haemostasis and inherited blood disorders Flashcards
what do glycoprotein molecules have receptors for?
agonists, adhesive proteins, coagulation factors, other platelets
what are the most abundant receptors on the platelet cell membrane?
Gp2b/3a heterodimer complex, Gp1b
what what platelet specific granules are in a platelet?
o Dense osmophilic granules; dense bodies, alpha granules
o Nucleotides; ADP
o Alpha granules
what do alpha granules contain?
VWF, platelet factor 4, b-thromboglobulin, thrombospondin, factor V, fibrinogen, fibronectin, platelet derived growth factor, high molecular weight kininogen, tissue plasminogen activator inhibitor-1
what is Bernard Soulier syndrome?
Lack of Gp2b
what is Glanzmann’s syndrome?
lack of Gp2b/3a
how are serious inherited platelet disorders treated?
Likely to need platelets or Novoseven
name less serious platelet disorders
o Storage pool disorders
o Weak agonist response defects
what is the inheritance pattern of von willebrand disease?
autosomal inheritance
what is type 1 VWD?
mild to moderate deficiency; VWF is working but there isn’t enough of it
what is type 2 VWD?
protein is present but isn’t working
what is type 3 VWD?
totally absent protein
how do you treat VWD?
DDAVP, tranexamic acid, VWF containing concentrate
how does DDAVP work?
stimulates a person to release more VWF that’s already stored in platelets
what treatment is given is someone with VWD experiences prophylaxis at home?
they can be taught to treat themselves intravenously
where is tissue factor found?
Present on subendothelial tissue – expressed by cells which are normally not exposed to flowing blood
what does APTT test?
the intrinsic pathway
what does PT test?
the extrinsic pathway
what does thrombin time test?
the common pathway
in severe haemophilia, where do you experience bleeding?
soft tissue, joints (knees, ankles, elbows), psoas, intracranial, operative sites (haematomas may become compromising)
what is antithrombin?
- Major inhibitor of thrombin and Xa - also inhibits VII, IX, XI
- Member of the SERine Protease INhibitor family
how does heparin affect antithrombin?
Inhibitory activity increased 5 -10,000 fold in the presence of heparin
