Respiratory Physiology 2

Question 1

Explain the relationship between pulmonary artery pressure and pulmonary blood resistance

Answer 1

Pulmonary artery
low pressure
Low resistance (much less resistance than systemic blood flow)

Question 2

Describe the effects of distension and recruitment on pulmonary blood pressure

Answer 2

Hydrostatic pressure of the blood in the vessels is affected.

Question 3

Describe the effect of gravity on pulmonary blood flow

Answer 3

Lower regions of vessels are affected by gravity more, so the blood vessels are more distended, thus there is less resistance.

Thus three zones are used to describe the variation
Z1 = no gas exchange at rest ( as the pressure of the vessel doesn’t get higher than the alveolar pressure)

Z2 = intermittent at rest, flows during systole, not diastole.

Z3 = flow through the whole cardiac cycle, as

Ventilation-perfusion mismatch
- too much blood flow for the air in the alveolar

Question 4

Explain the effects of exercise on pulmonary blood flow

Answer 4

The top region has the greatest difference in the increase of blood flow. While bottom may increase in blood flow less.

Overall more capillaries are diffused and increase dilation of though already diffused

3 ways that lungs accommodate for the increased blood flow
Increase in no. of open capillaries (3x)
Distension of all capillaries (2x)
Increase pulmonary pressure increase
- this end up reducing resistance poiseuille law (bigger diameter = less resistance)

Question 5

Describe the effect of hypoxia on pulmonary blood flow

Answer 5

Alveolar with lower than 70% oxygen = vasoconstriction
This allows the blood to be distributed to where it is most needed.
Sending blood to the alveolar with higher O2 saturation.