Question 1

From where are additional platelets first derived when the circulating count decreases?

Accepted Answer

A) bone marrow 
B) stem cells 
C) cells marginated on vessel endothelial cells 
D) spleen 
A) bone marrow 
B) stem cells 
C) cells marginated on vessel endothelial cells 
D) spleen D

Question 2

What system is the "control center" for platelet activation?

Accepted Answer

A) eicosanoid (prostaglandin) pathway 
B) surface connect canalicular system 
C) membrane glycoproteins 
D) dense tubular system 
A) eicosanoid (prostaglandin) pathway 
B) surface connect canalicular system 
C) membrane glycoproteins 
D) dense tubular system D

Question 3

Which of the following is true of megakaryocytes as they mature?

Accepted Answer

A) nucleus becomes polyploid 
B) cytoplasmic basophilia becomes more pronounced 
C) size decreases 
D) nucleoli become more prominent 
A) nucleus becomes polyploid 
B) cytoplasmic basophilia becomes more pronounced 
C) size decreases 
D) nucleoli become more prominent A

Question 4

How many circulating platelets are produced from a single megakaryocyte?

Accepted Answer

A) 200-400 
B) 2000-4000 
C) 6000-8000 
D) 10,000-12,000 
A) 200-400 
B) 2000-4000 
C) 6000-8000 
D) 10,000-12,000

Question 5

Which of the following is the liver-secreted plasma enzyme that digests "unused VWF"?

Accepted Answer

A) ADP 
B) TXA2 
C) ADAMTS-13 
D) GPIb 
A) ADP 
B) TXA2 
C) ADAMTS-13 
D) GPIb

Question 6

Which of the following accurately describes reticulated (stress)platelets?

Accepted Answer

A) They appear in compensation for thrombocytopenia. 
B) They are smaller than mature circulating platelets. 
C) Their diameter exceeds 6 µm. 
D) Both a and c are true. 
A) They appear in compensation for thrombocytopenia. 
B) They are smaller than mature circulating platelets. 
C) Their diameter exceeds 6 µm. 
D) Both a and c are true.

Question 7

A platelet histogram can be generated using automated hematology analyzers,where frequency is plotted versus platelet volume.When a platelet histogram from a normal patient is examined,which of the following is true?

Accepted Answer

A) Distribution is gaussian. 
B) Mean platelet volume (MPV) is 14 fL. 
C) Distribution is log normal with a small population of large platelets. 
D) MPV is 5 fL. 
A) Distribution is gaussian. 
B) Mean platelet volume (MPV) is 14 fL. 
C) Distribution is log normal with a small population of large platelets. 
D) MPV is 5 fL.

Question 8

How are platelets released into peripheral circulation from the bone marrow?

Accepted Answer

A) Mature platelets squeeze between sinusoid endothelial cells. 
B) Megakaryocyte cytoplasmic fragments extend through the endothelial cells, lining the sinusoids, into blood and then shed platelets. 
C) Platelets adhere to white cells and exit with them. 
D) Megakaryocytes exit the marrow with white cells, and then platelets fragment off once they reach the blood. 
A) Mature platelets squeeze between sinusoid endothelial cells. 
B) Megakaryocyte cytoplasmic fragments extend through the endothelial cells, lining the sinusoids, into blood and then shed platelets. 
C) Platelets adhere to white cells and exit with them. 
D) Megakaryocytes exit the marrow with white cells, and then platelets fragment off once they reach the blood.

Question 9

Which of the following is not a function of the platelet surface-connected canalicular system (SCCS)?

Accepted Answer

A) produces energy for the cell 
B) delivers granule contents to the surface 
C) connects the internal contents to the surface 
D) stores hemostatic proteins 
A) produces energy for the cell 
B) delivers granule contents to the surface 
C) connects the internal contents to the surface 
D) stores hemostatic proteins

Question 10

Platelet agonists are substances that

Accepted Answer

A) bind to phospholipid in the platelet membrane. 
B) promote apoptosis. 
C) activate platelets. 
D) enhance megakaryocyte proliferation. 
A) bind to phospholipid in the platelet membrane. 
B) promote apoptosis. 
C) activate platelets. 
D) enhance megakaryocyte proliferation.

Question 11

Identify the platelet receptor and plasma protein required for normal platelet adhesion.
Platelet receptorPlasma protein
$\begin{array}{ll}
\underline { \text { Platelet receptor }} & \underline { \text { Plasma protein }} \
 \text { a. glycoprotein (GP) IV } & \text { factor VIII } \
\text { b. platelet factor } 4 \text { (PF4) } & \text { factor V } \
\text { c. gp IIb/IIa } & \text { fibrinogen } \
\text { d. gp Ib/IX/V } & \text { von Willebrand factor (VWF) }
\end{array}$

Accepted Answer

D
VWF must bind to i

Question 12

Which of the following megakaryocyte membrane markers disappears as differentiation proceeds?

