Regulation mechanisms

Long term vs short term BP control

Baroreceptor - short term adjustment

Kidney - Long term adjustment by fluid balance

 

Respiration

Inspiration
--> Increase in HR

Because

• Inspiration
  --> Lung inflation
  --> Stimulation of lung stretch receptor
  --> Increase in HR
• Inspiration
  --> Increase in venous return to atrium
  --> Stimulation of atrial stretch receptor
  --> Increase in HR
• Inspiration
  --> Vasodilation and decrease in BP

NB:

In Berne and Levy [BL8:p193]

Inflation of lung
--> Increase in vagal activity
--> Inhibition of vasomotor area
--> Vasodilation and decrease in BP

But at the same time [BL8:p93]

Moderate inflation of lung
--> Lung stretch receptor
--> Increase HR via vagus nerves

?? If vasomotor area is inhibited, why increase in HR
--> ?? Maybe it's reflex tachycardia due to drop in BP

Traube-Hering waves

Fluctuations in blood pressure synchronized with respiration

Inspiration
--> Increase in sympathetic tone
--> BP increase
* [BL8:p185]

 

Special cases

In general, stimuli that increase HR also increase BP

However, exceptions are:

1. Increase ICP

Hypertension with bradycardia (and hypoventilation)

2. Stimulation of atrial stretch receptor

Hypotension with tachycardia

3. Stimulation of peripheral chemoreceptors

Hypertension with bradycardia