Success! Hemostasis UPDATED Exam
Questions and CORRECT Answers
The hemorrhagic problems associated with scurvy are due to a deficiency of_____ , which is
a cofactor required for collagen synthesis.
A. Vitamin C
B. Prothrombin
C. Vitamin K
D. Protein C - CORRECT ANSWER- A.
Vascular integrity is influenced by vitamin C intake. In a deficiency or absence of vitamin C,
collagen production is insufficient or abnormal. Vitamin C deficiency is associated with
capillary fragility and the primary hemostasis bleeding symptoms of petechiae and mucosal
bleeding
The number of platelets an average megakaryocyte generates is approximately
A. 25-50
B. 50-200
C. 200-500
D. 2000-4000 - CORRECT ANSWER- D.
Each megakaryocyte produces approximately 2000- 4000 platelets. A single megakaryocyte
can generate this large number of cells because platelets are nonnucleated fragments of their
cytoplasm. The number of platelets generated by a megakaryocyte depends on its cell size,
which is directly related to the number of endomitotic divisions before cytoplasmic
fragmentation.
Which of the following is not a cause of thrombocytopenia?
A. Splenomegaly
B. Chemotherapy
C. Increased thrombopoietin
D. Aplastic anemia - CORRECT ANSWER- C.
Thrombopoietin is the major humoral factor involved in platelet production. Increased
thrombopoietin results in thrombocytosis; decreased thrombopoietin results in
thrombocytopenia. Two-thirds of platelets, once released from the bone marrow, are in
,circulation. The other onethird of platelets is sequestered in the spleen. Splenomegaly is a
cause of thrombocytopenia due to increased sequestration. Chemotherapeutic agents destroy
both normal and malignant cells, causing thrombocytopenia, anemia, and leukopenia.
Aplastic anemia occurs when the bone marrow fails to produce any of the three cell lines
Platelets interacting with and binding to other platelets is referred to as
A. Adhesion
B. Aggregation
C. Release
D. Retraction - CORRECT ANSWER- B.
"Adhesion" refers to platelets interacting with something other than platelets. In vivo platelets
adhere to collagen that is exposed when vessel damage occurs. "Aggregation" refers to
attachment of platelets to other platelets. Release is the process by which platelet granule
contents are secreted. Retraction describes one of the final steps in coagulation in which the
fibrin-platelet plug contracts, restoring normal blood flow to the vessel.
In platelet aggregation studies, certain aggregating agents induce a biphasic aggregation
curve. This second phase of aggregation is directly related to A. Formation of fibrin
B. Changes in platelet shape
C. Release of endogenous ADP
D. Release of platelet factor 3 - CORRECT ANSWER- C.
In platelet aggregation studies, the addition of the aggregating agent may induce an initial
aggregation phase followed by a secondary wave. The initial phase is due to the interaction of
the aggregating agent with the platelet. The second phase is due to release of nonmetabolic
ADP from platelet granules, which promotes the additional wave of aggregation.
A platelet aggregation agent that characteristically yields a biphasic curve when used in
optimal concentration is
A. Arachidonic acid
B. Collagen
C. Epinephrine
D. Ristocetin - CORRECT ANSWER- C.
Epinephrine is the only aggregating agent listed that typically gives a biphasic pattern. ADP
and thrombin also give biphasic patterns when used in optimal concentrations. Arachidonic
acid causes a rapid monophasic platelet aggregation. Collagen and ristocetin also induce
monophasic aggregatory responses
, The platelet aggregation pattern drawn below is characteristic of the aggregating agent
A. ADP
B. Collagen
C. Ristocetin
D. Thrombin - CORRECT ANSWER- B.
Collagen is the only aggregating agent that includes a single wave response preceded by a lag
phase. During the lag phase collagen stimulates platelets to release their granule contents.
Endogenous ADP released from the platelets then initiates irreversible platelet aggregation.
The operating principle of a platelet aggregometer is best described as
A. Aggregation on a foreign surface: Platelet aggregation is directly proportional to the
difference in platelet counts performed before and after platelet-rich plasma is passed through
a column of glass beads. B. Change in optical density: As platelets aggregate, the optical
density of the platelet-rich plasma decreases.
C. Electrical impedance: Platelet aggregates are counted as they pass through an aperture,
temporarily interrupting the flow of current between two electrodes.
D. Pulse editing: Editing electronically generated pulses can differentiate the number of free
platelets versus platelet aggregates. - CORRECT ANSWER- B.
When an aggregating agent is added to an optically dense suspension of platelet-rich plasma
(PRP), the platelets normally stick to each other, forming platelet aggregates. As additional
platelets aggregate, the cell suspension becomes clearer and has a few large clumps of cells.
At maximum aggregation the specimen is relatively clear, allowing light transmission that is
only partially obstructed by a few large platelet aggregates
Of the following therapeutic agents, those considered to be antiplatelet medications are
A. Aspirin and Plavix®
B. Coumadin® and heparin
C. Heparin and protamine sulfate D. Tissue plasminogen activator and streptokinase -
CORRECT ANSWER- A.
Aspirin inhibits the enzyme cyclooxygenase in the prostaglandin pathway, preventing platelet
aggregation. Plavix® (clopidogrel bisulfate) blocks the Ilb/IIIa fibrinogen-binding platelet
receptor, preventing platelet aggregation. Coumadin® and heparin inhibit clotting factors in
secondary hemostasis. Protamine sulfate can be used to neutralize heparin. Tissue
plasminogen activator and streptokinase are fibrinolytic system activators
Questions and CORRECT Answers
The hemorrhagic problems associated with scurvy are due to a deficiency of_____ , which is
a cofactor required for collagen synthesis.
