Circulation 3

Question 1

What is circulatory shock

Answer 1

Circulatory failure causes poor perfusion of vital organs

In practice, shock = Low blood pressure and its physiological consequences

Question 2

What are the main causes of shock

Answer 2

1. Hypovolaemic
2. Septic
3. Cardiogenic
4. Other

Question 3

What does normal BP require

Answer 3

Enough blood in system (5 litres in adult)
Smooth muscle in vessels having certain ‘tone’
Heart pumping blood

(tone=amount of tension in muscle)

Question 4

Explain the physiological mechanisms which try to maintain blood pressure in shock

Answer 4

-2 carotid bodies and 2 sinuses on either side of neck
-Consist of groups of cells which sense partial pressure of oxygen
-Cartoid bodies ‘sense’ BP change, send signal to brainstem, signals heart to pump harder/faster

-Physiological response to low blood pressure = faster pulse (heart rate)
-Adrenaline causes heart to pump harder/faster

Question 5

What is another way in which BP is maintained

Answer 5

Increased vascular tone in vessels in limbs and abdomen, blood pushed up to chest and head
Keeps vital organs alive

Question 6

Describe Hypovolaemic shock

Answer 6

Low bp - severe reduction in amount of blood in circulation
High pulse - physiological response to low bp

Question 7

Describe cardiogenic shock

Answer 7

heart unable to pump sufficent blood to brain and vital organs

Question 8

Describe septic shock

Answer 8

Bacterial infection affects BP

Cardiac muscle looses it’s tone – slow HR = bradycardia

Question 9

What is vascular tone

Answer 9

contractile activity of vascular smooth muscle cells in walls of small arteries and arterioles

Question 10

Describe the complications of shock

Answer 10

Brain injury (ischaemic infarction of brain tissue)
Decreased perfusion of kidneys, initially reversible, then more severe (ischaemic necrosis of renal tubules)