H4 Flashcards
1
Q
Define thrombopoesis
A
The formation of platelets in bone marrow
2
Q
What are platelets?
A
- small, anucleate cells
- from cytoplasm of megakaryotes (large bone marrow cell)
- destroyed in spleen (phagocytosis) or in liver (Kuppfer cells)
3
Q
What is the lifespan of platelets?
A
7-10 days
4
Q
Describe the role of thrombopoetin (TPO) in thrombopoiesis
A
- primary regulator of thrombopoesis
- unbound TPO stimulates platelet production
- decreased TPO -> increased platelet count
5
Q
Describe the production of platelets
A
- Platelets produces from megakaryotes (large bone marrow cells)
- TPO binds to receptor: causes a cascade, which causes profileration, and megakaryotes increase in size
- Once megakaryotes develop into giant cells they undergo fragmentation and release over 1000 platelets per megakaryote.
6
Q
What are causes of thrombocytopenia?
A
- Decreased platelet production
- Increased platelet consumption
- Abnormal platelet distribution
- Pseudothrombocytopenia: Platelet clumping
7
Q
What are causes of thrombocytosis?
A
- Primary : acquired or inherited
- Secondary : reactive-haemorrhage , trauma, iron deficiency, anaemia, infections, inflammation
- Tertiary: splenectomy and hyposplenism
8
Q
What is thrombocytopenia?
A
low blood platelet count
9
Q
What is thrombocytosis?
A
excessive number of platelets in the blood
