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Hematology > Hema Lec #2: Platelet Structure, Function and Kinetics > Flashcards

Hema Lec #2: Platelet Structure, Function and Kinetics Flashcards

1
Q

what is the other name for platelets?

A

thrombocytes

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2
Q

All describe thrombocyte except:

a. nucleated blood cells that circulate in the blood, originate from megakaryocytes’ chromatin in a process called platelet-shedding
b. nucleated blood cells that circulate in the blood, originate from megakaryocytes’ cytoplasm in a process called platelet-shedding
c. non-nucleated blood cells that does not circulate in the blood, originate from megakaryocytes’ cytoplasm in a process called platelet-shedding
d. non-nucleated blood cells that circulate in the blood, originate from megakaryocytes’ cytoplasm in a process called thrombopoiesis

A

d. non-nucleated blood cells that circulate in the blood, originate from megakaryocytes’ cytoplasm in a process called thrombopoiesis

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3
Q

what is the normal platelet range of an adult

A

150-450 x10 9/L

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4
Q

where does the additional one third of platelets sequestered?

A

spleen

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5
Q

In splenomegaly or hypersplenism, increased sequestration may cause

a. relative thrombocytopenia
b. relative thrombocytosis
c. none of the above
d. all of the above depende sabot

A

a. relative thrombocytopenia

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6
Q

what is the life span of mature platelet?

A

8-10 days

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7
Q

the marrow transit time from a megakaryocyte to a platelet is approximately

A

5 days

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8
Q

In a standard Wright-stained blood film, the average is about …

A

2.5 mm in diameter

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9
Q

what is the mean platelet volume range

A

8 to 10 fL

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10
Q

what is the other name for reticulated platelets?

A

stress platelets

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11
Q

Which of the following that does not describe stress platelet?

a. Appear in compensation for thrombocytopenia. it is markedly larger than ordinary platelets
b. it carry free ribosomes and fragments of rough endoplasmic reticulum
c. it is potentially prothrombic and may be associated with increased risk of cardiovascular disease
d. Appear in compensation for thrombocytosis. it is markedly larger than ordinary platelets

A

d. Appear in compensation for thrombocytosis. it is markedly larger than ordinary platelets

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12
Q

Reticulated platelets are identified via dye for nucleic acid. Give example of dye

A

Thiazole orange

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13
Q

T/F. Stress platelet may be associated with increased risk of cardivascular disease.

A

true

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14
Q

What are the two peropheral zone in Platelet Ultrastructure?

A

Glycocalyx and Plasma membrane

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15
Q

what is the other name for glycocalyx?

A

fluffy coat

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16
Q

What peripheral zone surrounds the cellular membrane

A

glycocalyx

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17
Q

All but one are true about fluffy coat

a. it is composed of plasma proteins and carbohydrate molecules that acts as glycoprotein receptor
b. it mediate platelet adherence and platelet aggregation
c. 20-50 thick
d. it mediate change of shape, internal contraction

A

c. 20-30 thick

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18
Q

All but one describe plasma membrane

a. selectively impermeable and is composed of bilayer of phospholipids
b. selectively permeable and is composed of bilayer of phospholipids
c. none of the above
d. Anchored glycoproteins supports essential plasma surface-oriented glycosylated receptors that respond to cellular and humoral stimuli, called agonist.

A

a. selectively impermeable and is composed of bilayer of phospholipids

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19
Q

What is the other name for open canalicular system?

A

surface-connected canalicular system

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20
Q

it is a series of random plasma membrane invaginations into the platelet interior

A

open canalicular system

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21
Q

In close proximity to granules especially alpha granules?

A

open canalicular system

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22
Q

it is the route of release of granule contents to the plateler’s exterior microenvironment?

A

open canalicular system

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23
Q

a “control center” for platelet activation

A

Dense tubular system

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24
Q

composed of condensed remnant of the rough ER

A

Dense tubular system

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25
Q

T/F. Dense tubular system sequesters carbohydrate and enzyme that support platelet activation.

A

False. Calcium

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26
Q

What are the enzymes in DTS that support the platelet activation through the production of thromboxane A2

A

thromboxane synthase, phospholipase A2 and cyclooxygenase

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27
Q

What is the enzymes in DTS that support the production of inositol triphosphate and diaglycerol?

A

Phospholipase C

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28
Q

A platelet cytoskeleton that maintains the platelet’s discoid shape

A

microtubules

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29
Q

T/F. During platelet activation, microtubules move outward to enable the expression of alpha-granule contents

A

False. Inward

30
Q

A cytoskeletal proteins found in between the microtubular layer and plasma membrane

A

Actin meshwork

31
Q

A contractile protein

A

Actin

32
Q

other cytoskeletal proteins that help control platelet shape change, extension of pseudopods and the secretion of granule contents

A

intermediate filaments, polymers of desmin and vimentin

33
Q

Which of the following that best describe Alpha-Granules?

a. Most abundant granules that stained black in transmission electron microscopy
b. filled with endocytosed proteins; some synthesized within the megakaryocytes and stored in platelet
c. Most abundant granules that stained black in transmission phase contrast microscopy
d. none of the above

A

b. filled with endocytosed proteins; some synthesized within the megakaryocytes and stored in platelet

34
Q

T/F. Alpha granules are most abundant granules approx. 50 to 80 granules in each platelet. It stained black in transmission electron microscopy

A

False. Dark gray

35
Q

Name the alpha granule proteins in which their properties is for adhesion molecule

A

fibronectin and Thrombospondin

36
Q

Name the alpha granule proteins in which their properties is for fibrinolysis promotion

A

Plasminogen

37
Q

Name the alpha granule proteins in which their properties is for Fibrinolysis control

