Roche A. Samy
Measuring Tidal Volume-Lung Capacity (Human Lungs)
How to set up an experiment to measure lung capacity
You will need a one-gallon jug or bottle, a large graduated cylinder or a large measuring cup, a two hole rubber stopper to fit the jug, glass tubing (to fit through the holes of the stopper), rubber tubing to fit around the glass tubing, pencil and notebook for record keeping and a graph paper.
Set up the apparatus as shown in Appendix B.
Use bent glass tubes and insert the tubing into the stopper after lubricating the tubes with water or soap solution. It is best to lubricate the holes in the stopper as well. Insert the glass tubes with a very gentle turning motion. Prior to inserting the stopper, fill the jug to about 3/4 of water and slightly color it with safe food color.
Ask one of the students to exhale normally into the rubber tube. The pressure of the exhaled air will force water from the jug into the graduated cylinder. Record how much water passes into the cylinder. This is a measure of the student’s
TIDAL VOLUME.
Repeat the experiment for every student in class. You may also want to collect data of measurements by subject group athletes, nonathletes, students of various heights, or ages, smokers or non-smokers, etc. Ask the students to draw a graph and try to plot and pick out the various subject groups mentioned above.
In this activity, the students will focus on one breathing process that they can measure and that may play a role in habitat adaptations like mountain living or high altitudes, several hundreds of feet above sea level. This procedure has to do with how much air is inhaled (or exhaled) with each breath. This measurement is what scientists call as tidal volume.
Unlike total lung capacity, the total space that can be filled in the lungs-tidal volume is a measurement of only that amount of air that ebbs and flows with breathing. This can be compared to measuring the tides of an ocean. The only difference here is that you are not measuring all the water in the ocean but only the water that runs up the beach at high tide and down the beach at low tide.
Scientific Facts That Students May Be Interested
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1). It has been found that the lungs of Peruvian Indians who live in the high altitudes of the Andes Mountains hold more air than do the lungs of people who live at sea level.
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2). Small animals including rats and mice have more red blood cells than rats and mice that live in the valley or lowlands.
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3). When athletes run long distances at high altitudes track coaches have found that the athletes trained at high altitudes run faster than do athletes trained at low altitudes.
Evaluation:
Questions:
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1). What do the above three facts have in common?
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2). What does adaptation to habitat mean?
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3). How can you measure your lung capacity?
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4). What is the average tidal volume of all the class?
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5). What is the average tidal volume of each of the groups?
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6). What is the apparent relationship between tidal volume and “life style” of:
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a) athletes
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b) smokers
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c) students having cold
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d) different ages of students.
