Blood Platelets (Thrombocytes)

Question 1

Number of Platelets:

Answer 1

150.000- 400.000/mm³.

Question 2

 Increase in number of Platelets: :

Answer 2

Thrombocytosis

Question 3

Decrease in number of Platelets: :

Answer 3

Thrombocytopenia

Question 4

Life span of Platelets:

Answer 4

10 days

Question 5

Senescent platelets are phagocytosed

by macrophages primarily in the…………

Answer 5

spleen

Question 6

The platelets are cell fragments derived
from the………………………….. in the bone
marrow.

Answer 6

megakaryocytes

Question 7

Size of Platelets

Answer 7

2 - 4 µm in diameter.

Question 8

 Shape of Platelets

Answer 8

oval disk shaped (cell fragments).

Question 9

Nucleus of Platelets

Answer 9

They lack nuclei.

Question 10

Peripheral clear region of Cytoplasm of Platelets

Answer 10

Hyalomere

Question 11

Central granular region of Cytoplasm of Platelets

Answer 11

Granulomere

Question 12

Marginal bundle consisting of:

………………..microtubules arranged parallel to each other forming a ring within the hyalomere.

Answer 12

10 -15

Question 13

…………………………… assist in maintaining the discoid form of the platelets

Answer 13

microtubules

Question 14

………………………………. helping contraction of the platelets during retraction of blood clot

Answer 14

Actin and myosin microfilaments

Question 15

Granulomere:
Alpha granules (majorty)

Answer 15

• Fibrinogen
• PDGF
• coagulation factors.
• Platelet factor 4.

Question 16

Delta granules

Answer 16

• ADP
• ATP
• Ca
• Serotonin

Question 17

Lambda granule

Answer 17

Lysosomes

Question 18

Megakaryoblast (Immature megakaryocyte)

• Size…………….
• Nucleus:………………
• Cytoplasm: …………………….

Answer 18

• Size: large cell 25-50μm.
• Nucleus: large with numerous
  nucleoli.
• Cytoplasm: highly basophilic homogenous non-granular.

Question 19

Megakaryoblast (Immature megakaryocyte)
- Before differentiation, they undergo …………………, with repeated rounds of …………………………………………… not
separated by cell divisions, resulting in a nucleus that is………………………………………………………..

Answer 19

• endomitosis
• DNA replication
• highly polyploid

Question 20

Megakaryocyte (mature cell)

• Size:…………………..
• Nucleus:……………
• Cytoplasm:……………………..

Answer 20

• Size: a giant cell up to 150 μm
• Nucleus: large lobulated and polyploid.
  -Cytoplasm: basophilic - granular.
  -It contains numerous mitochondria, well
  developed rER, extensive Golgi complex, α
  granules, lysosomes (lambda granules) and
  dense bodies.

Question 21

Megakaryocyte (mature cell)

Answer 21

• Is a giant cell
• Nucleus is large lobulated & deeply stained.
• Cytoplasm is basophilic.