3.1.1 (7.3) Ventilation rate/measuring (OCR A-Level Biology)

A spirometer is a device used to measure lung volume. A person using a spirometer breathes in and out of the airtight chamber, thus causing it to move up and down, leaving a trace on a graph which can then be interpreted.

• Vital capacity – the maximum volume of air that can be inhaled or exhaled in a single breath. Varies depending on gender, age, size as well as height

• Tidal volume – the volume of air we breathe in and out at each breath at rest

• Breathing rate – the number of breaths per minute, can be calculated from the spirometer trace by counting the number of peaks or troughs in a minute

Ventilation rate = tidal vol. x breathing rate