Physiological Adjustment of V/Q Ratio (PK5)

Question 1

2 mechanisms to alter V/Q ratio

Answer 1

• Alter bronchiole tone (alter V)
• Alter arteriole tone (alter Q)

Question 2

How is blood diverted away from a hypoxic area of the lung, and what does this show when comparing ventilation and perfusion?

Answer 2

• Vasoconstriction
• Areas of low ventilation have low perfusion too

Question 3

How does hypoxic pulmonary vasoconstriction (HPV) occur?

Answer 3

• Hypoxia inhibits K+ channels
• Membrane depolarised
• Ca2+ moves through voltage-gated Ca2+ channels
• Pulmonary artery smooth muscle contracts