Biology investigation - investigating the relationship between the breathing rate and the carbon dioxide concentration of exhaled air

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James Fung         18thJanuary,2002

Biology investigation – investigating the relationship between the breathing rate and the carbon dioxide concentration of exhaled air

Result:

Fig.2

Analysis:

For those 5 sets of data I have got, I have drawn them up on Fig.1. Then I have chosen the one from person E to analyse further, which gives Fig.2.

There are some chemoreceptors, which are situated in the medulla of the brain, the arch of the aorta and in the wall of the carotid arteries. And they are stimulated when there is an increase in carbon dioxide level inside our body. Then a nerve impulse is sent to the breathing system by these chemoreceptors in order to regulate the breathing rate.

In response to an increase in the concentration of carbon dioxide, the inspiratory centre increases the rate of nerve impulse sent to the inspiratory muscles. This results in an increase in both the rate and depth of breathing.

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The regulation of breathing is an example of homeostasis. When the concentration of carbon dioxide rises this stimulates an increase in breathing rate, which in turn reduces the concentration of carbon dioxide, leading to a decrease in breathing rate.

Fig.2 shows a trend that as the carbon dioxide concentration increases from 6% to 31%, the breathing rate increases from 15 to 25 breaths per minutes. This trend is expected and fully support the biological theory described above.

i.e. Increases in carbon dioxide concentration level       Detected by chemoreceptors

       Increased ...

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