5 Flashcards
Define haemostasis
Bodys response to stop bleeding and blood loss
What are the 3 factors of haemostasis?
- Blood vessels
- Platelets
- Coagulation
What is the role of blood vessels in haemostasis?
Constrict to reduce blood loss
What is the role of platelets in haemostasis?
Adhere to damaged vessels and each other
Form platelet plug
Draw out the clotting cascade
Instrinsic 11 - 9 - 10 Extrinsic 3 - 7 -10 Prothrombin - (10) - Thrombin Fibrinogen - (Thrombin) - Fibrin 8 - (Thrombin) - 8 activated --> cross link fibrin
Which factors is thrombin a +ve feedback for?
5, 8, 11
What are 4 thrombin inhibitors?
- Antithrombin III
- Apha1-antitrypsin
- Alpha2-macroglobin
- Protein C/S
What is fibrinolysis?
Fibrin breakdown by plasmin
How is plasmin formed?
Plasminogen - (Streptokinase) - Plasmin
What is thrombosis?
Formation of a solid mass of blood within circ system
What is Virchows Triad?
Factors that contribute to thrombosis
Name the 3 factors in Virchows Triad
- Change in blood flow (turbulence)
- Change in blood components
- Change in vessel wall (atheroma)
What are the effects of thrombosis on arteries?
- Ischaemia
2. Infarction
What are the effects of thrombosis on veins?
- Ischaemia
- Infarction
- Congestion
- Oedema
What are the 5 outcomes of thrombosis?
- Lysis (thrombus broken down by fibrinolytic system, blood flow reestablished)
- Propagation (thrombus spreads)
- Organisation (Repair process w. fibroblasts n cap)
- Recanalisation (blood flow reestablished)
- Embolism
What is an embolism?
Blockage of blood vessel by solid/liquid/gas @ site distant from origin
What are the 4 regions of thromboembolisms?
- From systemic veins –> gets stuck in lung vessels
- From atheromatous carotid art –> brain (stroke)
- From atheromatous abd aorta –> leg arteries
- DVT
What are the causes of DVT?
Pregnant women chugging OC abt to board a plane
What are the treatments for DVT?
- IV Heparin (anticoag) (cofactor for antithrombin III)
2. Oral Warfarin (slow) (x vit K dependent clotting factor synth)
What is a Massive Pulm Embolism?
60% reduce in blood flow
Rapidly fatal
What is a Major Pulm Embolism?
Medium sized vessels blocked
SOB / cough / bloody sputum
What is a Minor Pulm Embolism?
Small peripheral pulm arteries blocked
What can recurrent Pulm Embolisms cause?
Pulm hypertension
What is DIC?
Disseminated IV Coag
Inapprop activation of clotting cascade –> uses up clotting factors
When you acc need clotting factors you dont have so you bleed
What triggers DIC?
Infection
Trauma
Liver disease
Obstetric complication
What is the inheritance pattern for haemophilia?
X linked (more in boys) Nonsense mutation
What is Type A Haemophilia?
Factor 8 Defic
What is Type B Haemophilia?
Factor 4 Defic
What is haemophilia?
Inability to clot, so you bleed out or into joints / brain
What happens if a muscle bleed in haemophilia?
Nerve necrosis
What is the treatment for haemophilia?
Factor replacement therpy
What is the name for low platelet count?
Thrombocytopenia
What are the 3 causes of thrombocytopenia?
- Platelet prod failure
- Platelet destruction
- Platelet sequestering (removal)
What can accompany thrombocytopenia?
Bone marrow malfunctions e.g leukaemia
What is thrombophilia?
Hypercoag –> increased risk of thrombosis
