3.1.1 Exchange surfaces - Measuring Flashcards
How do you measure the capacity of the lungs?
Using:
- A peak flow meter - simple device that measures the rate at which air can be expelled from the lungs, usually used by people who have asthma.
- Vitalographs - a more sophisticated version of the peak flow meter. The patient breathes out as quick as possible and the instrument produces a graph (of the amount of air they can breath out and how quickly).
- A spirometer - used to measure different aspects of the lung volume, or to investigate breathing patterns
State the components of the lung volume
- tidal volume
- vital capacity
- inspiratory reserve volume
- expiratory reserve volume
- residual volume
- total lung capacity
Define tidal volume
Tidal volume is the volume of air that moves into and out of the lungs with each resting breath.
Around 500cm^3 in most adults at rest, about 15% of vital capacity of the lungs.
Define vital capacity
Vital capacity is the volume of air that can be breathed in when the strongest possible exhalation is followed by the deepest possible intake of breath.
Define Inspiratory reserve volume
Inspiratory reserve volume is the maximum volume of air you can breathe in over and above a normal inhalation.
Define Expiratory reserve volume
Expiratory reserve volume is the extra amount of air you can force out of your lungs over and above the normal tidal volume of air you breathe out.
Define residual volume
Residual volume is the volume of air that is left in your lungs when you have exhaled as hard as possible.
Cannot be measured directly.
Define total lung capacity
Total lung capacity is the sum of the vital capacity and the residual volume.
Define Breathing rate
The breathing rate is the number of breaths taken per minute.
Define ventilation rate
The ventilation rate is the total volume of air inhaled per minute.
What is the equation for ventilation rate?
Ventilation rate = Tidal volume X breathing rate (per minute)
