T2 L2: Haemostasis Flashcards
(77 cards)
What is extravasation?
Movement of fluid and molecules out of vessels
What is the first stage of wound healing?
Haemostasis
What does the endothelium secrete when it’s injured?
It stops secreting inhibitors and starts secreting von Willebrand factor
What does von Willebrand factor (vWF) do?
A multi-subunit protein that serves both to anchor the platelets to the subendothelial collagen and as a carrier protein for Factor VIII in plasma
What is the 3 step platelet-based pathways for repair of blood vessels?
- Platelets form a haemostatic plug by adhesion, activation and aggregation.
- Coagulation using the enzyme cascade
- Vasoconstriction by release of vasoconstrictors and pro-thrombotic agents `
Give 3 examples of molecules used for vasoconstriction
Serotonin, ADP, and Thomboxane A2
What are the 3 points of Virchow’s triad?
Venous stasis, activation of blood coagulation, and vein damage.
What white blood cells develop from the common lymphoid progenitor?
NK cells, T-cells, and B-cells
What do plasma cells develop from?
B-cells
What common progenitor do megakaryocytes develop from?
The common myeloid progenitor
What cell do thrombocytes develop from?
A megakaryocyte
What is thrombocytopaenia?
Low platelet count
How many platelets can 1 megakaryocyte produce?
About 4000
What does exocytose mean?
Excrete
What 3 changes occur to platelets once they’re activated?
They start to exocytose, they change shape and their respiratory rate increases
Describe the shape of an activated platelet
Irregular shape with many protruding pseudopodia
What do platelets adhere to during the first step of activation?
To exposed collagen
What do platelets exocytose once they’re activated?
Dense granules like serotonin, ADP, calcium, and Thromboxane A2 (TXA2)
What molecule stimulates platelet aggregation?
ADP
Which drug blocks platelet aggregation?
Prasugrel via fibrinogen
What happens during platelet activation in detail?
Extracellular ADP activates P2Y12 receptors and cause a cation flow
Which 2 clotting factors are not enzymes?
Factor V and factor VIII (they’re co-factors)
Where are tissue factors in terms of the endothelium?
Behind the endothelium, it’s revealed when the endothelium is damaged which causes coagulation
Where are clotting factor precursors found?
In the blood