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Chapter 3
Physiology of Respiration
Respiratory Physiology Class Activity 1
Lecture Discussion Questions
1. What is the difference between the abdomen and thorax in terms of ability to change
volume?
2. What is the significance of the pleural linings?
3. When the diaphragm contracts, how does it move?
4. How do we expand the thorax in respiration?
5. What does Boyle’s law state? How does that law relate to respiration?
6. How does vital capacity change with age? Since it starts declining in the early twenties, why
is it that residual volume increases at the same time? (We reach our maximum vital capacity
7. Why does the intrapleural pressure never go positive? (Intrapleural pressure is governed by
the relationship between visceral and parietal pleurae. Remind your students that the lungs
Respiration Class Activity 2
Spirometry Demonstration
If you have a spirometer on hand, use it to identify the volumes for respiration in class. If not,
you can use two-liter plastic soda bottles: Crush them, take a deep inspiration, and demonstrate
nearly filling two bottles for vital capacity (around 4,800 cc). Expiratory reserve will almost fill
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up a two-liter bottle (1,200 cc). Use a small soda bottle to relate to tidal volume (400–600 cc).
This helps students to visualize the actual measures.
Respiration Class Activity 3
Relaxation Pressure Demonstration
If you have a manometer handy, you can demonstrate development of the relaxation pressure
curve. Using a spirometer, identify your vital capacity (or that of a student). Then have the
student exhale to 80 percent of Vital Capacity (VC) and test relaxation pressure. Continue in
20percent increments and plot the results.
Respiration Class Activity 4
How Do the Capacities Relate to the Real World?
Respiration Class Activity 5
Making a Manometer
You can make a simple manometer using a plastic cup, tape, and a soda straw. Place the tape on
the glass so that it runs from top to bottom. Identify a level to which you will fill the glass with
Respiration Class Activity 6
Demonstration of Sentence without Checking Action
We require a rapid inhalation and prolonged exhalation for speech. Demonstrate a sentence that
does not utilize checking action but rather uses a 1:1 ratio of inspiration to expiration.
Respiration Class Activity 7
Respiration Rate
For adults, we expect that a person will take about seventeen breaths per minute. A nice
demonstration of this is for your students to close their eyes and count the number of breaths
they take until you tell them to stop. Ask them to count the inhalations so they don’t get
confused and count both inhalations and exhalations. You can give your students two minutes
and have them divide by two but any longer and you risk snoring! I write the numbers on the
overhead as they tell me, and then ask one of the students to do the division, since most people
have smart phones.
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Minute Volume
For adults, we expect a person to use somewhere between 5 and 8 liters per minute (average
about 6 liters). To demonstrate this, first have your students take a maximum inhalation and hold
their breath as long as they can. I use the overhead or document camera to display my watch (or
stopwatch, if I’m unusually prepared for class) and a tally sheet. Students can keep track of when
they have to breathe, and then you can tally the times. This is a good reflection of how much
oxygen/air their bodies need. Remind them that they inhaled maximally, so their total lung
capacity was about 6 liters (6,000 cc). I’m 65 years old at this point, and can hold my breath for
about 60 seconds without too much distress, so your students should come up with numbers that
are in that range as well. What does this represent? Total lung capacity is about 6,000 cc, and
that is what I have to work with for gas exchange. If minute volume is about 6 liters, and I have
to breathe after a minute, that is a pretty good reflection of my air requirements.
Respiration Class Activity 6
Videos and Guest Lectures
I tend to intersperse clincal videos with the course content as time goes by. Most of these are
more supportive of physiology, but may be useful as you are presenting anatomy content. I’m
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format, which I now place on a Health Information Portability and Accountability Act (HIPAA)
compliant, portable drive. I use this drive for all of my portable media content, since some of it
includes client videos. Having a solid password protected drive has helped me sleep better at
night!). When I get a digital video disc (DVD) from an agency or vendor, such as the Passy-Muir
video, I’ll often use a screen-capture program such as Snagit and edit the file in Camtasia for my
use in class. You are probably much more tech savy and can rip a DVD, but that’s beyond my
skill level!
I use a Learning Management System (LMS) for course augmentation in all my classes
(Moodle at my university), so I will also place the video on the LMS course site. If you are using
Camtasia you can get easy streaming, so students can see what you show in class any time. I
don’t place clinical videos online in the LMS, and I have all students sign a confidentiality
statement when class starts, even though they have all been HIPAA trained. The statement
(included in these materials for your use if you wish) reminds students of the privileged nature of
their area of study.
Some other sources include agencies such as the Multiple Sclerosis (MS) society,
Parkinson’s foundation, and other neurogenic sites. I would also strongly suggest grazing
through YouTube if you don’t already do that. You have to kiss quite a few frogs to find a
prince, but more and more you’ll find that organizations use it as a screening stage for their
videos. Please note copyright restrictions before digitizing, although I have found the Passy-Muir
group and others to be quite amenable to this process for educational purposes. If you drop an
Physical therapist: A local PT could lecture on co-treatment with SLPs, as well as issues such as
poststroke rehabilitation, fatigue, transfers, and other medically oriented issues.