Platelet structure and formation

Question 1

Platelets derived from

Answer 1

Megakaryocytes

Question 2

Function of platelets

Answer 2

Hemostasis

Question 3

Shape of inactivated platelets

Answer 3

biconvex

Question 4

size of platelets

Answer 4

2-3 micrometers in diameter

Question 5

Hormone that regulates megakaryocyte and platelet formation

Answer 5

Thrombopoietin

Question 6

Thrombopoietin is produced by

Answer 6

liver and kidney

Question 7

How many platelets does one megakaryocyte produce

Answer 7

1000-3000

Question 8

How many platelets are produced in an adult in a day

Answer 8

10 raised to the power 11

Question 9

Percentage of platelets stored in the spleen at any point in time

Answer 9

30-40%

Question 10

Why does splenic contraction occur

Answer 10

To release sequestered platelets through induction by sympathetic system

Question 11

Why do sickle cell patient have higher platelet count

Answer 11

By the time they reach their teens, they undergo autosplenectomy hence platelets are released into the circulation

Question 12

Average lifespan of circulating platelet

Answer 12

8-10 days

Question 13

How are platelets destroyed

Answer 13

By phagocytosis by the reticular activating system

Question 14

How many lobes does megakaryocyte have

Answer 14

multiple lobed

Question 15

When is a megarkaryocyte said to be active

Answer 15

When it has tiny dots or platelets present on it

Question 16

How many zones are platelets seperated into

Answer 16

4.

Peripheral zone
Sol gel zone
Membranous zone
organelle zone

POMS

Question 17

What do you find in the peripheral zone

Answer 17

It has glycoproteins required to platelet adhesion, aggregation, activation

Question 18

Sol gel zone contains

Answer 18

Microfilaments and microtubules which maintain discoid shape of platelet.

Question 19

Under what conditions do platelets turn round

Answer 19

Under cold conditions when microfilaments dissasemble.

Under warm conditions they go back to their original shape

Question 20

Membranous zone contains

Answer 20

Membranes derived from the smooth endoplasmic reticulum of megakaryocytic cells.

These membranes form a tube to the surface of the platelet membrane and synthesize and release thromboxane A2

Question 21

Organelle zone contains

Answer 21

2 types of platelet granules.

1. Alpha granules which contain clotting factors like factor V,VIII, Fibrinogen
2. Delta granules or dense bodies ; Contain ADP, calcium. serotonin which are platelet activating mediators

Question 22

Normal platelet count

Answer 22

150-450 times 10 raised to the power 9 L

Question 23

Thrombocytopenia

Answer 23

Low platelet count

< 150 TIMES TEN RAISED TO THE POWER 9 L

Question 24

Causes of thrombocytopenia( Not producing enough)

Answer 24

Bone marrow faluire
Hereditary
Marrow infiltration
Chemotherapy
Radiation therapy

Question 25

Causes of Increased destruction of platelets

Answer 25

``` Immune thrombocytopenic purpura ( autoantibodies against platelets) DIC Von willebrands disease type 2b Heparin induced Mechanical destruction Neonatal alloinduced thrombocytopenia ```

Question 26

Other causes of thrombocytopenia

Answer 26

``` hypersplenism drugs gestational-Increased plasma volume will affect platelets infections Hemophagocytosis ```

Question 27

Thrombocytosis

Answer 27

Increased platelet count

Question 28

Types of thrombocytosis

Answer 28

Primary | Secondary- due to a disease

Question 29

Causes of primary thrombocytosis

Answer 29

``` Polycythemia vera myelofibrosis myelodysplastic syndromes chronic myeloid leukemia essential thrombocytosis ```

Question 30

Secondary thrombocytosis

Answer 30

``` infection inflammatory disorders Acute/ chronic blood loss tissue damage from trauma/surgery medicines splenectomy malignancy rebound from chemotherapy ```

Question 31

Spurious platelet counts

Answer 31

A situation where full blood count will give a false low or high platelet count

Question 32

Causes of false thrombocytosis

Answer 32

Anything that causes red cell fragmentation so machine counts it as smaller sized platelets burns microangiopathic hemolytic anemia Microorganisms Fragments of white cells in patients with leukemia

Question 33

Causes of false thrombocytopenia

Answer 33

Platelet aggregation by EDTA, myeloma etc. Larger than normal platelets Platelet satellitism where they surround WBCs and are counted as one