Platelet Structure And Function Flashcards

1
Q

Where are megakaryocytes found?

A

Only in bone marrow and not in peripheral blood

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2
Q

Largest cell in the bone marrow

A

Megakaryocytes

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3
Q

Megakaryocyte mission is to proliferate and release fragments of _____________ Into circulation. 

A

Cytoplasm (Platelets) 

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4
Q

 Megakaryocytopoiesis Is controlled by growth factors such as….

A

Interleukins and thrombopoietin (TPO, a renal hormone)

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5
Q

From the kidneys (Also from liver and spleen) Is a major growth factor for megakaryocytic progenitor cells to mature and release Platelets

A

Thrombopietin (TPO) 

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6
Q

What is the old name for platelets?

A

Thrombocytes

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7
Q

What is the normal platelet range? 

A

150 to 450,000 µL

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8
Q

Where are megakaryoblasts or MK-I found? 

A

In bone marrow only

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9
Q

megakaryoblasts or MK-I nucleus undergoes __________. 

A

Endomitosis

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10
Q

megakaryoblasts (MK-I) nucleus…

A

Overlapping nuclear lobes (Can only see one)

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11
Q

megakaryoblasts (MK-I) cytoplasm…

A

Contain scanty, blue cytoplasm, and no granules yet*

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12
Q

megakaryoblasts (MK-I) N:C ratio is _______

A

High

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13
Q

megakaryoblasts (MK-I) size?

A

14 to 18 micrometers

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14
Q

can megakaryoblasts (MK-I) be classified by visual morphology? 

A

No! Cannot be classified by visual morphology alone! 

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15
Q

How to Promegakaryocytes (MK-2) composite to megakaryoblasts (MK-I) in size?

A

Larger (14 to 30 µm) 

  • an exception to the rule that older cells get smaller
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16
Q

Promegakaryocytes (MK-2) nucleus…

A

Becomes lobulated or indented

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17
Q

Promegakaryocytes (MK-2) N:C ratio?

A

Moderate 

18
Q

Promegakaryocytes (MK-2) cytoplasm?

A

Begins to develop dense, alpha and lysosomal granules (Red-pink)

19
Q

Promegakaryocytes (MK-2):

demarcating membrane system (DMS) develops; Importance?

A

Forms eventual “perforations” where platelets break off

20
Q

The largest cell in the bone marrow? What’s the size? 

A

Basophilic/granular megakaryocyte (MK-3)

16 to 56 µm

21
Q

Basophilic/granular megakaryocyte (MK-3) N:C ratio?

A

Moderate

22
Q

Basophilic/granular megakaryocyte (MK-3) nucleus…

A

Intensely lobulated

23
Q

Basophilic/granular megakaryocyte (MK-3) cytoplasm…

A

Has distinct granulation (Eosinophilic and granular)

24
Q

what do Basophilic/granular megakaryocyte (MK-3) have on their surface?

A

Various platelet specific receptors expressed

25
Q

At what stage is shedding of platelets?

A

Mature megakaryocyte

26
Q

Mature megakaryocyte nucleus….

A

Multi lobed nucleus

27
Q

Mature megakaryocyte N:C ratio?

A

Low

28
Q

Mature megakaryocyte cytoplasm…

A

-basophilia of cytoplasm has disappeared
-pink granules in the cytoplasm are now clustered into small aggregates called platelet fields

29
Q

Pink granules in the cytoplasm of mature megakaryocytes that cluster into small aggregates are called….

A

Platelet fields

30
Q

Mature Megakaryocytes buds/sheds between ____________ cytoplasmic Fragments which become the platelets

A

2000 to 4000

31
Q

Maturation time from blast stage to platelet formation is typically _____ days. 

A

5

32
Q

Normal marrow contains approximately __________ Megakaryocytes

A

15 million

33
Q

Normal circulation life of a platelet is ______ days 

A

8 to 10

34
Q

Platelets are removed or destroyed by ______________ In the liver and spleen, or by active use. 

A

Macrophages

35
Q

Circulating platelets are distributed between the spleen and blood. What proportion is always in the spleen? 

A

1/3

36
Q

Under normal conditions, the platelet count or mass is consistent even with active use. What does this indicate?

A

A feedback system adjust production to consumption

37
Q

_______ stimulates production of platelets

A

TPO

38
Q

___________ activates platelets.

A

Thrombin

39
Q

A single megakaryocyte may shed _________ Platelets

A

2000 to 4000

40
Q

___________ is the primary serine protease of coagulation. 

A

Thrombin