Question 1

The normal reference interval for the mean platelet volume (MPV) is:

Accepted Answer

The normal reference interval for MPV is 6.8-10.2 fL. Option A is the reference interval for hemoglobin, option B is the reference interval for platelet count, and option C is the reference interval for platelet concentration.

Question 2

Which of the following criteria describes giant platelets?

Accepted Answer

Giant platelets are defined as platelets that are greater than 5 mcM in size.

Question 3

Describe megakaryocyte development and the role of endomitosis and thrombopoietin in this process.

Accepted Answer

Platelets develop from megakaryocytes. Megakaryocyte maturation is produced through endomitosis. Endomitosis differs from mitosis in that it is missing telophase. As a result, nuclear duplication occurs without nuclear or cytoplasmic division. The resulting maturing cells are larger than in the previous stage. MK1 is smaller than MK2, which is smaller than MK3, which is smaller than MK4. The stages are very large (can reach up to 150 mcM [µm]), and can be easily spotted under low power when examining bone marrow specimens. These respond to changes in thrombopoietin. Thrombopoietin interacts with c-MPL receptor on the megakaryocytes to induce thrombopoiesis and speed up the maturation time of the megakaryocyte. Mature platelets bud off the megakaryocyte and enter the circulation.

Question 4

Platelets play a major role in forming the primary hemostatic plug by all of the following actions except:

Accepted Answer

Platelets do not have the ability to lyse or break down clots, they actually promote clot formation through adhesion, activation, and secretion of various clotting factors.

Question 5

During what stage of megakaryocyte development are the platelets released into the circulation?

Accepted Answer

The platelets are released into circulation during the proplatelet formation stage of megakaryocyte development. Proplatelets are long, branching cytoplasmic extensions that protrude into the blood vessels, and they eventually form the mature platelets.

Question 6

Explain how platelets contribute to :
a. The innate immune response
b. The adaptive immune response

Accepted Answer

The answer of Explain how platelets contribute to :
a. The...

Question 7

Which of the following cells is defined as cytoplasmic extensions that are released in groups and fragmented into individual platelets?

Accepted Answer

The answer of Which of the following cells is defined...

Question 8

Nuclear replication without cytoplasmic division is defined as:

Accepted Answer

Nuclear replication without cytoplasmic division is called endomitosis. Asynchrony refers to cells division that occurs at different times or rates. Dysmyelopoiesis refers to abnormal development of bone marrow cells that produce blood cells. Hematopoiesis refers to the formation and development of blood cells. None of these terms describe nuclear replication without cytoplasmic division.

Question 9

What is the typical concentration of platelets in the blood?

Accepted Answer

The typical concentration of platelets in the blood is 150-450 x 10^9/L.

Question 10

The effect of thrombopoietin (TPO) on megakaryocytic cells can be described by all of the following except:

Accepted Answer

Thrombopoietin (TPO) actually promotes proliferation of megakaryocytic cells, so it does not inhibit proliferation as stated in choice B. Choices A, C, and D are all true statements about the effect of TPO on megakaryocytic cells.

Question 11

Platelets are derived from which of the following?

Accepted Answer

Platelets are derived from megakaryocytes, which are large bone marrow cells that break up into thousands of fragments to form platelets.

Question 12

Which of the following represents a normal platelet number and morphology?

Accepted Answer

Normal platelets range between 150,000 to 400,000 platelets per microliter of blood. The platelets in Option C are closest to this range with a blood concentration of 250 10⁹/L and a size of 2.5 mcM. The platelets in the other options either have an abnormal size, abnormal concentration, or both.

Question 13

On average, how long does a platelet live in the peripheral circulation?

Accepted Answer

Platelets typically have a lifespan of about 7 to 10 days in the peripheral circulation.

Question 14

Laboratory results for a patient indicate that the platelet count is 89 × 10⁹/L. What is likely to be observed in the peripheral blood for this patient if the platelet count is the result of increased physiological platelet destruction?

Accepted Answer

Reticulated platelets are immature platelets released into circulation in response to increased platelet destruction. Megakaryocytes, megakaryoblasts, and megathrombocytes are all immature or precursor cells that are not typically observed in peripheral blood.

Question 15

Increased DNA content in exact multiples that are contained within a single nuclear envelope defines cells that are:

Accepted Answer

Polyploid cells have increased DNA content in exact multiples of the haploid genome that are contained within a single nuclear envelope. Proliferating cells can have increased DNA content due to the replication of the genome during cell division, but this does not necessarily result in polyploidy. Apoptotic cells undergo programmed cell death and may have fragmented DNA, but not necessarily increased DNA content. Differentiated cells can have different levels of DNA content compared to their undifferentiated counterparts, but this does not necessarily indicate polyploidy.

Question 16

Which of the following describes how platelet clumping artificially alters platelet parameters?

Accepted Answer

Platelet clumping artificially increases both the Platelet Distribution Width (PDW) and the Mean Platelet Volume (MPV) because the clumps are counted as large platelets, thus increasing the average size and variability of the platelet measurements.

Question 17

Which of the following cytokines stimulate progenitor megakaryocytes to proliferate?

Accepted Answer

TPO (Thrombopoietin) and GM-CSF (Granulocyte-Macrophage Colony-Stimulating Factor) are key cytokines involved in the proliferation of progenitor megakaryocytes, which are cells that give rise to platelets.

Question 18

Identify the major cytokines that regulate platelet production and describe their effects on megakaryocytic cells and circulating platelets.

Accepted Answer

The answer of Identify the major cytokines that regulate platelet...

Quiz 9: The Platelet