LUNG VOLUMES AND CAPACITIES
STANDARDS
•
•
•
3.1.10A, 3.1.12A – Identify the function of
subsystems within a larger system; analyze and
Westminster College
describe the function, interaction and relationship
among subsystems and the system itself.
3.1.10B - Apply mathematical models to science and technology.
3.3.10A, 3.3.12A - Explain the relationship between structure and function at the
molecular and cellular levels; explain and analyze the relationship between
structure and function at the molecular, cellular and organ-system level.
INTRODUCTION
Measurement of lung volumes provides a tool for understanding normal function of the
lungs as well as disease states. The breathing cycle is initiated by expansion of the chest.
Contraction of the diaphragm causes it to flatten downward. If chest muscles are used, the
ribs expand outward. The resulting increase in chest volume creates a negative pressure
that draws air in through the nose and mouth. Normal exhalation is passive, resulting
from “recoil” of the chest wall, diaphragm, and lung tissue.
In normal breathing at rest, approximately one-tenth of the total lung capacity is used.
Greater amounts are used as needed (i.e., with exercise). The following terms are used to
describe lung volumes (see Figure 1):
Tidal Volume (TV):
The volume of air breathed in and out without
conscious effort
Inspiratory Reserve Volume (IRV): The additional volume of air that can be inhaled
with maximum effort after a normal inspiration
Expiratory Reserve Volume (ERV): The additional volume of air that can be forcibly
exhaled after normal exhalation
Vital Capacity (VC):
The total volume of air that can be exhaled after
a maximum inhalation: VC = TV + IRV + ERV
Residual Volume (RV):
The volume of air remaining in the lungs after
maximum exhalation (the lungs can never be
completely emptied)
Total Lung Capacity (TLC):
= VC + RV
Minute Ventilation:
The volume of air breathed in 1 minute:
(TV)(breaths/minute)
In this experiment, you will measure lung volumes during normal breathing and with
maximum effort. You will correlate lung volumes with a variety of clinical scenarios.
Westminster College SIM
Page 1
Lung Volumes and Capacities
GUIDING QUESTIONS
• What do the peaks on the experimental
graph represent in terms of lung volume and
capacity?
• Is there a difference in lung capacity
between men and women?
• What type of clinical respiratory conditions
could affect lung capacity?
SAFETY
•
•
Do not attempt this experiment if you are
currently suffering from a respiratory
ailment such as the cold or flu.
Figure 1
Do not attempt this experiment if you have a known chronic respiratory ailment.
MATERIALS
LabQuest
LabQuest App
Vernier Spirometer
disposable mouthpiece
disposable bacterial filter
nose clip and tissues
PROCEDURE
1. Connect the Spirometer to the LabQuest and turn it on by pressing the oval Power
button at the top left of the equipment. Choose New from the File menu.
2. On the Meter screen
, tap the Rate box at the right of the screen. A Data Collection
screen will appear. Change the data-collection rate to 100 samples/second and the datacollection length to 60 seconds. Select OK.
3. 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 (see Figure 2).
4. Have the subject sit down in
a comfortable position. Hold the
Spirometer in one or both hands.
Figure 2
Brace your arm(s) against a
solid surface, such as a table, and choose Zero from the Sensors menu.
Note: The Spirometer must be held straight up and down, as in Figure 2, and not moved
during data collection.
Westminster College SIM
Page 2
Lung Volumes and Capacities
5. Tap the Graph tab
.
A graph of Time (s) vs. Flow Rate (L/s) will appear.
6. Collect inhalation and exhalation data.
a. Place a tissue or Kimwipe over your nose, then put on the nose plug.
b. Start data collection by tapping the Start icon
(lower left of the screen).
c. Taking normal breaths, begin data collection with an inhalation and continue to
breathe in and out. After 4 cycles of
normal inspirations and expirations
Figure 3. Flow Rate Graph
fill your lungs as deeply as possible
(maximum inspiration) and exhale as
fully as possible (maximum
expiration). It is essential that
maximum effort be expended when
performing tests of lung volumes.
d. Follow this with at least one
additional recovery breath. Continue
to take normal breaths until the full
60 s is complete. The LabQuest will
automatically stop taking data. Your
graph should look something like
Fig. 3.
7. Store the lung volume and capacity data by tapping the Cabinet icon . Tap the Run 2
box to the top right of the screen, and select Run 1 to see the graph of the data.
8. To view a graph of volume vs. time, tap the
y-axis label (Flow Rate (L/s)) and select
Volume from the drop down menu. The graph
may take a few seconds to appear.
9. If the baseline on your graph has drifted (see
sloping graph in Fig. 4A), choose Baseline
Adjustment from the Analyze menu.
The screen shown in Fig. 4a will appear. To
bring the baseline volumes closer to level, use
the ▼and ▲ Adjustment buttons to move the
baseline. The LabQuest may be slow to readjust
the baseline. Wait 5-10 sec to see the baseline
change. Select OK when finished.
