Physiology Lab
Name:____________________________
CONTROL OF HUMAN RESPIRATION
p1/9
Your respiratory system allows you to obtain oxygen, eliminate carbon dioxide, and regulate
the blood’s pH level. The process of taking in air is known as inspiration, while the process of
blowing out air is called expiration. A respiratory cycle consists of one inspiration and one
expiration. The rate at which your body performs a respiratory cycle is dependent on the levels
of oxygen and carbon dioxide in your blood.
Respiration rate controls the amount of CO2 blown off and therefore controls the pH of the
blood by the following equation.
CO2 + H2O H2CO3 H+ + HCO3You will monitor the respiratory patterns of one member of your group under different
conditions. The subject will breathe through a Spirometer which will measure the air flow
through it. As the subject breathes air flow will be recorded on the computer enabling you to
calculate a respiratory rate for comparison under different conditions.
Objectives:
In this experiment, you will:
• Monitor the respiratory function and ECG of an individual.
• Calculate the Respiratory Rate, Heart Rate, Tidal Volume, Vital Capacity, and FVC1
for an individual.
• Evaluate the effect of holding of breath and continual breathing of exhaled air on the
respiratory cycle.
Materials:
• Spriometer
• EKG Sensor
• EKG electrode tabs
• Lab Pro Data acquisition
system connected to a
computer.
• Plastic 5 to 7 -gallon
garage bag.
Mouth
Piece
Bacterial Filter
Spirometer
Nose Clamp
Procedure:
1. Connect the Lab Pro data acquisition system to the computer USB port, and connect the
Spirometer to Channel 1 of the Lab Pro connect the EKG sensors to Channel 2.
2. Select the Logger Pro icon. (Fig. 2) See that the
channel 1 and channel 2 buttons show
Spirometer and EKG. Make adjustments if
necessary by clicking on the channel button.
Fig. 2 Loger Pro Icon
3. Zero the Spirometer by selecting the
Spirometer channel button. Select Zero. NOTE:
The Spirometer is sensitive to orientation to
gravity. Hold it with the handle vertical for
zeroing and during the testing.
Close the dialog box.
Physiology Lab
Name:____________________________
p2/9
4. Open the Vernier data acquisition program by selecting the Clock icon,
, and set
the sample time to 8 minutes and sample rate to 10000 samples per minute.
5. Select a member of your lab group as the test subject. Place the EKG electrode tabs and
clips as shown in Fig. 1.
6. Go to Data/New Calculated Column. With the
cursor in the equation box select then select
Variables down arrow/Flow Rate. Click in the
Equation box after “Flow Rate” and make the
equation read “Flow Rate”*60. This will create
a new flow column in units of L/min instead of
L/sec. In short name type Flow, In Units type
L/min, and in Name type Flow. (See Fig. 3)
Fig. 3 Convert Flow Rate to L/min
Physiology Lab
Name:____________________________
p3/9
7. In order to plot the new calculated column: with the L/min graph, Select Options/Graph
Options/Axes Options; deselect Flow Rate and select Flow.
Part I Effect of Breath Holding
Holding one’s breath will increase the concentration of CO2 in the blood. This will shift the
above chemical reaction to the right producing more Hydrogen ions. A greater concentration of
H+ ions lowers the pH and increases the acidity of the blood.
1. Place a nose clamp on the subject and Have them sit upright in a chair and breathe
normally through the Spirometer. Do not attempt to control the breath rate or depth;
allow the autonomic system to control your breathing.
2.
While the subject is relaxed and breathing normally click collect,
, to
start collecting data. After 5 to 10 normal breaths are collected, have the subject take a
breath and hold it as long as possible. You should struggle at the end to hold your
breath absolutely as long as possible.
3. After enduring the agony of holding your breath well beyond your comfort level, relax
and breathe normally through the Spirometer. After approximately 10 breaths stop the
collection.
4. Magnify the breaths from before holding breath, by highlighting them by
clicking and dragging the grey box over the waves, and select the
magnify icon.
5. Select the Examine icon,
Place the mouse cursor on a zero
crossing of one of the first few breaths. Record the time in Table 1 in the upper left
Start Time box. Place the mouse cursor over the corresponding zero crossing of a
breath that is several breaths away. i.e. if a negative going zero crossing is used as the
start time a negative going zero crossing will be used as an end time. Record the time,
as End Time, and the number of complete breaths included in Table 1.
6. Divide the number of breaths by the minutes found by subtracting the End Time from
the Start Time and record as the Breath Rate.
