Disturbances in blood pressure and volume

Question 1

What is the skeletal muscle pump?

Answer 1

Tonic contraction for posture
Limits venous pooling
Rhythmic contraction of toes and calves etc also effective
Venous valves

Question 2

What is the respiratory pump?

Answer 2

Deeper breathing when standing promotes venous return and limits venous pooling

Question 3

What do both pumps aid?

Answer 3

Increase in CVP
- increase in EDV, SV, CO and ABP
Prevent oedema

Question 4

What does hypertension increase the risk of?

Answer 4

Heart failure
Stroke
Congestive heart failure

Question 5

What is congestive heart failure?

Answer 5

Arises from:
myocardial infarction
chronic hypertension
Systolic contraction of ventricular muscle is weak
Ejection fraction is low
Ventricles, atria and venous vessels are over filled/distended
Large EDV but low SV
CO and ABP are low

Question 6

What is the baroreceptor response in someone with congestive heart failure?

Answer 6

Increased sympathetic activity
Decreased parasympathetic activity
Ventricular contractility increases with little effect
Retention of water by kidney

Question 7

How can we test baroreceptor reflexes?

Answer 7

IV injection of vasoconstrictor causes baroreflex bradycardia
IV injection of vasodilator causes baroreflex tachycardia

Question 8

How can we test cardiac and vascular components of the baroreceptor reflex?

Answer 8

Cannulate the carotid artery
Change sinus pressure and record afferent nerve activity
In humans, neck cuff mimics changes in ABP

Question 9

What changes occur in hypertension?

Answer 9

Set point of the baroreceptor reflex changes

Output of symapthetic nerve activity from CNS is chronically raised

Question 10

What changes occur in congestive heart failure?

Answer 10

Set point of baroreceptor reflex is not changed
Baroreflex sensitivity is reduced
Volume receptor reflex also reduced