Flashcards in Heritable bleeding disorders Deck (43)
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1
What is the process by which platelets AGGREGATE to the injury site?
-Damage to vascular wall
-Platelets adhere to point of injury
-Sticks to vWf (activates platelets) and then collagen
- Platelet plugs holes
- Require fibrin formation to stabilise clot
2
What intracellular processes are involved in the positive activation of more platelets?
Thromboxin release - constricts blood vessels and activates platelets
Alpha granules - coagulation factors, adhesion proteins, firbonolytics factors etc
3
What is the platelet receptor for fibrinogen?
Glycoprotein 2B3A
4
What is the platelet receptor for vWf?
Glycoprotein 1B9
5
How does aspirin mediate its function?
COX inhibitor - enzyme which synthesis thromboxin in platelet
6
What are the action of 2B3A antagonists?
Prevent platelet fibrinogen adhesion
7
What factors are activated by thrombin?
V, VIII, XI, XIII
8
What comprises the extrinsic coagulation cascade?
TF, VII
9
What comprises the extrinsic coagulation cascade?
TF, VII, X (along with factor V)
10
What comprises the intrinsic tissue cascade?
XII, XI, IX, VIII
11
What comprises the common pathway of the coagulation cascade?
X, V and prothrombin
12
What is the pathway that prothrombin time is timing?
Extrinsic/common pathway
TF substitute (fibroplatin) see how long it takes for fibrin to form)
13
What is the activated partial thromboplastin time counting?
Intrinsic pathway
foreign regents added e.g. silica based - activated factor 12
14
If prothrombin time is high, where do the deficiencies i.e.?
Factors in the extrinsic and common pathway
15
During activated partial thromboplastin timing, what is added to the mixture and why?
Calcium and phospholipids
Platelet substitute and some factors are calcium dependent
16
What effects the activated partial thromboplastin time?
Abnormalities in the INTRINSIC or common pathway
17
What 3 investigations that comprise a coagulation screen?
-Prothrombin time
-Activated partial thromboplastin time
-Thrombin clotting Time
18
What is the thrombin clotting time timing?
Time from thrombin added to plasma to formation of fibrin clot
19
What factors are involved in anticoagulation?
Protein C/S
Anti-thrombin III
Fibrinolytic system
20
What does the fibrinolytic system comprise?
Activation of plasminogen to plasmin (T-PA; tissue plasmin activation factor)
Breakdown of fibrin to fibrinogen degradation products (by plasmin)
21
How is this fibrinolytic system taken advantage of with an MI?
Use of T-PA to break down clot!
22
How are bleeding disorders characterised?
-Acquired
-Congenital
-Coagulation disorgers
-Aggregation/adhesion disorders
23
What sort of bleeding patters would you observe for secondary bleeding/coagulation defects?
Deep muscular and joint bleeds (haemarthitris)
Deep spreading haematomas
Retroperitoneal bleeding
Prolonged, recurrentbleeding
24
What sort of patterns of bleeding would you observe with primary bleeding/platelet aggregation disorders? e.g. vWf
-Mucocutaneous bleeding inc heavy periods
Petechiae/superficial bleeds
- Nose bleeds
- Immediate, prolonged bleeds, non-recurrent
25
What are the main types of defects you observe with platelet/vessel wall defects?
Reduced platelet number
Abnormal platelet function - e.g. production of thromboxane, dysfunctional receptors
Abnormal vessel wall e.g. collagen and survey
Abnormal interaction between platelet and vessel wall e.g. vW disease
26
What do all platelet/vessel or coagulation defects all end up causing?
Prolonged bleeding
27
What are the three types of vW disease?
Type I - some proteins absent but maintains multimeric structure - mild bleeding
Type 2 - right number of proteins but abnormal multimeric structure - mild bleeding
Type 3 - no vWf at all - severe bleeding
28
What are the vW disease types inheritance patterns?
Type1/2 - autosomal dominant
Type 3 - autosomal recessive
29
What is the other function for vWf?
Carrier protein for factor VIII
Therefore, reduced VIII level
Defects of coagulative disorders may present e.g. deep bleeding/haemoarthiritis
30
