�0 GCSE Additional Science Copymaster File © Edexcel Limited 2007

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Changes in breathing are measured using a spirometer (spiro means ‘to breathe’). The diagram shows a spirometer. The results are recorded on a paper chart.

You can make a simple model to show how a spirometer works.

How can you measure your breathing?

B2.1 7a

Sheet 1 of 2

��GCSE Additional Science Copymaster File© Edexcel Limited 2007

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Results

Volume of air in bottle

1st breath (cm3)

2nd breath (cm3)

3rd breath (cm3)

4th breath (cm3)

5th breath (cm3)

Average (cm3)

After breathing in

After breathing out

Difference in volume

1 What happens to the bottle when you breathe in?

2 What happens to the bottle when you breathe out?

3 Why is it important to pinch your nose during this experiment?

4 Calculate the average difference in volume between in and out breaths. This is called your tidal volume.

5 Multiply your breathing rate by your tidal volume to find your ventilation rate.

6 Calculate how many dm3 of air move in and out of your lungs in 1 minute. Show your working.

7 a State two ways in which you can increase your ventilation rate.

b When would it be necessary to increase your ventilation rate? Explain why.

Method Apparatus

A Measure 500 cm3 of water and pour it into the plastic bottle. Mark the water level on the bottle with a permanent marker.

B Add another 500 cm3 and mark this 1 dm3. Repeat until you have made marks every 500 cm3 up to 3 dm3. Empty the bottle.

C Cut a large hole in the bottom of the bottle with the scissors, and fit the plastic tube into the hole.

D Push the tube in until it reaches the top of the bottle and tie it in place with thread (pass the thread through the top of the bottle and screw on the cap). Disinfect the other end of the tube (the bit that will go into your mouth) by placing it in the disinfectant solution.

E Place the bottle in a deep container (e.g. a bucket or sink) which is half full of water. The bottle must be supported loosely to keep it upright and stop it from tipping over.

F Copy the table below to record your results.

G Lower the bottle until the water fills the inside to the 1 dm3 mark.

H Now pinch your nose and gently breathe in and then out of the pipe. Record the changes in the amount of air in the bottle as you breathe in and out normally.

I Do this for 5 breaths and record all your results in your table.

J Count how many breaths you take in 1 minute. This is your breathing rate.

Take care when

using scissors to pierce the bottle.

3-litre PET bottle (clear, screw-topped plastic fizzy drink bottle)

scissorsmeasuring jug or cylinder calibrated

in mlwater1–1.5 m wide corrugated plastic

tubing

short lengths of plastic tubing with slightly smaller or larger diameter than the main tube (to use as mouth pieces)

piece of thread dilute disinfectant (e.g. Milton)permanent marker pendeep bucket or sink half full of water

B2.1 7a

How can you measure your breathing? (continued)

Sheet 2 of 2