Accepted Answer

A) CD34 
B) CD41 
C) CD42 
D) CD61 
A) CD34 
B) CD41 
C) CD42 
D) CD61

Question 13

Identify the platelet receptor and plasma protein required for normal platelet aggregation.
Platelet receptorPlasma protein
$\begin{array}{ll}
\underline { \text { Platelet receptor }} & \underline { \text { Plasma protein }} \
\text { a. GP IIb/IIIa }& \text { fibrinogen } \
\text { b. GP IV } & \text { factor VIII } \
\text { c. GP Ib/IX/V } & \text { VWF } \
\text { d. PF4 } & \text { factor V }
\end{array}$

Accepted Answer

A
Fibrinogen must bind to its

Question 14

Which of the following substances is stored in dense granules?

Accepted Answer

A) serotonin 
B) platelet factor 4 
C) fibronectin 
D) protein C inhibitor 
A) serotonin 
B) platelet factor 4 
C) fibronectin 
D) protein C inhibitor

Question 15

Phospholipids in the platelet membrane are important for all of the following functions except

Accepted Answer

A) supply of arachidonic acid. 
B) receptor for plasma fibrinogen. 
C) receptor for plasma coagulation enzymes. 
D) forms part of the platelet glycocalyx. 
A) supply of arachidonic acid. 
B) receptor for plasma fibrinogen. 
C) receptor for plasma coagulation enzymes. 
D) forms part of the platelet glycocalyx.

Exam 13: Platelet Production, Structure, and Function

From where are additional platelets first derived when the circulating count decreases?

What system is the "control center" for platelet activation?

Which of the following is true of megakaryocytes as they mature?

How many circulating platelets are produced from a single megakaryocyte?

Which of the following is the liver-secreted plasma enzyme that digests "unused VWF"?

Which of the following accurately describes reticulated (stress)platelets?

A platelet histogram can be generated using automated hematology analyzers,where frequency is plotted versus platelet volume.When a platelet histogram from a normal patient is examined,which of the following is true?

How are platelets released into peripheral circulation from the bone marrow?

Which of the following is not a function of the platelet surface-connected canalicular system (SCCS)?

Platelet agonists are substances that

Identify the platelet receptor and plasma protein required for normal platelet adhesion. Platelet receptorPlasma protein a. glycoprotein (GP) IV factor VIII b. platelet factor 4 (PF4) factor V c. gp IIb/IIa fibrinogen d. gp Ib/IX/V von Willebrand factor (VWF)

Which of the following megakaryocyte membrane markers disappears as differentiation proceeds?

Identify the platelet receptor and plasma protein required for normal platelet aggregation. Platelet receptorPlasma protein a. GP IIb/IIIa fibrinogen b. GP IV factor VIII c. GP Ib/IX/V VWF d. PF4 factor V

Which of the following substances is stored in dense granules?

Phospholipids in the platelet membrane are important for all of the following functions except

An Overview of Clinical Laboratory Hematology

Safety in the Hematology Laboratory

Blood Specimen Collection

Care and Use of the Microscope

Quality Assurance in Hematology and Hemostasis Testing

Cellular Structure and Function

Hematopoiesis

Erythrocyte Production and Destruction

Erythrocyte Metabolism and Membrane Structure and Function

Hemoglobin Metabolism

Iron Kinetics and Laboratory Assessment

Leukocyte Development, Kinetics, and Functions

Manual, Semiautomated and Point-of-Care Testing in Hematology

Automated Blood Cell Analysis

Examination of the Peripheral Blood Film and Correlation with the Complete Blood Count

Bone Marrow Examination

Body Fluid Analysis in the Hematology Laboratory

Anemias: Red Blood Cell Morphology and Approach to Diagnosis

Disorders of Iron Kinetics and Heme Metabolism

Anemias Caused by Defects of DNA Metabolism

Bone Marrow Failure

Introduction to Increased Destruction of Erythrocytes

Intrinsic Defects Leading to Increased Erythrocyte Destruction

Extrinsic Defects Leading to Increased Erythrocyte Destruction Nonimmune Causes

Extrinsic Defects Leading to Increased Erythrocyte Destruction Immune Causes

Hemoglobinopathies (Structural Defects in Hemoglobin)

Thalassemias

Nonmalignant Leukocyte Disorders

Cytogenetics

Molecular Diagnostics in Hematopathology

Flow Cytometric Analysis in Hematologic Disorders

Myeloproliferative Neoplasms

Myelodysplastic Syndromes

Acute Leukemias

Mature Lymphoid Neoplasms

Normal Hemostasis and Coagulation

Hemorrhagic Disorders and Laboratory Assessment

Thrombotic Disorders and Laboratory Assessment

Thrombocytopenia and Thrombocytosis

Qualitative Disorders of Platelets and Vasculature

Laboratory Evaluation of Hemostasis

Antithrombotic Therapies and their Laboratory Assessment

Hemostasis and Coagulation Instrumentation

Pediatric and Geriatric Hematology and Hemostasis

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