Core practical 17 Flashcards
What is a spirometer?
Oxygen filled chamber with a moveable lid.
How do you use a spirometer?
A person breathes through a tube connected to the oxygen chamber.
As the person breathes in the lid moves down and when they breathe out it moves up.
These movements are recorded by a pen attached to the lid of the chamber which writes on a rotating drum creating a spirometer trace.
The total volume of gas in the chamber decreases over time. This is because the air that is breathed out is a mixture of oxygen and CO2. The CO2 is absorbed by the soda lime.
How can a spirometer be used to investigate the effects of exercise?
A person breathes into a spirometer for one minute at rest and recordings are taken.
The person then exercises for 2 mins and while they’re exercising the chamber fills with oxygen again.
Immediately after the person stops exercising they breathe into the spirometer again and recordings are taken for another minute.
The recordings before and after exercise are then recorded.
What is the tidal volume on a spirometer?
Average difference in the volume of gas between each peak and trough on the trace.
How do you calculate the breathing rate on a spirometer?
Count the number of peaks in the trace in a minute.
How do you calculate oxygen consumption on a spirometer?
Find the change in volume of gas in the spirometer. (from troughs)
What is the respiratory minute volume?
Tidal volume x breathing rate