Physiology Lab
Name:____________________________
p4/9
7. Find the Tidal Volume by placing the mouse cursor on a positive going zero crossing of
an exhalation wave, Click and drag the mouse to the negative going zero crossing of
that same exhalation wave and release the mouse button. There should be highlighted
section of wave with a darker grey bar on the zero line from the start to the end of the
selected exhalation wave.
Tidal Volume integration of one
exhalation wave
Exhalation
Time for 3 breaths
measured at
corresponding positive
going zero crossings
Inhalation
Fig. 4 Wave Form
End Time
Start Time
8. Select the integrate icon.
9. A box should appear in your graph showing L/min * min. This is the Tidal Volume.
Record this number in the before holding breath section of Table 1.
10. Find the heart rate before holding breath by: Place the mouse cursor over the peak of an
R wave on the EKG waveform. Record the Start time in the next start time box in Table
1 under before holding breath. Count several R waves over (the original R wave is
count zero) and position the mouse cursor over the peak of that R wave. Record the End
Time and the number of R waves in Table 1
11. Divide the number of R waves recorded by the difference between the End Time and
the Start Time. Record this number as the Heart Rate in the Beats per minute box.
12. Scroll the graph to find the breath waveforms immediately after holding breath. Repeat
steps 5-11 recording the information in Table 1 under After Holding Breath.
Start
Time
End
Time
Using 5 Beats as shown:
HeartRate =
5 Beats
EndTime − StartTime
Physiology Lab
Name:____________________________
p5/9
Table 1
Holding of Breath, Breath and Heart Rate.
Breath Rate Before
Breath Rate After
Start time
End time
Start time
End time
End time – Start time =
Number of Breaths
# _ Breaths
=
Tidal Volume =
Time _ min
Heart Rate Before
Start time
End time – Start time =
# _ Beats
=
Time _ min
End time
End time – Start time =
Number of Breaths
# _ Breaths
=
Time _ min
Tidal Volume =
Heart Rate After
Start time
Sec.
Beats/Min.
End time – Start time =
# _ Beats
=
Time _ min
End time
Sec.
Beats/Min
Questions:
1. Did the respiratory rate change after holding breath? Describe how it changed.
2. What is different about the amplitude or frequency of the respiratory waveforms
following the release of the test subject’s breath? Explain.
3. Did the heart Rate Change? Why? (If a person holds their breath significantly beyond
their comfort level epinephrine will be released from their adrenal medulla,)
Part II Ventilation – Lung Volume and Respiratory Conduction
2. Pulmonary Function Test - This test measures the amount of air that can be taken in with a
deep breath and how quickly it can be expelled from the lungs by a forceful exhalation. This
test measures the lung volumes and the respiratory air way constriction.
a. The patient places a clip over the nose and breathes through the mouth into a tube
connected to a machine known as a Spirometer. First the patient should breathe
normally for approximately 10 breaths then breath in deeply inspiring as deep and
as long as possible. And then exhales as quickly and as forcefully as possible into
the tube. The exhale should last at least six seconds though the last couple of
seconds will usually have very low velocity. I.e. the exhalation waveform should
stay above the zero line for 6 seconds. Usually the patient repeats this test three
Physiology Lab
Name:____________________________
p6/9
times, and the best of the three results is considered to be the measure of the lung
function.
b. Find the breath rate by using a few of the breaths before the deep inspiration as was
done above in Part I steps 4- 6
c. Find the tidal volume on a representative exhalation that occurred before the deep
inspiration breath by integrating one of the exhalation waves as was done in Part I
step 7 – 9. TV=__________L
d. Measure and record the Vital Capacity by integrating the forced exhalation wave
from the beginning zero crossing to where it returns to the zero line.
(VC) _____________________
e. Find the Forced Vital Capacity by first finding the Forced Expiratory Volume for
the first 1 second of maximal exhalation by integrating from the beginning zero
crossing to one second of the forced exhalation waveform.
(FEV1) _________________L
f. The Forced Vital Capacity = (FEV1 / VC) * 100% = ____________________ %
g. An average flow rate of exhalation is found between 25 to 75 % of the exhalation
waveform. By:
h. Using the Examine icon find the maximum expiratory flow at the peak of the forced
expiration wave. Forced Peak Flow = _________________L/Min
i. Calculate your Minute Volume at rest.
(TV × breaths/minute) = Minute Volume at rest _______________________L
Part III Breathing Exhaled Air
CAUTION: This test produces a mild agony (“fight or flight”) response. Do not perform
this test if you are subject to migraine headaches, asthma, or heart failure. This test will
initiate the sympathetic nervous system and cause the release of epinephrine from the
adrenal medulla. Do not attempt this experiment if you are currently suffering from a
respiratory ailment such as the cold or flu.
