Key Terms in Spirometer Readings

Tidal volume

The volume of air in a normal breath at rest (0.5 dm³)

Vital Capacity

Maximum volume of air that can be inhaled and exhaled

Inspiratory Reserve Volume

The max volume of air that can be inhaled above the tidal volume of air

Expiratory Reserve Volume

The max volume of air that can be exhaled above the tidal volume of air

Residual Volume

The volume of air that can never be expelled from the lungs.

Total Lung Capacity

Vital Capacity + Residual Volume

Breathing Rate

The number of breaths taken per minute.

How to calculate breathing rate:

- peak to peak (or trough to trough) is one breath

- Count the number of breaths per minute

- Total air breathed per minute (pulmonary ventilation) is: tidal volume x breathing rate

Ventilation Rate

Tidal volume x Breathing rate = Pulmonary Ventilation

Oxygen Uptake

The volume of oxygen taken up by the body/lungs

Calculate oxygen uptake

- Calculate the gradient of the trace

∆y/∆x

(gradient steeper during exercise)

How does the tidal volume change with exercise?

Increases significantly