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mtap 2 - hema (readings) > Chap 10: Platelet Production, Structure and Function > Flashcards

Chap 10: Platelet Production, Structure and Function Flashcards

1
Q

Nonnucleated blood cells that circulate at a concentration of 150 to 400 x10^9/L

A

Platelets

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2
Q

Platelets that arise from unique bone marrow cells are called

A

Megakaryocytes

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3
Q

Are the largest cells in the bone marrow and possess multiple chromosome copies (polyploid)

A

Megakaryocytes

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4
Q

Megakaryocytes account for less than what percentage of all bone marrow cells?

A

0.5%

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5
Q

Responding to the growth factor thrombopoietin (TPO), megakaryocyte progenitors are recruited from

A

Common myeloid progenitors

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6
Q

T/F: Megakaryocytes are also found in the lungs

A

TRUE

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7
Q

Megakaryocyte progenitors arise from the common myeloid progenitor under the influence of what transcription gene product?

A

GATA-1 regulated by cofactor FOG1

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8
Q

GATA-1 stands for

A

Globin transcription factor-1

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9
Q

FOG1 stands for

A

“Friend of GATA” (a product of the ZFPM1 (zinc finger protein multitype 1) gene)

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10
Q

Three megakaryocyte lineage-committed progenitor stages, defined by their in vitro culture colony characteristics arise from

A

Common Myeloid Progenitor

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11
Q

Least mature progenitor

A

Burst-forming unit (BFU-Meg)

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12
Q

Intermediate progenitor

A

Colony-forming unit (CFU-Meg)

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13
Q

More mature progenitor

A

Light-density CFU (LD-CFU-Meg)

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14
Q

These two are diploid and undergo normal mitosis to maintain a viable pool of megakaryocyte progenitor

A

BFU-Meg and CFU-Meg

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15
Q

All three progenitor stages resemble lymphocytes and CANNOT be distinguished by

A

Wright-stained light microscopy

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16
Q

Undergoes endomitosis

A

LD-CFU-Meg

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17
Q

A partially characterized form of mitosis unique to megakaryocytes in which DNA replication and cytoplasmic maturation are normal but cells lose their capacity to divide

A

Endomitosis

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18
Q

Forrm of mitosis that lacks telophase and cytokinesis (separation into daughter cells)

A

Endomitosis

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19
Q

Megakaryocyte progenitors leave the proliferative phase and enter

A

Terminal differentiation

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20
Q

Series of membrane-lined channels that invade from the plasma membrane and grow inward to subdi- vide the entire cytoplasm

A

Demarcation System (DMS)

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21
Q

Biologically identical to the megakaryocyte plasma membrane and ultimately delineates the individual platelets during thrombocytopoiesis.

A

Demarcation System (DMS)

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22
Q

Nuclear lobularity first becomes apparent as an indentation at the 4N replication stage, rendering the cell identifiable as an

A

MK-II stage, or promegakaryocyte

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23
Q

Ploidy levels are measured using _, a nucleic acid dye in megakaryocyte flow cytometry

A

Propidium iodide

24
Q

The process of platelet shedding

A

Thrombocytopoiesis

25
Q

A single megakaryocyte may shed

A

2000 t0 4000 platelets

26
Q

Lifespan of platelets

A

8-9 days

27
Q

First to appear on megakaryocyte progenitors and remains present throughout maturation

A

CD34 marker (along with CD36, CD42 and CD62)

28
Q

A viral oncogene associated with murine myeloproliferative leukemia.

A

MPL

29
Q

T/F: The plasma concentration of TPO is inversely proportional to platelet and megakaryocyte mass

A

TRUE

30
Q

Elevate the platelet count in patients being treated for a variety of cancers, including acute leukemia.