1. The subject will breathe in and out of the respiration bag for a period of 6 minutes. The
CO2 concentration will increase with each breath. During the 6 minute period, three
data collection runs will be performed. Between the first and second data collection, the
data from the first run will be saved for later analysis. Watch the clock to make sure the
data collection is performed at the proper times.
2. Fill the respiration bag with air and have the subject cover the Spirometer tube so that
the air does not escape.
3. Have the subject begin breathing in and out of the bag. Check to make sure that he or
she is able to easily breathe both in and out of the respiration bag. Press COLLECT to
collect data.
4. After one minute, save the data using File/Export as text, from the menu bar at the top
of the screen. Save the file to My Documents as NameRun 1 (use subject’s name or
initials in place of Name.)
5. A second sample is to be collected starting at 3 minutes and stored as NameRun 2.
6. A third sample is to be collected starting at 5.5 minutes and stored as NameRun 3
Physiology Lab
Name:____________________________
7. At the end of the sampling stop breathing into the bag.
p7/9
8. Make measurements of Breathing Rate, Heart Rate, and Tidal Volume from Run 3, and
record in the Run 3 section of Table 2, (Rows 20-26.)
9. Using File/Import/Text data recall Run 2 and measure Breathing Rate, Heart Rate,
and Respiration Amplitude from Run 2, and record in Table 2 Rows 12 - 18.
10. Using File/Import/Text data recall Run 1 and measure Breathing Rate, Heart Rate,
and Respiration Amplitude from Run 1, and record in Table 2 Rows 4 - 10.
Table 2
Breathing Exhaled Air: Tidal Volume, Breath Rate & Heart Rate
Breath Rate
Heart Rate
0 to 1 min.
End time =
Start time =
End time =
1
2
3
4
Start time =
5
6
7
End time – Start time =
Number of Breaths Measured
# _ Breaths
=
Time _ Min
8
Sec
End time – Start time =
Number of Heart Beats Measured
Breaths/Min
21
22
23
Beats/Min
(L)
11
12 Start time =
End time =
13 End time – Start time =
14 Number of Breaths Measured
15 Breaths/Min
# _ Breaths 60 _ Sec
*
=
Time _ Sec 1 _ Min
16
Tidal Volume =
20
# _ Beats
=
Time _ Min
Tidal Volume =
19
Sec
3 to 4 min.
Start time =
End time =
End time – Start time =
Number of Heart Beats Measured
Beats / Min
# _ Beats 60 _ Sec
*
=
Time _ Sec 1 _ Min
(L)
5.5 to 6 min.
Start time
End time
End time – Start time =
Number of Breaths Measured
Breaths/Min.
24
# _ Breaths 60 _ Sec
*
=
Time _ Sec 1 _ Min
Start time
Sec
End time
End time – Start time =
Number of Heart Beats Measured
Beats/Min.
# _ Beats 60 _ Sec
*
=
Time _ Sec 1 _ Min
Tidal Volume =
Summary Table (Calculated Data From Above)
Breath Rate
Tidal Volume
Heart Rate
(Breaths / Min)
L
(Beats / Min)
Start
Mid
Final
(L)
Sec
Physiology Lab
Name:____________________________
Questions:
4. Did the respiratory rate change after holding breath? Describe how it changed.
5. What is different about the amplitude or frequency of the respiratory waveforms
following the release of the test subject’s breath? Explain.
6. What would be significance of an increase in the amplitude and frequency of the
waveform while the test subject was breathing into the bag?
7. How did the respiratory waveforms and heart rate change while the test subject was
breathing exhaled air from the bag? How would you interpret this result?
8. How did the heart rate change and why?
9. Explain how Carbon dioxide affects your breathing and heart rate?
p8/9
Physiology Lab
Name:____________________________
p9/9
TEACHER INFORMATION
Construct the respiration bag used in Part II by
doing the following:
• Obtain a clean 10 – 15 gallon trash can
liner. Using masking tape, seal the open
edge shut except for a portion at one end
large enough to fit a paper or Styrofoam
cup.
• Cut the bottom out of the cup, then place the
cup in the opening of the trash can liner.
• Tape the liner around the edge of the cup
with masking tape. The only opening for air
into the bag should be through the cup.
Important: Do not attempt this experiment if you are currently suffering from a respiratory
ailment such as the cold or flu.
1. Connect the Spirometer to the Vernier computer interface.
from the Human Physiology with Vernier folder.
2. Attach the larger diameter side of a bacterial filter to the “Inlet” side of the Spirometer.
Attach a gray disposable mouthpiece to the other end of the bacterial filter