MODEL
Breathing: depth versus rate
Compare total and alveolar ventilation.
Model
Compare 500 mL × 12 breaths with 250 mL × 24 breaths at 150 mL dead space. Total ventilation is identical. Is alveolar ventilation?
Minute ventilation (L/min)6
Alveolar ventilation (L/min)4.2
Minute ventilation = tidal volume × frequency. Alveolar ventilation = (tidal volume − dead space) × frequency. Conducting passages contain air that does not exchange gases with blood there.
Illustrative adult values; fixed dead space. This does not calculate oxygen uptake, perfusion or disease.
Explain what you observed
How can you isolate the effect of one factor?
Saved on this browser · no online account required
Your study notes
Take the next step
Connect this activity with your lesson notes and chapter practice.
Read a related learning guide →Practise Respiration →Open the student notes folder ↗Concepts and sources
Chapter extension: selected concepts, not complete syllabus coverage.
Read the supporting source ↗PMDC curriculum ↗Questions and explanations are original teaching material; these are not official exam questions.