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Abstract

During the breathing cycle, air is inhaled, distributed throughout the lungs, and then exhaled. Lung volume includes a group of measures that quantify the amount of air that is inhaled or exhaled during both normal breathing and forceful breathing. In this experiment, you will be working with two of these measurements: Tidal Volume (TV): volume of air inhaled or exhaled during under normal breathing and Expiratory Reserve Volume (ERV), the amount of residual air that is exhaled under more forceful breathing. Measurements of lung volume will be conducted on a group of participants, from which you will determine if there is a difference in lung capacity between genders.

Hypothesis

Boys will have a (higher/lower) lung volume than girls

Objective

• Create a hypothesis for which gender has the largest lung volume. • Conduct an experiment to measure the lung volume of participants. • Collect data by recording the lung volume of participants. • Analyze the collected data. • Form a conclusion as to whether there are differences in lung volume, between genders.

Background

When breathing in air (inhalation), the lungs fill up with air, from which oxygen is extracted. When exhaling, air is released from the lungs in the form of carbon dioxide. The amount of air held by the lungs is lung volume. Lung volume varies based on the individual. Size, gender, health, age, ethnicity, and geographical location are all factors that cause variation in lung volume. Tall people have a larger lung volume than short people. Being athletic and in good shape increases your lung volume, while health conditions or the lack of exercise can reduce it. People who live in high altitudes will have a larger lung volume than those who live at sea level. In this experiment, you will compare the lung volumes between genders, while eliminating the differences caused by the previously mentioned variables.

Scientific Terms

Lung volume , Tidal Volume (TV) , Expiratory Reserve Volume (ERV)

Materials

Supply of balloons (all equal in size)
20 participants (10 males and 10 females of approximately same age)
A piece of string, about 1 meter in length.
Ruler
Lung volume table (provided).
Data table (provided).

Procedure

Establish your hypothesis: For example - “Boys will have a (higher/lower) lung volume than girls.”

Groups 

Divide the participants into two groups: 10 males and 10 females. The individuals of these groups should be of approximately the same age and have no history of asthma, bronchitis, or other health problems.

Lung Volume

Tidal Volume (TV)

  1. To obtain the participant’s tidal volume, have the individual breath normally into a balloon.
  2. Have the participant pinch off the end of the balloon to prevent air from escaping. 
  3. Wrap the string around the balloon once in order to obtain the balloon’s circumference.
  4. Remove the string from around the balloon and lay the string out straight along the ruler to get the measurements of the string.
  5. Write down the measurement on a separate sheet of paper.
  6. Check the measurement against the “Lung Volume Conversion Table” to obtain the corresponding lung volume.
  7. Record the lung volume on the separate sheet of paper.
  8. Repeat these steps with the participant two more times.
  9. Find the average lung volume of each participant by adding the three lung volume amounts and dividing by three.
  10. Record the average tidal volume on the “Lung Volume” data sheet.
  11. Repeat these procedures with all participants.

lung capacity experiment

Expiratory Reserve Volume (ERV)

  1. To obtain the participant’s expiratory reserve volume, have the participant practice breathing in deeply and exhaling fully.
  2. When the participant is ready, have them take a normal breath in the balloon (you will not count this breath in the experiment) followed by taking a deep breath, then forcefully exhaling into the balloon.
  3. Have the participant pinch off the end of the balloon to prevent air from escaping. 
  4. Wrap the string around the balloon one time in order to obtain the balloon’s circumference.
  5. Remove the string from around the balloon and lay the string out straight along the ruler to get the measurements of the string.
  6. Write down the measurement on a separate sheet of paper.
  7. Check the measurement against the “Lung Volume Conversion Table” to get corresponding lung volume.
  8. Record the lung volume on a separate sheet of paper.
  9. Repeat these steps with the participant two more times.
  10. Find the average lung volume of each participant by adding the three lung volume amounts and dividing by three.
  11. Record the average tidal volume on the “Lung Volume” data sheet.
  12. Repeat these procedures with all participants.
  13. Determine if the results support your hypothesis.

 

Lung Volume Conversion Table

Balloon Diameter centimeters

Lung Volume Cubic centimeters

12

1,000

13

1,250

14

1,500

15

2,000

16

2,250

17

2,500

18

3,000

19

3,500

20

4,000

21

4,500

22

5,500

23

6,000

24

7,000


Lung Volume Data Sheet

Male

TV

ERV

Female

TV

ERV

Participant 1

   

Participant 1

   

Participant 2

   

Participant 2

   

Participant 3

   

Participant 3

   

Participant 4

   

Participant 4

   

Participant 5

   

Participant 5

   

Participant 6

   

Participant 6

   

Participant 7

   

Participant 7

   

Participant 8

   

Participant 8

   

Participant 9

   

Participant 9

   

Participant 10

   

Participant 10

   

 

Discussion

The larger the volume of a participant’s lungs, the more air he or she blows into the balloon. Hence, the larger the balloon, the greater the volume, as indicated in the volume table. Refer to the illustration.  In the measurement and recording of lung volume, would the shape of the balloon matter? How do you think it would affect your measurements?

We’ve already mentioned that all participants should be of the same age, and should have no ailments. What are some other variables that should be controlled, in the experiment? For example, does it matter whether all participants use the same type of balloon, made from the same material? What about the color of the balloons? How about the temperature and humidity of the surrounding environment?

Also consider

Repeat the experiment over a wide range of age groups and ethnicities 

References

“What Should I Know about Lung Capacity?” on the Wise Geek web site http://www.wisegeek.org/what-should-i-know-about-lung-capacity.htm

“Respiratory or Lung Volumes and Capacities” at GetBodySmart http://www.getbodysmart.com/ap/respiratorysystem/physiology/spirometry/volumescapacities/animation.html

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