Gas Transport in the Airways

Question 1

Common causes of hyperventilation include ____, ____, or _____.

Answer 1

• acute hypoxemia (low arterial oxygen)
• metabolic acidosis
• CNS stimulation

Question 2

The exact relationship between O2 consumed and CO2 produced is given by _______, which is the ratio of the amount of CO2 generated (VCO2 ) per amount of O2 consumed (VO2).

Answer 2

the respiratory exchange ratio (R)

Question 3

LO 3. Calculate alveolar PAO2 given known values of PACO2, barometric pressure, and respiratory exchange ratio.

Answer 3

PAO2 = PIO2 – (PACO/R) + k

Question 4

Hypoventilation can be caused by _____, _____, or ______.

Answer 4

• obstructive/restrictive disease
• metabolic alkalosis
• CNS depression

Question 5

What would happen if alveolar ventilation (VA) went down?

Answer 5

PACO2 will increase, leading to CO2 accumulation

Question 6

What is the composition of dry air?

Answer 6

• O2 21%
• CO2 0%
• N2 79%

Question 7

The exact relationship between O2 consumed and CO2 produced is given by the respiratory exchange ratio (R), which is _______.

Answer 7

the ratio of the amount of CO2 generated (VCO2 ) per amount of O2 consumed (VO2)

Question 8

What does R equal for most diets?

Answer 8

0.8

Question 9

LO 2. Define the respiratory exchange ratio and describe why values can vary.

Answer 9

• The exact relationship between O2 consumed and CO2 produced is given by the respiratory exchange ratio (R), which is the ratio of the amount of CO2 generated (VCO2) per amount of O2 consumed (VO2):
• R = VCO2/VO2
• Where R is different metabolites, usually 0.8

Question 10

LO 1. Calculate the partial pressure of oxygen in inspired air PIO2.

Answer 10

PIO2 = (PB – 47 Torr) × 0.21 (760 torr at sea level, 620 in Denver)