Biology Lab: Lung Capacity

Goal: To measure the amount of air in the lungs.

Equipment and Materials:

• Tub or sink that can be stoppered
• 2-liter soda bottle and cap, 1 gallon milk jug and cap
• Plastic or rubber tubing
• Marker
• A graduated measuring cup (preferably liters).

Procedure

Setup

1. Carefully fill the soda bottle all the way to the top with water and cap it. When you turn it over, there should be no air bubble at the top.
2. Fill the tub with several inches of water.
3. Turn the bottle over, submerse the top, and remove the cap. Keep the bottle under water so that no air gets into the bottle.
   
4. Push the tubing into the bottle so that one end is entirely in the bottle and the other end is outside the tub, where you can blow into it.
5. You should now be able to blow into the tubing. Air you blow in will come up in the bottle, where it can be measured. If you are able to fill an entire 2L soda jug, you may need to set up again with a gallon jug.
   

Data collection

1. RESERVE AIR: Breath in and out normally. With the air that is left in your lungs after exhaling normally, blow as much as you can into the bottle. Mark the level of water in the bottle below your air bubble.
2. Refill the bottle and repeat the procedure in #1 three times (4 total measurements). Label or number each mark -- don't remove any previous marks!
3. MAXIMUM CAPACITY: Refill the water bottle. Take as deep a breath as possible and blow all your air into the bottle. Mark the level of water below your air bubble. Note: Be careful not to hyperventilate or you may become light-headed! Rest and breath normally for at least a minute between each attempt.
4. Refill the bottle and repeat the procedure in #3 three times (4 total measurements), labelling or numbering each mark.
5. Empty the bottle and fill it to the first data line. Pour the water into your measuring cup and measure the amount of water it took to fill the bottle to the bubble line. This is the amount of air you had in the bottle for the first measurement.
6. Repeat the process in #5 for each mark.

Report

Your report should include

1. A description of your procedure in sufficient detail that another student can run your experiment
2. Your raw data, in an appropriate format.
3. Calculations of your average maximum capacity and reserve air capacity.
4. Conclusions about your lung capacity under normal and extreme circumstances.
5. An interesting additional study would be to undertake an aerobics training regime for 4-6 weeks, then repeat the above measurements to see whether your lung capacity has improved.

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