Ventillation & Perfusion Relationships

Question 1

The alveolar gas equation is used to know/calculate what the inspired O₂ needs to be produced a desire P_AO₂. First, what equation do we use to determine P_AO₂?

Answer 1

P_AO₂= P_IO₂ - (P_aCO₂/R)

= [(Barometric Pressure- water vapor pressure)x(F_IO₂)] - (P_aO₂/0.8)

= [(760@sea level- 47usually) * 21%usually] - (P_aO₂/0.8)

Question 2

What equation do we use to determine the Alveolar- arterial gradient?

Answer 2

P_AO₂ - P_aO₂

Question 3

At which of the following locations of the lung would the alveolar be largest at rest and only get a little bigger during inspiration?

A. Apex of the lung

B. Middle of the lung

C. Base of the lung

Answer 3

Apex of the lung

Question 4

What is the average ventillation and perfusion ratio?

Answer 4

0.8

4/5

Question 5

Which of the following eventually causes a an essential R to L shunt?

A. early low V/Q

B. prolonged high V/Q

C. prolonged low V/Q

D. early high V/Q

Answer 5

prolonged low V/Q

Question 6

Early on with a low V/Q ratio what happens to O2 and CO2 levels in the alveoli?

Answer 6

O2 decreases

CO2 increases

Question 7

What do we see happen to the O2 and CO2 levels when the V/Q ratio is high?

Answer 7

O2 increases

CO2 decreases

Question 8

Eventually what values equilibrate under low V/Q conditions?

A. Concentration of O2 with CO2

B. Venous blood and alveoli

C. Alveoli and atmospheric conditions

D. None of the above

Answer 8

B. Venous blood and alveoli

Question 9

Eventually what values equilibrate under high V/Q conditions?

A. Concentration of O2 with CO2

B. Venous blood and alveoli

C. Alveoli and atmospheric conditions

D. None of the above

Answer 9

Alveoli and atmospheric conditions

Question 10

What is the relative V/Q ratio at the apex, middle, and base of the lung?

Answer 10

Apex: high

Middle: normal

Base: low