Lab #5: Respiratory Physiology
1. Explain how the concentration of carbon dioxide in the blood affects its pH.
• CO 2 H O 2 H CO 2 H 3 HCO 3
• As rate of production of CO e2ceeds its rate of elimination (higher concentration), the
equilibrium shifts to the right and produces more H , which decreases pH (more acidic)
• As more frequent & deeper ventilation accelerates elimination of CO , the 2quilibrium
shifts to the left, producing less H , which increases pH (less acidic)
2. At the beginning of a period of heavy exertion, the rate and depth of breathing increases before
carbon dioxide can accumulate in the blood. What stimulates the brain to make these changes to
the pattern of breathing motions?
• 2 possible explanations:
o Exercise stimuli from contracting muscles or moving joints cause impulses to be
relayed directly to the respiratory centre to increase ventilation
o Motor impulses originating in the cerebral cortex and sent to the muscle may
cause collateral impulses to be sent to the respiratory centre to increase the
movements of ventilation
3. What is the difference between the total lung capacity and the vital capacity? What is the
difference between minute (or pulmonary) ventilation and alveolar ventilation?
• Vital capacity – maximum amount of air a person can expel from the lungs after a
maximum inspiration (inspiratory reserve volume + tidal volume + expiratory reserve
• Total Lung