigens
Anti-inflammatory agents inhibit platelet function through:
a. Activation of the cyclooxygenase (COX) enzyme system.
b. Inactivation of the COX enzyme system.
c. Increasing the amount of thromboxane A2 (TXA2)
d. Ablation of the COX enzymes and their related proteins.
b. Inactivation of the COX enzyme system.
The most common inherited intrinsic platelet disorder in dogs, and possibly other species, is characterized by a decrease to absent response to most platelet-activating agents, including ADP and collagen. What is the molecular bases for these disorders?
a. Mutation in the platelet ADP receptor P2Y12.
b. Mutation in the gene encoding adaptor protein complex 3 (AP3) beta-subunit
c. Mutation within the gene sequence that encode highly conserved calcium-binding domains within the GPIIb.
d. Mutation in the gene encoding calcium diacylglycerol guanine nucleotide exchange factor I (CalDAG-GEFI)
a. Mutation in the platelet ADP receptor P2Y12.
Which one of the following factors is involved in preventing platelet adherence to normal endothelial cells?
a. ADPases
b. Heparan sulfate
c. Prostacyclin
d. Thrombomodulin
a. ADPases
can degrade ADP released from activated platelets
Which one of the following factors mediates platelet aggregation only in low shear conditions?
a. Adenosine diphosphate (ADP)
b. Fibrinogen
c. Thrombin
d. Von Willebrand Factor (vWF)
a. Adenosine diphosphate (ADP)
b. Fibrinogen
c. Thrombin
????
High shear forces
Von Willebrand Factor (vWF)
Which of the following intrinsic platelet disorders also affect melanocytes? I. Glanzmann Thrombasthenia II. Chediak-Higashi Syndrome III. Cyclic Hematopoiesis IV. Scott Syndrome
A. I and II B. I and III C. II and III D. I, III, and IV E. I, II, III, and IV
C.
II. Chediak-Higashi Syndrome
III. Cyclic Hematopoiesis
All of the following contribute to platelet antagonism EXCEPT:
a. Erythropoietin
b. Heparan Sulfate
c. Thrombomodulin
d. Liver Insufficiency
a. Erythropoietin
All of the following contribute to the anti-thrombotic activity of the endothelium EXCEPT:
a. Nitric Oxide
b. Prostacyclin
c. Thrombomodulin
d. von Willebrand Factor
d. von Willebrand Factor
Type 1 Von Willebrand Disease is characterized by which of the following:
a. An equal decrease in all sizes of multimers of VWF
b. A decrease in only the large multimers of VWF
c. A decrease in only the small multimers of VWF
d. An absence of all multimers of VWF
a. An equal decrease in all sizes of multimers of VWF
A decrease in only the large multimers of VWF - TYPE II
An absence of all multimers of VWF = TYPE III
Which of the following platelet agonists are not synthesized de novo within platelets upon activation?
a. TXA2
b. 12-HETE
c. PAF
d. ADP
a. TXA2
Cyclic Hematopoesis is an inherited thrombocytopathia which results from which of the following platelet defects?
a. ADP receptor malformation
b. Failure of activation of β integrins
c. Lack of dense granules
d. β-tubulin defect/malformation
c. Lack of dense granules
ADP receptor malformation - P2Y12 gene
Failure of activation of β integrins - Kindlin-3 Disorder
β-tubulin defect/malformation - hereditary macrothrombocytopenia
Under low shear conditions, platelet adhesion to the subendothelium occurs via which of the following:
a. collagen , VWF, and fibronectin
b. collagen, laminin
c. collagen, VWF
d. collagen, fibronectin and laminin
a. collagen , VWF, and fibronectin
The gene defect responsible for several signal transduction disorders, including Basset hound, Landseer-ECT, and bovine thrombopathias, is:
a. CalDAG-GEFI
b. P2Y12
c. beta 1 tubulin
d. Kindlin 3
a. CalDAG-GEFI
Fibrin degradation products are removed from the body via:
a. splenic macrophages
b. filtration at the glomerulus
c. hepatic macrophages (Kupffer cells)
d. biliary excretion
c. hepatic macrophages (Kupffer cells)
Thrombopoeitin is responsible for stimulating platelet synthesis in the bone marrow. Which of the following is true regarding thrombopoeitin?
a. Thrombopoeitin is made only in the bone marrow and smooth muscle cells.
b. Thrombopoeitin production is upregulated in response to low platelet numbers.
c. Thrombopoeitin is regulated through a positive feedback mechanism.
d. Thrombopoeitin is cleared from circulation by adsorption onto platelets.
d. Thrombopoeitin is cleared from circulation by adsorption onto platelets.
During high shear conditions, which factors mediate platelet adhesion to subendothelial connective tissue?
a. Fibrinogen and GPIIb-IIIa
b. VWF, GPIb-IX-V complex, and collagen
c. Collagen, fibronectin, and laminin
d. VWF and GPIb-IX-V complex
d. VWF and GPIb-IX-V complex
Chediak Higashi syndrome is characterized by:
a. Absent or reduced expression of GPIIb-IIIa
b. A mutation in the gene encoding CalDAG-GEFI
c. Absence of dense granules in platelets
d. Failure of activation of β1, β2, and β3 type integrins
c. Absence of dense granules in platelets
All of the following substances are found in dense granules except.
a. ATP
b. ADP
c. Fibrinogen
d. Calcium ions
c. Fibrinogen
The mutation of what gene is associated with signal transduction disorders?
a. KINDLIN3
b. CalDAG-GEFI
c. P2Y12
d. P2Y
b. CalDAG-GEFI
In what disease will you see normal platelet function, but secondary hemostasis is affected because of an inability of express phosphatodylserine (PF3, PCA) or prothrombase on the surface of the platelet?
a. Beta tubulin deficiency
b. Dense Granule Defect
c. Scott’s Syndrome
d. Chediak- Higahi Syndrome
c. Scott’s Syndrome
What is the next step in hemostasis after platelets attach to the endothelium via vWF and collagen?
a. Prostacyclin is released from the platelet
b. The platelet undergoes a conformational change, exposing Integrin αIIbβ3
c. Dense granules release ADP, ATP, and histamine
d. Plasminogen is activated to plasmin
b. The platelet undergoes a conformational change, exposing Integrin αIIbβ3