A

Synthetic TPO Mimetics

31
Q

A nonimmunogenic oligopeptide that is effective in raising the platelet count in patients with chronic immune thrombocytopenic purpura (ITP)

A

Commercial TPO mimetic, romiplostim (NPlate, Amgen)

32
Q

Cytokines that function with TPO to stimulate mega- karyocytopoiesis include

A

IL-3, IL-6 and IL-11

32
Q

Cytokines that function with TPO to stimulate mega- karyocytopoiesis include

A

IL-3, IL-6 and IL-11

33
Q

Factors inhibit in vitro megakaryocyte growth, which indicates that they may have a role in the control of megakaryocytopoiesis in vivo

A

Ptelet factor 4 (PF4), B-thromboglobulin, neutrophil- activating peptide 2, IL-8,

34
Q

Sometimes known as stress platelets, appear in compensation for thrombocytopeni

A

Reticulated platelets

35
Q

Essential plasma surface-oriented glycosylated receptors that respond to cellular and humoral stimuli

A

Ligands or agonists

36
Q

The plasma membrane surface that absorbs albumin, fibrinogen, and other plasma proteins, in many instances transporting them to internal storage organelles using a process called endocytosis

A

Glycocalyx

37
Q

The plasma membrane invades the platelet interior, producing a unique _

A

Surface-connected canalicular system (SCCS

38
Q

A condensed remnant of the rough reticulum

A

Dense tubular system (DTS)

39
Q

DTS sequesters Ca2􏰆 and bears a number of enzymes that support platelet activation including

A

Phospholipase A2, cyclooxygenase, and thromboxane synthetase

40
Q

Contractile in platelets (as in muscle) and anchors the plasma membrane glycoproteins and proteoglycans

A

Actin

41
Q

Granules that are filled with proteins, some endocytosed, some synthesized within the mega- karyocyte and stored in platelets

A

Alpha granules

42
Q

An integrin that binds the subendothelial collagen that becomes exposed in the damaged blood vessel wall, promoting adhesion of the platelet to vessel wall

A

A2B1

43
Q

A key collagen receptor that also binds the adhesive protein thrombospondin

A

GP IV

44
Q

Leucine-rich-repeat family CAM

A

GP Ib/IX/V

45
Q

These platelet “agonists” are ligands for seven-transmembrane repeat receptors (STRs), so named for their unique membrane- anchoring structure

A
  • Thrombin
  • Thrombin receptor activation peptide (TRAP),
  • Adenosine diphosphate (ADP),
  • Epinephrine
  • Serotonin,
  • Thromboxane A2 (TXA2)
  • Other prostaglandins)
46
Q

Leads to an increase in intracellular calcium levels and contributes to initial platelet activation, shape change, and the formation of small reversible aggregates

A

P2Y1 signaling

47
Q

Leads to a decrease in cyclic adenosine monophosphate (cAMP) levels and supports the formation of irreversible plate- let aggregates

A

P2Y12

48
Q

A low-affinity receptor for the immunoglobulin Fc portion that plays a role in a dangerous condition called heparin-induced thrombocytopenia

A

FcyIIA (CD32)

49
Q

An integrin that facilitates platelet binding to endothelial cells, leukocytes, and one another

A

P-selectin (CD62)

50
Q

Platelet aggregation is a key part of primary hemostasis, which in arteries may end with the formation of a

A

White clot

51
Q

White clot is composed primarily of

A

Platelets and vWf

52
Q

Fibrin and red blood cells deposit around and within the platelet syncytium to form a bulky

A

Red clot

53
Q

Red clot is essential to wound repair, but it may also be characteristic of inappropriate coagulation in venules and veins, resulting in

A

Deep vein thrombosis and pulmonary embolism

54
Q

The polar phospholipid on which the factor IX/VIII (tenase) and factor X/V (prothrombinase) complexes assemble

A

Phosphatidylserine

55
Q

Are membrane-derived vesicles that form in response to an activating stimulus that increases the platelet intracellular concentration of calcium

A

Microparticles

mtap 2 - hema (readings) (2 decks)

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