Measuring lung volumes. Syllabus reference: outline the mechanism of breathing in mammals, with...
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Transcript of Measuring lung volumes. Syllabus reference: outline the mechanism of breathing in mammals, with...
Measuring lung volumes
Syllabus reference:
outline the mechanism of breathing in mammals, with reference to the function of the rib cage, intercostal muscles and diaphragm
explain the meanings of the terms tidal volume and vital capacity
describe how a spirometer can be used to measure vital capacity, tidal volume, breathing rate and oxygen uptake
analyse and interpret data from a spirometer
Inspiration & expiration
Inspiration & expiration
Lung volumes
residual volume
Lung volumes
The maximum volume of the lungs is about 5dm3 (5 litres) although we never completely empty the lungs; even if we breathe out as much as possible (expiratory capacity) there will still be about 1.5 dm3 left in the lung (residual volume).
The amount of air breathed in and out at each breath is called the tidal volume. At rest this will be around 0.5 dm3, rising to about 2.5 dm3 when we are breathing very deeply.
The maximum volume that can be exchanged by breathing in as much as possible and then forcing out as much as possible is our vital capacity.
The spirometer
oxygen
Spirometer
Lung volumes
Note: compare to ‘inverted’ trace in textbook
Lung volumes
The spirometer
oxygen
Lung volumes; definitions
Vo
lum
e in
dm3
maximum inspiration
Inspiratory capacity
Inspiratory reserve volume
Inspiratory reserve volume
Vital capacityVital capacity
Tidal volumeTidal volume
Expiratory capacityExpiratory capacity
Residual volumeResidual volume
Total lungcapacity
Total lungcapacity
Expiratory reserve volume
Expiratory reserve volume
inspiration at restinspiration at rest
expiration at restexpiration at rest
maximum expirationmaximum expiration