Short Term Control of Blood Pressure

Question 1

Describe the components of arterial baroreceptor reflex

Answer 1

Stretch-sensitive mechanoreceptors (baroreceptors) are located in the walls of the;

• Carotid arteries: supplied by glossopharyngeal nerve
• Aorta: supplied by vagus nerve

Question 2

Describe the function of arterial baroreceptor reflex

Answer 2

Sympathetic;
- Vasodilation
- Decrease in force of contraction (+ parasympathetic)
- Decrease in HR 
Cause decrease in TPR, CO and thus, BP.

Question 3

Identify other inputs to the medullary cardiovascular centres

Answer 3

• Cardiopulmonary baroreceptors (more so in long term control of BP)
• Central chemoreceptors
• Chemoreceptors in muscle
• Joint receptors
• Higher centres

Question 4

Explain the relationship between CO, TPR and MAP

Answer 4

MAP = CO x TPR

Question 5

Describe the effect of changes in posture on the CVS

Answer 5

Standing;

• Increased hydrostatic pressure causes blood to pool in veins/venules of lower limbs
• Decrease in VR, EDV, preload, SV, CO, MAP
• Decrease in baroreceptor firing rate

Question 6

Describe the effect of the Valsalva manoeuvre on the CVS

Answer 6

• Increase in thoracic pressure is transmitted into aorta
• Decrease in VR, EDV, SV, CO, MAP
• Decrease in MAP detected by baroreceptors, which initiate reflex to increase CO and TPR
• Decrease in thoracic pressure is transmitted into aorta
• VR returns to normal so SV increases but this takes time

Question 7

Define carotid sinus

Answer 7

The reflex area of the carotid artery.