Measuring Lung Volumes Flashcards
Define breathing rate.
The number of breaths per minute.
What is oxygen uptake?
The volume of oxygen absorbed by the lungs in one minute.
What is tidal volume?
The volume of air inhaled or exhaled in one breath.
When is tidal volume usually measured?
At rest.
What is a spirometer?
A device that can measure the movement of air into and out of the lungs.
What is vital capacity?
The greatest volume of air that can be expelled from the lungs after taking the deepest possible breath.
What does a float-chamber spirometer consist of?
A chamber of air or medical-grade oxygen floating on a tank of water.
What happens during inspiration to the spirometer?
During inspiration air is drawn from the chamber so that the lid moves down.
What happens to the spirometer during expiration?
The air returns to the chamber, raising the lid.
What records the movements of the spirometer?
A data logger.
What happens to the carbon-dioxide rich air?
When exhaled it is passed through a chamber of soda-lime, which absorbs the CO2.
Why is CO2 absorbed by the soda-lime?
It allows for just the oxygen consumption to be measured.
What could be wrong with the apparatus that would give invalid results?
Holes or air leaks in the tubes.
Why should the water chamber not be overfilled?
Water could potentially go into the air tubes.
What should be sterilised before every use?
The mouthpiece.
What factors affect someone’s vital capacity?
The size of the person (in particular height)
The age and gender of the person
Their level of regular exercise.
What is the average range of vital capacity?
2.5-5.0 dm^3 but may be higher in trained athletes.
What is the residual volume?
The volume of air that remains in the lungs even after forced expiration.
What is a typical tidal volume at rest?
0.5 dm^3
What does the spirometer measure?
The volume of air in the chamber.
Why does the volume of air in the chamber decrease?
Oxygen is removed and used by the body and replaced with CO2 during inspiration. The body releases CO2 during expiration which is absorbed by the soda-lime this makes the volume in the chamber go down.
What is the equation for calculating the rate of oxygen uptake?
The difference in volume between two points
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The time take for this decrease to occur.
How can the breathing rate be measured by a spirometer?
By counting the number of peaks in one minute.
What is an average breathing rate?
12-14 breaths per min
Increased oxygen uptake will result from what?
Increased breathing rate
Deeper breaths
