L.48. Haemorrhage & Shock Flashcards
What does decreased blood volume lead to?
What does this result it?
Decreased blood volume
- > decreased blood pressure
- > shock
Describe how a healing “aggregate” is formed.
Platelets form an aggregate by adhering to a lesion and clumping together. Positive feedback causes further aggregation.
Where are many clotting factors made?
Kidneys
Which vitamin do many clotting factors require?
Vitamin K
Give an example of a clotting factor, and what it is broken down to.
Fibrinogen -> Fibrin.
Which enzyme is required for fibrinolysis?
Plasmin
What is fibrinolysis?
Fibrinolysis is the process of dissolving a clot which has served its purpose.
Arterial baroreceptors try to restore blood pressure. What is this process mediated by and which hormones does it involve?
Mediated by : sympathetic nerves
Involves hormones : adrenaline
angiotensin
ADH
Give an exampleof a medium term response to blood loss
Decreased fluid loss via kidneys
What does the mechanism of “Starling’s Forces” ensure?
A constant balance between filtration and reabsorption to maintain hydrostatic and oncotic pressure.
What is hydrostatic pressure?
Blood pressure
What is oncotic pressure?
Plasma protein induced pressure
Due to baroreceptor reflexes, decreased blood pressure causes _______________ of arterioles.
Vasoconstriction
During haemorrhage, what do “Starling’s forces” ensure?
Reabsorption is greater than filtration.
Renin-angiotensin-aldosterone and ADH are both examples of what?
Vasoconstrictors.
With decreased fluid loss in the kidney, what happens to the glomerular filtration rate?
Decreased glomerular filtration rate
When glomerular filtration decreases, there is increased reabsorption of Na+ and H20 by stimulating the release of ____________ and _____________ [hormones}
Renin-angiotensin-aldosterone
ADH
Plasma volume decrease
->
Baroreceptor distension _________ (Increase/decrease)
->
_____________ (Increased/decreased) ADH release
Plasma volume decrease -> Baroreceptor distension decrease -> Increased ADH release
Which part of the body controls thirst?
Hypothalamus
Give an example of a change in the body which stimulates thirst.
Increased plasma osmolarity stimulates thirst.
What action can help replace red blood cells?
Drinking water
What is erythropoiesis?
The process of creating mature red blood cells from stem cells.
What causes shock?
Inadequate blood flow to a tissue
What is a common cause of shock?
Lack of blood
Name the 2 forms of shock.
Reversible
Irreversible (fatal)
Name 3 types of shock which can occur.
- Hypovolaemic
- Low resistance
- Cardiogenic
Describe the causes of a hypovolaemic shock.
Decreased ECF from haemorrhage, sweating, diarrhoea etc
Describe the causes of a low resistance shock.
Widespread vasodilation, eg anaphylactic shock
Describe the cause of a cardiogenic shock.
The heart fails as a pump.
