Experiment 1
Warming Function of Nasal
Passageways
Nasal passageways transport air to and from the lungs and also serve to warm and humidify this
air. The nasal turbinates provide a large surface area and rich blood supply for a process of heat
exchange which contributes to the maintenance of a constant body temperature (see Figure 1).
Warming of inhaled air improves lung function and removal of heat from the exhaled air helps to
prevent excessive heat loss from the body. Conditions such as viral infections, allergies, and
deviated septae can all lead to plugging of nasal passageways and mouth breathing. Inhaling
colder air through the mouth can irritate the lungs and worsen conditions such as bronchitis and
asthma.
Front view
Side view
Figure 1
In this experiment, you will use the Vernier Surface Temperature Sensor to measure the
temperature of exhaled air. Air that has passed through the nasal passageways will be compared
with air that was inhaled through the mouth. In both cases, the air spends time in the lungs where
heat is acquired from exposure to the extensive lung tissue alveolar surface area (see Figure 2).
However, air that has passed through the nasal passageways arrives at the lungs already partially
warmed.
Figure 2
Human Physiology with Vernier
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Experiment 1
OBJECTIVES
In this experiment, you will

Compare the temperature of air that has passed through the nasal passageways with air that
has not.
 Evaluate the contribution of nasal passages vs. lungs to the warming of the air we breathe.
MATERIALS
computer
Vernier computer interface
Logger Pro
Vernier Surface Temperature Sensor
plastic straws
tape
PROCEDURE
Comparison of Temperature of Air Inhaled Through Nose and Air Inhaled Through Mouth.
1. Connect the Surface Temperature Sensor to the Vernier computer interface. Open the file
“01 Warming Function” from the Human Physiology with Vernier folder.
2. Insert the end of the Surface Temperature Sensor in one end of a
plastic straw such that the tip of the sensor is approximately
2 cm into the straw. Fold the wire back over the straw and affix
it to the outside of the straw with tape (see Figure 3).
3. Click
to begin data collection. Record a baseline
temperature for approximately 5 s or until a stable baseline
temperature is reached.
Figure 3
4. After the baseline temperature has stabilized, begin taking normal breaths through the nose
and exhaling by blowing your breath out the mouth and through the straw (approximately
2–3 s per inhalation and 2–3 s per exhalation). Remove the straw from the mouth after each
exhalation. Continue this process until data collection is complete. Data will be collected for
40 s.
5. Store this run by choosing Store Latest Run from the Experiment menu.
6. Click
to establish a temperature baseline. If the temperature is higher than the baseline
temperature of the first run, allow the baseline temperature to fall to a level close to what it
was at the start of the first run. You may speed this process by inhaling and/or blowing
through the straw. Once your baseline temperature has been reached, click
.
7. Click
to begin data collection. Record a baseline temperature for about 5 s.
8. After the baseline temperature has stabilized, begin taking normal breaths through the mouth
and exhaling through the straw (approximately 2–3 s per inhalation and 2–3 s per exhalation).
Use a nose clip or pinch the nose closed to prevent accidental nose breathing. Remove the
straw from the mouth during each inhalation. Continue this process until data collection is
complete. Data will be collected for 40 s.
9. Click the Statistics button, . Check the boxes in front of Latest and Run 1, then click
. Record the maximum and minimum temperatures to the nearest 0.1°C for each run
in Table 1.
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Human Physiology with Vernier
Warming Function of Nasal Passageways
10. Subtract minimum from maximum values to obtain the temperature change and record these
values as ∆t. Then, subtract the ∆t values for mouth inhalation (Latest) from nose inhalation
(Run 1) and record this value in the column labeled ∆t Run 1 – ∆t Latest.
DATA
Table 1
Run 1
(nose inhalation)
Latest
(mouth inhalation)
∆tRun 1 – ∆tLatest
Maximum temperature (°C)
Minimum temperature (°C)
∆t (°C)
DATA ANALYSIS
1. Reviewing your data, what conclusions can you reach regarding where inhaled air receives
most of its heat?
2. What proportion of the difference in temperature between inhaled and exhaled air can be
attributed to the nasal passageways when nose breathing? Assume that the warming
contribution of the mouth is negligible. (For the denominator, use the ∆t value for Run 1 in
Table 1).
3. The average surface area of the nasal passageways is 160 cm2 and the average surface area of
the alveoli in the lungs is approximately 100 m2 (1  106 cm2). Use the data you collected to
calculate the amount of heat contribution per unit area of
(a) nasal epithelium surface area to which the air is exposed.
(b) alveolar surface area to which the air is exposed.
In both cases, ignore confounding variables such as the volume of air that stays in the bronchi
(also called dead space) and the volume of air that does not leave the lungs, also called
functional residual capacity.
4. Describe a situation in which it would be beneficial to breathe through the mouth.
Human Physiology with Vernier
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