Figure 4. Lung Volume Graph
A. Baseline Adjustment Screen
B. Adjusted Lung Volume Graph
10. The LabQuest will automatically rescale the
graph, and you should have a screen that looks
like Figure 4B. If the baseline is still a little off,
you may repeat Step 9 to readjust it.
Westminster College SIM
Page 3
Lung Volumes and Capacities
11. Determine the Δy for the Tidal Volume portion of your graph.
a. Select a representative peak and valley in the Tidal Volume (TV) portion of
your graph.
b. Tap the peak (upper
Figure 5. Calculation of Tidal Volume
blue arrow) and note
the maximum volume
value to the right of the
screen.
c. Tap the bottom of the
valley (lower blue
arrow) that follows it
and note the minimum
volume value.
d. Calculate the Δy
value and record it, to
the nearest 0.1 L, as the
total Tidal Volume in
Table 1.
TV = (max. peak volume) – (min. valley volume)
TV = ________________ - _________________
12. Determine the Δy
for the Inspiratory
Figure 6. Calculation of Inspiratory Reserve Volume
Reserve Volume (Fig.
6).
a. Tap the peak that
represents your
maximum
inspiration (blue
arrow) and note the
volume value.
b. Using the
average level of the
peaks (blue dashed
line) graphed during
normal breathing
IRV = (max. peak of inhalation) – (avg. peak of tidal volume)
from Step 6c,
calculate the Δy
value:
IRV = ________________ - _________________
c. Record the Δy, to
the nearest 0.1 L, as
the total Inspiratory Reserve Volume in Table 1.
Westminster College SIM
Page 4
Lung Volumes and Capacities
13. Determine the Δy for the Expiratory Reserve Volume (ERV).
a. Tap the valley (blue arrow) that represents your maximum expiration and note
the volume value.
b. Using the average level of the valleys (blue dashed line) graphed during normal
breathing from Step 9, calculate the Δy value:
Figure 7. Calculation of Expiratory Reserve Volume
ERV = (max. valley of inhalation) – (avg. valley of tidal volume)
IRV = ________________ - _________________
c. Record the ERV, to the nearest 0.1 L, as the total Expiratory Reserve Volume
in Table 1.
14. Calculate the Vital Capacity and enter the total to the nearest 0.1 L in Table 1.
Calculation of Vital Capacity
VC = TV + IRV + ERV
VC = ______ + ______ + ______ = ________
15. Calculate the Total Lung Capacity (TLC) and enter the total to the nearest 0.1 L in
Table 1. (Use the value of 1.5 L for the RV.)
Westminster College SIM
Page 5
Lung Volumes and Capacities
Calculation of Total Lung Capacity
TLC = VC +
RV
TLC = ______ + __1.5__ = ________
16. Share your data with your classmates and complete the Class Average columns in
Table 1.
17. Exit out of the LabQuest Application by choosing Quit from the File menu. Turn the
LabQuest off by holding down the oval Power button until the screen goes dark. Place
the LabQuest and power supply back in the small pencil case. Throw away all of the
cardboard tubes and bacterial filters that were used during the experiment.
REFERENCES
Diana Gordon and Steven L. Gordon, M.D. 2005. Human Physiology with Vernier.
Experiment 8: Blood Pressure and Exercise. Vernier Software & Technology.
Beaverton, OR. Pp 19-1 – 19-5, 19-1T – 19-2T.
CREDITS
The lab was adapted and revised by Dr. Stephanie Corrette-Bennett.
Westminster College SIM
Page 6
Lung Volumes and Capacities
DATA SHEET
Name: _______________________
Group: _______________________
Date: _______________________
Volume measurement
(L)
Tidal Volume (TV)
Inspiratory Reserve
(IRV)
Expiratory Reserve
(ERV)
Vital Capacity (VC)
Residual Volume (RV)
Total Lung Capacity
(TLC)
Individual
(L)
Table 1
Class Average (Male
in L)
Class Average (Female
in L)
≈1.5
≈1.5
≈1.5
DATA ANALYSIS
1. What was your Tidal Volume (TV)? What would you expect your TV to be if you
inhaled a foreign object which completely obstructed your right mainstem bronchus?
2. Describe the difference between lung volumes for males and females. What might
account for this?
3. Calculate your Minute Volume at rest.
(TV × breaths/minute) = Minute Volume at rest
Westminster College SIM
Page 7
Lung Volumes and Capacities
If you are taking shallow breaths (TV = 0.20 L) to avoid severe pain from rib fractures,
what respiratory rate will be required to achieve the same minute volume?
4. Exposure to occupational hazards such as coal dust, silica dust, and asbestos may lead
to fibrosis, or scarring of lung tissue. With this condition, the lungs become stiff and have
more “recoil.” What would happen to TLC and VC under these conditions?
5.
In severe emphysema there is destruction of lung tissue and reduced recoil. What
would you expect to happen to TLC and VC?
6.
What would you expect to happen to your Expiratory Reserve Volume when you
are treading water in a lake?
Westminster College SIM
Page 8