haemostasis, haemorrhage and shock Flashcards
what is haemorrhage?
an acute loss of blood from a damaged blood vessel
what is shock?
the state in which the decreased blood volume results in a fall in blood pressure and impaired delivery of nutrients to cells
what should the immediate action to blood loss be?
stop the bleeding
what should the short term action to blood loss be?
restore the blood pressure
what should the medium term action to blood loss be?
restore fluid volume
what should the long term action to blood loss be?
replace blood consitiuents
what is haemostasis?
stopping blood loss
what are the components involved in haemostasis?
- vascular response
- platelet response
- plasma response
what is coagulation?
plasma response
describe the vascular response in haemostasis?
Smooth muscle
- Spasm due to trauma
- Myogenic response
- Humoral factors (vasoconstrictors)
Endothelium
- Platelet adhesion and aggregation
- Anticlotting and fibrinolysis
describe the platelet response in haemostasis?
- Damage to blood vessel causes turbulent blood flow so platelets come into contact with vessel wall (collagen)
- Platelets adhere; clump together (aggregate)
- Release chemicals that cause further aggregation (Positive feedback)
- Formation of platelet plug
- Effective in sealing small blood vessels
describe the formation of a platelet plug
- damaged blood vessel
- platelets aggregate and release chemicals
- thromboxane A2 and ADP
- vasoconstriction
- platelet plug
describe coagulation in haemostasis?
- Various plasma proteins and tissue components combine to convert fibrinogen to fibrin to form the blood clot
- Numerous ‘clotting factors’ are involved (many made in the liver)
- The synthesis of several clotting factors requires the presence of vitamin K
- The clotting factors are activated in an enzyme cascade
- One activated factor activates the next one in the sequence
where are many of the clotting factors involved in coagulation made?
the liver
what is required for the synthesis of many clotting factors?
vitamin K
what can have an affect on coagulation?
calcium deficiency
which blood clotting factor doesnt exist?
VI (same as IV)