A

Plasminogen activator inhibitor- 1 and alpha 2- Antiplasmin

38
Q

Name the alpha granule proteins in which their properties is for coagulation control

A

Protein C inhibitor

39
Q

Name the alpha granule proteins in which their properties is for heparin neutralization, suppresses megakaryocytopoiesis

A

Platelet factor 4

40
Q

Name the alpha granule proteins in which their properties supports mitosis of vascular fiboblasts and smooth muscle cells

A

Platelet-derived growth factor
Endothelial growth factor
Transforming growth factor-Beta

41
Q

Name the alpha granule proteins in which their properties that found nowhere nut platelet alpha-granules

A

Beta-thromboglobulin

42
Q

Which of the following is true about Dense Granules/Dense Bodies?

a. Appear before alpha granules in megakaryocytic differentiation
b. Stain Dark gray in electron microscopy
c. Migrate to the plasma membrane and release their contents directly into the plasma microenvironment upon platelet activation
d. none of the above

A

c. Migrate to the plasma membrane and release their contents directly into the plasma microenvironment upon platelet activation

43
Q

A Dense granule contents that is a vasoconstrictor that binds endothelial cells and platelet membranes

A

Serotonin

44
Q

A Dense granule contents that is divalent cations support platelet activation and coagulation

A

Calcium and Magnesium

45
Q

A Dense granule contents that is their functionare unknown, but ATD release is detectable upon platelet activation

A

ATP

46
Q

A Dense granule contents that is nonmetabolic, supports neighboring platelet aggregation by binding to ADP receptors P2Y1, P2Y2

A

ADP

47
Q

Name the Platelet Granules

A

apha-granules
dense granules
lysosomes

48
Q

T/F. Platelets are metabolically active that needs energy for metabolic activities and cellular contraction that enable the granules to release their contents

A

True

49
Q

T/F. The energy in Platelet is derived from anaerobic metabolism in the mitochondria and aerobic glycolysis utilizing glycogen stores.

A

False. aerobic metabolism in mitochondria and anaerobic glycolysis utilizing glycogen stores

50
Q

All but one describe the functions of platelet

a. Maintain the physical integrity of the vascular endothelium and Form platelet plugs
b. all of the above
c. participate in endothelial repair through the contribution of platelet-derived growth factor (PDGF)
d. Promote the coagulation cascase through platelet phospholipid complex

A

b. all of the above

51
Q

All but one refers to the platelet functions:

a. Maintain the physical integrity of the vascular endothelium
b. participate in endothelial repair through the contribution of platelet-derived growth factor (PDGF)
c. promote coagulation cascade and form platelet plugs
d. all of the above
e. none of the above

A

e. none of the above

52
Q

What substance that become the substrate for COX1?

A

arachidonic acid

53
Q

COX1 converts arachidonic acid into ….

A

prostaglandin h2

54
Q

what enzyme that acts on prostaglandin H2 to produce another substance that mobilizes calcium from the DTS land increasing cytoplasmic levels?

A

Thromboxane synthetase

55
Q

What substance produced when an enzyme acts on prostaglanding H2?

A

thromboxane 2

56
Q

What substance produced when an enzyme acts on prostaglanding H2?

A

thromboxane 2

57
Q

What subtance that mobilize calcium and increasing cytoplasmic calcium levels causing contraction of actin microfilaments

A

thromboxane 2

58
Q

What pathway that ends in production of prostacyclin?

A

Eicosanoid pathway

59
Q

A substance that encourages calcium sequestration in the DTS

A

prostacyclin

60
Q

T/F. Eicosanoid pathway acts after cyclooxygenase pathway.

A

False. acts the same time

61
Q

What enzyme that acted upon arachidonic acid and gets converted into prostaglandins, prostacyclin, and thromboxane

A

COX2

62
Q

All but one refers to Prostacyclin:

a. most important prostanoid
b. most potent endogenous inhibitor of platelet aggregation
c. Has the same effect of TXA2
d. doesn’t want the calcium to be released

A

c. Has the same effect of TXA2

63
Q

When collagen bids to platelet GPVI, internal platelet activation pathways are triggered, resulting in the release of …

A

thromboxane A2 and adenosine diphosphate (ADP)

64
Q

T/F. The combined effect of GP1b/IX/V and GPVI and VWF and collagen causes the platelet to become firmly affixed to the damaged surface, where it the loses its discoid shape

A

true

65
Q

T/F. TXA2 and ADP secreted to the microenvironment from thrombocyte, where they activate neighboring platelets to firmly affixed to the damage surface

A

False. activate neighboring platelets so aggregation can proceed

66
Q

Which of the following that does not define liver-secreted enzyme?

a. VWF-cleaving protease
b. Digests “unused” VWF
c. Platelet GP1B-VWF interactions remained localized by this enzyme
d. Facilitates platelet adhesion

A

d. Facilitates platelet adhesion

67
Q

T/F. The VWF-GP1b tethering reaction is permanent until GPVI binds to type 1 collagen

A

False. temporary

68
Q

A peptide sequence present in the fibrinogen that mediates the binding to GP IIB/IIIA

A

Arginine-glycine-aspartic acid

69
Q

What platelet functions that refers to the key part of primary hemostasis

A

platelet aggregation

70
Q

A disorder of primary hemostasis that inherits mutation of platelet Glycoprotein in Ib-Iv-V comples

A

Bernard-soulier Syndrome

71
Q

A disorder of primary hemostasis that has abnormal platelet membrane glycoprotein IIb/IIIA preventing adequate platelet aggregation

A

Glanzmann Thrombasthenia

Hematology (18 decks)

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