Thrombopoiesis

Question 1

What protein do platelets interact with to form the first barrier to blood loss

Answer 1

von Willebrands Factor

Question 2

What does platelet aggregration form?

Answer 2

thrombus

Question 3

What 4 things do platelets do that help create a barrier to blood loss?

Answer 3

1. Provide negatively charged surface to support coagulation
2. Localised thrombus formation
3. Promotes vasoconstriction
4. Promotes vessel repair

Question 4

Steps in thrombopoiesis.

Answer 4

1. Megakaryoblast
2. Promegakaryocyte
3. Megakaryocyte
4. Platelets (produced in the cytoplasm of the mature megakaryocyte)

Each megakaryocyte can produce between 2000-7000 platelets.

Question 5

What type of replication do megakaryootcytes undergo?

Answer 5

Endomitosis- this is where DNA is replicated but without nuclear or cell division occuring. So the cell just gradually gets bigger and bigger

Question 6

Where are platelets discharged into?

Answer 6

bone marrow and the nucleus of the megakaryocyte is phagocytosed by macrophages.

• can take up 2-3 days.

Question 7

What shape is a platelet? and what is its normal range in the blood?

Answer 7

Discoid (0.3-0.5). Its range is 140-400 x 10^9 per L. When not needed it is resting in the blood.

Question 8

Steps involved in Primary haemostasis

Answer 8

1. Activation
2. Adhesion
3. Aggregation

this then initiated secondary haemostasis

Question 9

Why is secondary haemostasis needed?

Answer 9

primary haemostasis is not enough to stop blood loss- so a series of biochemical reaction are needed to reinforce it.

Question 10

What happens in secondary haemostasis?

Answer 10

> Soluble fibrinogen is transformed into a meshwork of insoluble fibrin

> Which then intertwines with cellular components of the forming thrombus

> Creates a supporting scaffolding