Session 5- Haemostasis Flashcards
Describe the process of clotting
- blood vessel is damaged
- Initially vasoconstriction to cut of blood flow
- platelet plug formation
- Platelets activate and recruit further platelets and also activate the clotting cascade
- clotting cascade makes fibrin that forms strands and binds to platelets
Describe how a platelet plug is formed
platelets adhere to collagen on the subendothelial tissue
vWF helps in te adhesion of platelets to collagen
platelets form crosslinks to form the plug
describe the two functions of vWF
aid in adherence of platelets to collagen
carrier for F8
Name three chemicals that platelets release to activate the clotting cascade and more platelets
serotonin
thromboxane
ADP
Describe the clotting cascade
intrinsic pathway- damage to the endothelial wall
extrinsic pathway- trauma
the common point of these two pathways is Factor 10
cleaves prothrombin to thrombin
- thombin feeds back on the clotting cascade and stimulates it– Thrombin burst
Thrombin cleaves fibrinogen into fibrin
fibrin forms strands and adheres to platelets
Describe fibrinolysis.
Plasminogen–>plasmin that breaks down the fibrin mesh network
Name 3 natural anticoagulants at what these do
protein C
protein S
antithrombin
How a platelets produced?
Haematopoetic stem cells–>common myeloid progenitor cells–>megakaryocytes
off the megakaryocytes bud off platelets from the cytoplasm
approximately what is the life span of platelets
7-10days
Where are coagulation factors made?
in the liver
name three general causes of thrombocytopenia
immune destruction
non immune destruction
reduced production
name a cause of immune destruction of platelets and describe it and say the treatment used
Immune thrombocytopenia purpura
antibodies against growth proteins on platelts
treatment- Immuno suppression with corticosteroids
why would a transfusion of platelets not work with immune thrombocytopenia purpura
platelets in the transfusion would just be destroyed
Name a non immune cause of thrombocytopenia
Disseminated Intravascular Coagulation
Name four causes of decreased production of platelets
drugs and toxins
B12/folate deficiency
Virus
Cancer in the bone marrow
Name four consequences of thrombocytopenia
easy bruising
purpura
severe bleeding after trauma
intercranial haemorrhage
