Haemorrhage Flashcards
what 3 things happen when a blood vessel is damaged to help prevent excessive blood loss?
vascular spasm
platelet plug formation
coagulation
what is vascular spasm?
immediate but temporary constriction of blood vessel resulting from contraction of smooth muscle within the wall of the vessel. this can close small vessels completely and stop the flow of blood through them.
what causes the vascular spasms?
nervous system reflexes and chemicals that are released
what is a platelet plug?
it is an accumulation of platelets that can seal up small breaks in a blood vessel.
why is platelet plus formation important
it is important in maintaining the integrity of the circulatory system of the circulatory system because small tears occur in the smaller vessels and capillaries many times a day, and platelet plus formation quickly causes them to close
what are the steps of platelet plug formation
platelet adhesion
platelet release reaction
platelet aggregation
activated platelets express phospholipids and clotting factor V
what happens when platelet plugs and vascular spasms are not sufficient
coagulation, or blood clotting occurs, resulting in the formation of a clot. all clotting factors must be activated to start the coagulation cascade.
what are 5 types of shock
hypovolaemic distributive obstructive cardiogenic sceptic
what causes hypovolaemic shock
caused by blood loss
what causes distributive shock
a) powerful emotion can cause excessive vasodilatation
b) antigen/anaphylactic shock e.g. bee sting or bacterial toxins
histamine release makes blood vessels leakier and causes vasodilatation
what causes obstructive shock
restricted venous return
what causes cariogenic shock
Heart unable to pump during a heart attack
Transfusion of salt and fluid is required to replace fluid losses due to haemorrhage
what are symptoms of shock
1) Rapid ‘thready’ pulse- increase in heart rate but not the bounding pulse of exercise
2) Cool clammy skin- increase in peripheral resistance applies to the cutaneous capillary beds and hence
the skin will seem cool and clammy since exocrine secretion continues
3) Low blood pressure- Loss of blood volume leads to lower blood pressure if the loss is moderate to severe. Over times the blood pressure can rise but may fall again.
4) Low urine output- Endocrine factors cause renal retention of salt and fluid
what is shock
shock can be defined as a state of impaired tissue oxygenation resulting in tissue oxygen debt
how does the body compensate for shock
the body tries to compensate for the decrease in oxygen through metabolic, biochemical, and physiological responses, e.g.
- anaerobic respiration which breaks down glucose to produce ATP for energy (lactate is a by product)
- the body will ensure vital organs have enough oxygen first e..g brain, lungs, heart
