Inhalation and Exhalation

Kelly Ludwig                   Lincoln-Way High School
                               1801 East Lincoln Highway
                               New Lenox IL 60451
                               (815)485-7655

Objectives:

     The main objectives of this Mini-teach are to make a model of the  
respiratory system that will demonstrate the processes of inhalation/exhalation 
and to determine the volume of air exhaled.

Materials Needed:

                   MODEL CONSTRUCTION            VOLUME OF EXHALED AIR
    
                   2 pieces of plastic straw     food coloring
                   2 small balloons              water
                   rubber cement                 paper towel
                   clear plastic cup             2-L plastic bottle
                   large balloon                 2-hole rubber stopper
                   rubber band                   rubber tubing
                   tape                          glass tubing
                                                 graduated cylinder

Strategy:

  Model Construction
 1.  Take a piece of straw and cut a hole in the middle, do not go through to 
     the opposite side.  Fit a small balloon over each end.  If the balloons 
     are slightly larger than the straw, cement them to the ends.  Put this 
     aside to dry.
 2.  When the cement has dried, bend the straw in the middle of the hole.
 3.  Take a second piece of the straw and cut a V-shape at the end.  Fit the 
     slanted points of the straw into each semi-circle of the bent straw.
 4.  Cement the two pieces of straw together.  Allow the cement to dry.
 5.  Cut a hole in the bottom of the clear plastic cup using the diameter of 
     straw as a guide.  Push the open end of the straw into the hole of the 
     plastic cup from the inside.  Cement the straw in the hole.
 6.  Take the large balloon and cut the neck off.  Carefully stretch the cut
     balloon sheet over the opening of the cup.  Do not crack the cup.  Secure
     the balloon sheet with a rubber band.  If necessary, you may tape the 
     edges, but do not cement them to the sides of the cup.  The model will work 
     only if there are no leaks.
 7.  Pull down on the balloon sheet.  Observe what happens to the small balloons.
 8.  Push up on the balloon sheet.  Observe what happens to the small balloons.

   Measuring the Volume of Exhaled Air
 1.  Fill a plastic bottle four-fifths full of water.  Add several drops of food
     coloring to the water.  
 2.  Put a short glass tube (does not reach the water) and a long glass tube
     (almost reaches the bottom of the bottle) through the 2-hole rubber 
     stopper.  
 3.  Connect the rubber tubing.  To the short glass tube connect a piece to blow
     into.  To the long glass tube connect a piece that will touch the bottom 
     of a graduated cylinder.  
 4.  Cover the opening of the shorter length of rubber tubing with a paper 
     towel, and after inhaling normally, exhale normally into the rubber tubing.
 5.  The exhaled air will cause an equal volume of water to move through the
     outer length of tubing into the graduated cylinder.  Record the volume of 
     this water in ml in a data table.  
 6.  Pour the colored water from the cylinder into the 2-L plastic bottle.
 7.  Repeat steps 4-6 two more times.  Record the results in your data table.
     Calculate the average of the three readings.
 8.  Run in place for two minutes and exhale into the rubber tubing.  Record
     the volume of the water in the graduated cylinder.
 9.  Rest for a few minutes until your breathing returns to normal.  Then 
     repeat step 8 two times and record the results.  Calculate the average
     of the three readings.

Performance Assessment:

     At the conclusion of the Mini-teach, students will be able to answer the
following questions:
 1.  What do the small balloons represent?
 2.  What do the two ends of the straw to which the balloons are attached 
     represent?
 3.  What does the longer piece of straw represent?
 4.  What do the sides of the cup represent?
 5.  What does the balloon sheet over the cup's opening represent?
 6.  What happened to the small balloons when you pulled down on the balloon 
     sheet?
 7.  What happened to the small balloons when you pushed up on the balloon
     sheet?
 8.  What happens in the plastic bottle as you exhale into the rubber tubing?
 9.  Why is it important to measure the volume of exhaled air three times
     before and after exercise?
10.  How does your average volume of exhaled air before exercise compare to
     your average volume of exhaled air after exercise?
11.  What effect does exercise have on the volume of exhaled air?  Explain.

Conclusion:

     Students will understand the basic anatomy and physiology of the 
respiratory system.  Also, students will understand that exercise will effect
the volume of air exhaled.