Quiz 1 Flashcards
What are the five stages of hemostasis?
- Vasoconstriction
- Formation of platelet plug
- Activation of clotting cascade
- Formation of Fibrin clot
- Clot Retraction and dissolution
What does the coagulation system do?
Forms a clot at an injured or inflamed site.
Also,
Prevents infection, stops bleeding, and provides framework for repair and healing.
What is the coagulation system composed of?
A platelet plug and crossed think mesh of protein called fibrin
When there is no side of injury what happends in the vessel?
The inside of the vessel activily repells clotting.
Actively anti-clotting
What do platelets look like?
What is there function?
How are they formed?
- Disk Shaped cytoplasmic fragements-no nucleus
- Essential for coagulation and control bleeding
- Formed by fragmentation of megkaryocyte precursors
Megkaryokyte to—–>?
Platelet
What is hematopoiesis?
Is the process of blood cell formation
Occurs in the bone marrow after birth
What are the 2 stages in hematopoietic development?
Proliferation of precursor cells
Differentiation of precursor cells
Talk through the development of Platelets
What is this process called?
First starting for a megakaryocyte, the cell undergoes the nuclear phase of cell division,
But does not undergo cytoplamic division
The megakaryocyte expands due to DNA doubling, then they are broken into fragments.
Endomitosis
Platelets or thromombocytes are what?
membran bound fragments of megakaryocyte cytoplasm
Production and differentiation of megakaryocytes are regulated by Thrombopoietic growths factors:?
Thrombopoietin
Interleukin-11
Platelets are destroyed in the?
Spleen
True or False
Platelet function and count corelates to their function?
False
What is a normal Platelet count?
140,000- 340,000/mm3
ThromboCYTHEMIA count
greater than 600,000/mm3
Thrombocytopenia count
less than 100,000
Immune thrombocytopenic purpura (ITP) what occurs and how is it mediated?
Antibody mediated distruction of platelets
How is ITP treated?
glucocorticosteriods
Thrombopoietin receptor agonists
Hemostasis has 3 parts
Activation of platelets (primary)
Activation of coagulation factors (secondary)
Activation of the fibrinolytic system
In what step is the fibrin clot and activation of clotting cascade?
2 secondary hemostasis
Activation of coagulation factor
In hemostasis I, what occurs? What is it also called?
It is called primary hemostasis
Vasoconstriction and formation of a platelet plug
In an uninjured blood vessel what stops the clotting and platelet activation?
Antiplatelet activities release mediators which inhibit the activation of platelets
Antithrombic activities inhibit the clotting cascade
Fibrinolytic activities breakdown clots
What does dipyridamole do?
increases the cellular concentration of cAMP/cGMP
This prevents platelet activation
Aspirin blocks what?
COX 1 its a really good inhibitor
Causing degranulation
Clopidogrel blocks?
P2y12
Causing degranulation
Platelets activation by the clotting cascade is activated by?
Thrombin
What is thrombin formed by and what does it do?
What does it lead to?
Formed by coagulation cascade and it binds to Protease Activated Platelet receptors PAR1 and PAR2
Aggregation and activation of platelets
Four factors secreted by platelets? During platelet degranulation
- ADP activates P2Y1 and P2Y12, this promotes platelet aggregation and secretion
- Thromboxane A2 (TXA) made via COX1 promotes platelet aggregation and vasoconstriction
- Serotonin(5-HT) promotes vasoconstriction
- PDGF (platelet-derived growth factor)
- Chemotactic, mitogenic
- Stimulated wound healing
Platelet plugs dont form without what?
What drugs block this?
Fibrinogen
Abciximab, eptifibatide, tirofiban
What complex is extremely important for platelet aggregation?
The GPIIb-IIIa fibrinogen complex
This is a dope ass drug target
Platelets do what to increase efficacy?
Change shape to increase surface area
