Ventilation Flashcards
What is the difference between the two types of ventilation?
Pulmonary - the total air movement into or out of the lungs.
Alveolar - fresh air getting to alveoli for gas exchange.
Describe the movement of air in ventilation.
Exhalation removes air from dead space, which is replaced.
Inhalation uses air from the dead space and fresh air.
Describe the approximate values of respiration rate, tidal volume, air to alveoli, pulmonary ventilation, and alveolar ventilation in the ideal person.
RR = 12.
TV = 500ml.
Air to alveoli = TV - 150 = 350ml.
Pulmonary ventilation = 6000ml/min (constant).
Alveolar ventilation = 4200ml/min.
Describe the changes in approximate values in an anxious and a relaxed person.
Anxious:
Higher RR.
Lower TV, air to alveoli, and alveolar ventilation (hypoventilation).
Relaxed:
Lower RR.
Higher TV, air to alveoli, and alveolar ventilation (hyperventilation).
What is partial pressure?
Gas pressure in a mixture of gases equals the percentage of that gas multiplied by the total pressure.
It increases with increasing gas concentrations.
What dilutes the value of pO2?
Dead space, residual volume, and water vapour.
Describe approximate values of pO2 and pCO2 in different scenarios of alveolar ventilation.
Normal - pO2 = 100, pCO2 = 40.
Hypoventilation - pO2 = 30, pCO2 = 100.
Hyperventilation - pO2 = 120, pCO2 = 20.
What differences in ventilation occur between the apex and base of the lung?
At the base, the volume change is greater for a given change in pressure.
Alveolar ventilation decreases with height.
What differences in compliance occur between the apex and base of the lung?
At the apex, compliance is lower, due to being more inflated at functional residual capacity.
At the base, compliance is higher, as the lungs are slightly compressed by the diaphragm on inspiration.
What differences in intra-pleural pressure occur between the apex and base of the lung?
At the base, a small change in intra-pleural pressure causes a larger change in the volume, compared to the apex.
