5.4.2 Circulatory Disturbances 2 Flashcards
What is haemostasis?
Localised interaction between endothelium, platelets, coagulation factors, to cease bloodloss
What are the five stages of haemostasis?
1 - Transient vasoconstriction
2 - Primary haemostasis: platelet aggregation and platelet plug
3 - Secondary haemostasis: fibrin platelet aggregation
4 - Concurrent thrombosis/fibrinolysis
5 - Tissue repair
What is a haemorrhage? What are the two types?
Extravasation of erythrocytes into the extravascular space.
Rhexis - vessel wall disruption
Diapedesis - blood vessel wall allows BRCs to escape
What causes a decrease in platelets (thrombocytopenia)?
↓ production
↑ destruction
↑ use
What are the 7 causes of haemorrhage (diapedesis)?
1 - endothelial injury
2 - Immune Mediates Disease
3 - Developmental collagen disorders
4 - Collagen defects in guinea pigs and primates deficient in Vit C
5 - Thrombocytopaenia
6 - Thrombocytopathy
7 - Reduced conc. of coagulation factors
What may cause Thrombocytopathy?
Inability to adhere/aggregate to injury site
Inherited defects
Von Willebrand’s disease
What causes a decrease in conc or function of coagulation factors (CFs)?
Inherited deficiencies of Cfs
↓ production
↓ production of Vit K dependant CFs
↑ use of CFs
What is Petchaie?
Pin point 1-2mm hemorrhages in the skin, mucous membrane, serosal surfaces
What is Petchaie?
Pinpoint 1-2mm hemorrhages in the skin, mucous membrane, serosal surfaces
What is Eccymoses?
Larger (2-3cm) hemorrhages with more extensive damage
What is Suffusive haemorrhage?
Large continuous areas of haemorrhage
What is a thrombosis?
Formation of excessive/inappropriate clot on endothelium of blood/lymphatic vessel or in heart
What is an embolus?
Particulate matter travels within the vascular system. Can lodge and cause obstruction of small vessels > infarction (tissue death)
What is a thromboemboli?
Emboli derived from fragments of a thrombosis.
What is infarction?
Area of peracute ischemia that undergoes coagulative necrosis (following occlusion of blood vessels)
What can cause abnormal blood flow?
- Local stasis or ↓ blood flow
- Cardiac disease
- Aneurysm
- Hypovolaemia
What does abnormal blood flow cause?
- Endothelial injury / dysfunction
- Allows platelet to more readily interact with endothelium
- Prevent dilution of activated clotting factors by fresh flowing blood + inflow of inhibitors
- Turbulence allows interaction between coagulation factors
What causes hypercoagulability?
- Inflammation
- ↑ platelet activity
- ↑ clotting factor activation
- Anti-thrombin III deficiency
Describe the appearance of an arterial thrombi
- Initiated by endothelial damage
- Red/grey/ pale
- firmly attached
- Lamintaed
- Tails extending downstream
Describe the appearance of a venous thrombi
- Often areas of stasis
- Dark red, gelatinous, soft
- Occlusive, moulded to vessel wall
- Extend upstream
- loose attachement
Describe the fate of a thrombus (5)
Dissolution
Propagation
Organisation
Recanalisation
Embolisation
