Blood Clotting Pathways. Flashcards
give examples of trauma
injections surgical incision tooth extractions
what are the 3 major steps in haemostasis?
- Vascular Spasm
- Formation of Platelet Plug
- Blood coagulation (clotting)
3 reasons why must haemostasis controlled?
- To avoid inappropriate clot formation
- Clots must be eventually degraded
- clots are temporary solution
describe vacular spasms after injury?
which to products mediate this process
vasoconstriction of blood vessels after injury:
muscle cells contract which reduces blood flow to limit blood loss
opposing endothelial surfaces are pressed together and adhrere on contact
serotonin and thromboxane
name 2 vasodilator ?
prostacyclin (prostaglandin I2)
nitric oxide
Platelets are also refer to as ?
they are produced by which cell ?
what feature to platelets have?
thrombocytes
Megakaryocytes
energy generating organelles but no nuclei
what allows platelets to contract ?
highly concentrated actin and myosin
what 4 factors activate platelets?
- ADP
- collagen
- Thrombin
- Platelet activating factor (phospholipid)
what happens to platelets when they are activated?
- changing shape disc to sphere with pseudopodia
- allowing it to aggregate and coagulant activity
- granules compounds involved in haemostasis=
- ADP/ Serotonin/ fibronectin and von willebrand factor (vWF)
- aggregate
- adhere to vessel wall
- synthesis thrombane
how is a platelet plug formed after activation?
Adhesion to the vessel wall at the site of injury
Platelets aggregate and build up on an occulsive platelet mass forming a PRIMARY HAEMOSTATIC PLUG
This can be washed away by blood flow when vasoconstriction decreases.
It is stablised by fibrin
where is von Willebrand Factor produced from ?
platelets and endothelial cells
what are the 2 platelet and platelet related bleeding disorders?
- von Willebran disease- autosomal disease affecting vWF
- less common disease that affects the receptors found in platelet membrane- involved in adhesion and aggregation.
anti platelelet drugs are used to treat …
through…
such drugs include
arterial thrombosis- blood clotting in the vessel
through decreasing platelet aggregation and inhibit thrombus formation
Asprin/ Platelet receptor antagnosists /Platelet ADP receptor antagonists.
what is the role of collagen
structure and function of small blood vessels
what is aquired and cogenital disease
cogenital is something u were born with and aquired it something u develop after birth.
name 1 cogenital disease for excessive bleeding
name 2 aquired disorders for excessive bleeding
both are linked to collagen
1) Ehlers Dnalos syndrome
- Vitamin C deficiency
- excessive glucacorticoides (steroid hormones)
what do blood coagulation factors form when they interact in
- small vessels
- and arteries and viens
- secondary fibrin rich haemostatic plug
- secondary thrombus
intrinsic pathways are activated by?
exposure of flowing blood to sub endothelial collagen exposed by vessel damage
extrinsic pathway are activated by
tissue damage which exposes flowing blood to proteins called tissue factors
what is the feature of the final common pathway
fibrinogen is converted to fibrin
how is a fibrin clot formed ?
through the intertaction between intrinsic/ extrinsic and final common pathways
what is the role of a clot on top of a platelet plug?
strenghtens the plug and reinforces the seal
fibrin:
- features
- role
- arises ?
- insoluble, thread like molecule
- forms a loose meash that traps blood cells
- genertated by fibrinogen which is a soluble plasma protein synthesised by liver
what are the 2 roles of thrombin ?
- catalyses conversion of fibrongen to fibrin
- activates factor XIII