A. Vitamin C
B. Prothrombin
C. Vitamin K
D. Protein C - CORRECT ANSWER- A.
Vascular integrity is influenced by vitamin C intake. In a deficiency or absence of vitamin C,
collagen production is insufficient or abnormal. Vitamin C deficiency is associated with
capillary fragility and the primary hemostasis bleeding symptoms of petechiae and mucosal
bleeding
The number of platelets an average megakaryocyte generates is approximately
A. 25-50
B. 50-200
C. 200-500
D. 2000-4000 - CORRECT ANSWER- D.
Each megakaryocyte produces approximately 2000- 4000 platelets. A single megakaryocyte
can generate this large number of cells because platelets are nonnucleated fragments of their
cytoplasm. The number of platelets generated by a megakaryocyte depends on its cell size,
which is directly related to the number of endomitotic divisions before cytoplasmic
fragmentation.
Which of the following is not a cause of thrombocytopenia?
A. Splenomegaly
B. Chemotherapy
C. Increased thrombopoietin
D. Aplastic anemia - CORRECT ANSWER- C.
Thrombopoietin is the major humoral factor involved in platelet production. Increased
thrombopoietin results in thrombocytosis; decreased thrombopoietin results in
thrombocytopenia. Two-thirds of platelets, once released from the bone marrow, are in
,circulation. The other onethird of platelets is sequestered in the spleen. Splenomegaly is a
cause of thrombocytopenia due to increased sequestration. Chemotherapeutic agents destroy
both normal and malignant cells, causing thrombocytopenia, anemia, and leukopenia.
Aplastic anemia occurs when the bone marrow fails to produce any of the three cell lines
Platelets interacting with and binding to other platelets is referred to as
A. Adhesion
B. Aggregation
C. Release
D. Retraction - CORRECT ANSWER- B.
"Adhesion" refers to platelets interacting with something other than platelets. In vivo platelets
adhere to collagen that is exposed when vessel damage occurs. "Aggregation" refers to
attachment of platelets to other platelets. Release is the process by which platelet granule
contents are secreted. Retraction describes one of the final steps in coagulation in which the
fibrin-platelet plug contracts, restoring normal blood flow to the vessel.
In platelet aggregation studies, certain aggregating agents induce a biphasic aggregation
curve. This second phase of aggregation is directly related to A. Formation of fibrin
B. Changes in platelet shape
C. Release of endogenous ADP
D. Release of platelet factor 3 - CORRECT ANSWER- C.
In platelet aggregation studies, the addition of the aggregating agent may induce an initial
aggregation phase followed by a secondary wave. The initial phase is due to the interaction of
the aggregating agent with the platelet. The second phase is due to release of nonmetabolic
ADP from platelet granules, which promotes the additional wave of aggregation.
A platelet aggregation agent that characteristically yields a biphasic curve when used in
optimal concentration is
A. Arachidonic acid
B. Collagen
C. Epinephrine
D. Ristocetin - CORRECT ANSWER- C.
Epinephrine is the only aggregating agent listed that typically gives a biphasic pattern. ADP
and thrombin also give biphasic patterns when used in optimal concentrations. Arachidonic
acid causes a rapid monophasic platelet aggregation. Collagen and ristocetin also induce
monophasic aggregatory responses
, The platelet aggregation pattern drawn below is characteristic of the aggregating agent
A. ADP
B. Collagen
C. Ristocetin
D. Thrombin - CORRECT ANSWER- B.
Collagen is the only aggregating agent that includes a single wave response preceded by a lag
phase. During the lag phase collagen stimulates platelets to release their granule contents.
Endogenous ADP released from the platelets then initiates irreversible platelet aggregation.
The operating principle of a platelet aggregometer is best described as
A. Aggregation on a foreign surface: Platelet aggregation is directly proportional to the
difference in platelet counts performed before and after platelet-rich plasma is passed through
a column of glass beads. B. Change in optical density: As platelets aggregate, the optical
density of the platelet-rich plasma decreases.
C. Electrical impedance: Platelet aggregates are counted as they pass through an aperture,
temporarily interrupting the flow of current between two electrodes.
D. Pulse editing: Editing electronically generated pulses can differentiate the number of free
platelets versus platelet aggregates. - CORRECT ANSWER- B.
When an aggregating agent is added to an optically dense suspension of platelet-rich plasma
(PRP), the platelets normally stick to each other, forming platelet aggregates. As additional
platelets aggregate, the cell suspension becomes clearer and has a few large clumps of cells.
At maximum aggregation the specimen is relatively clear, allowing light transmission that is
only partially obstructed by a few large platelet aggregates
Of the following therapeutic agents, those considered to be antiplatelet medications are
A. Aspirin and Plavix®
B. Coumadin® and heparin
C. Heparin and protamine sulfate D. Tissue plasminogen activator and streptokinase -
CORRECT ANSWER- A.
Aspirin inhibits the enzyme cyclooxygenase in the prostaglandin pathway, preventing platelet
aggregation. Plavix® (clopidogrel bisulfate) blocks the Ilb/IIIa fibrinogen-binding platelet
receptor, preventing platelet aggregation. Coumadin® and heparin inhibit clotting factors in
secondary hemostasis. Protamine sulfate can be used to neutralize heparin. Tissue
plasminogen activator and streptokinase are fibrinolytic system activators
