Circulatory Shock

Question 1

what is circulatory shock

Answer 1

profound circulatory failure causing poor perfusion of vital organs

ie. low blood pressure and its physiological consequences

Question 2

3 major types of circulatory shock

Answer 2

Hypovolaemic

septic

cardiogenic

Question 3

mechanism which try to maintain blood pressure in shock

Answer 3

carotid body and sinus on right side - bifurcation (splitting) of artery into internal & external

2 carotid bodies and 2 carotid sinuses on either side of the neck - consists of groups of cells which sense the partial pressure of oxygen = carotid bodies

if blood pressure drops - carotid sinuses ‘sense’ this
respond by nerve signals to the brain stem
brain stem tells the heart to pump harder and faster, via nerve signals =faster pulse rate

Question 4

Normal Blood Pressure

Answer 4

normally = 120/80
venous pressure is much lower
120 = when blood comes past, 80 = resting pressure

normal blood pressure relies on:
1- enough blood
2- smooth muscle in vessels having a certain ‘tone’
3- heart pumping blood

Question 5

Hypovolaemic shock process

Answer 5

Rib penetrates spleen and causes major haemorrhage

systemic (arterial) blood pressure normal for a certain period of time then, as blood flows out of damaged spleen less blood is present in other vessels, vessel collapses as have no more blood in them

less blood in vena cava which also collapses, then venous pressure falls virtually to 0

now almost no blood enters right side of heart, very little blood in lungs, very little blood goes to brain and rest of body

carotid sinuses up-regulate the sympathetic nervous system

Question 6

complications of shock

Answer 6

decreased perfusion (ischaemia) of brain - initially reversible but then becomes permanent (infarct)

decreased perfusion of kidneys - initially reversible, then more severe (ischaemic necroses of renal tubules)