Transcript Lab 8 – Respiratory System (Part 2 – Physiology)

Lab 8 – Respiratory System (Part 2 –
Physiology)
Dr. Kim Wilson
Textbook Reference – Exercise 37A
 Pg. 549
 Spirometry video
PART A: CHEST MEASUREMENTS
 INSTRUCTIONS:
 1. Complete Exercise 1 included in this handout and record
all the data you collect on the Results Sheet.
 2. Answer related questions on the Questions Sheet.
PART B: RESPIRATORY (PULMONARY)
VOLUMES
 Spirometer - an instrument used to measure different volumes
of air involved in breathing.
 The wet spirometer (there are other types) is designed specifically
for use in undergraduate life sciences laboratories since it is sturdy,
compact, and easy to use.
 Based on the mechanical principle that air, exhaled from the lungs,
will cause displacement of a closed chamber which is partially
submerged in a liquid.
 The spirometer consists of 2 vessels:
 A larger vessel containing water and having a breathing tube attached to it
 A smaller vessel inverted & suspended in the water.
 A counterweight and indicator are attached to the inverted chamber.
Air blown into the inverted chamber will cause it to rise and move
the indicator along a scale, which is calibrated in liters, to give lung
volume measurements.
Instructions
 1.Vital Capacity, will be measured using the spirometer.
 Following this, Tidal Volume, Expiratory Reserve Volume, Inspiratory




Reserve Volume and Respiratory Minute Volume will be calculated.
Always be certain that the indicator is set on zero before beginning
any of these tests.
Always exhale into the spirometer, never inhale!
When measuring lung volumes, the person being tested should look
away from the scale; have your partner read and record the results.
The Spirometer will record lung volumes in liters; it will be
necessary, to convert to milliliters (ml) using the following formula:
1 liter = 1000 ml
Vital Capacity (VC)
 The largest volume of air an individual can move in & out of
his/her lungs
 VC = Inspiratory Reserve Volume (IRV) + Tidal Volume
(TV) + Expiratory Reserve Volume (ERV).
How to Measure VC:
 The person being tested should stand erect and breath in and out
slowly and deeply for a short time. Following this, the person
should breath in as deeply as possible, place the spirometer
mouthpiece into the mouth, block the nose, and exhale as forcibly
as possible while looking away from the scale. The result should
then be read, converted to ml, and recorded on the Results
Sheet. Following this, the procedure should be repeated twice,
read and recorded in ml. Finally an average of the three readings
should be obtained and recorded on the Results Sheet.
 Note: If one reading is obviously variant, repeat the test for that
particular reading. Once the average VC has been determined,
compare it to the tables which list average normals based on sex,
age and height. (Additional Handout)
Other Formulas
 Tidal Volume (TV)
 Volume of air exhaled after a normal inspiration
 How to Calculate TV: See Results Sheet
 Expiratory Reserve Volume (ERV):
 Largest additional volume one can forcibly expire after expiring TV
 How to Calculate ERV: See Results Sheet
 Inspiratory Reserve Volume (IRV):
 Amount of air that can be forcibly inspired after normal inspiration
 How to Calculate IRV: See Results Sheet
 Respiratory Minute Volume (RMV):
 Amount of air moved into the lungs per minute
 How to Calculate RMV: See Results Sheet
PART C: THE EFFECT OF CARBON DIOXIDE
ON THE RESPIRATORY CONTROL CENTERS
 INSTRUCTIONS:
 1.
Complete Exercise 2 included in this handout and
record the data you collect on the Results Sheet. Keep in
mind that the respiratory control centers are very sensitive to
even slight changes in the CO2 content of the blood, and that
high levels of CO2 serve as the MAJOR stimulus to inhale.
 2. Answer related questions on the Questions Sheet.
PART D: RESPIRATORY RATE AND
SOUNDS OF NORMAL BREATHING
 INSTRUCTIONS:
 1. Count the number of times your partner breathes per minute by watching
the movement of the chest. Ideally he/she should be distracted and not know
that you are counting the respiratory rate. Record the rate of quiet respiration
on the Results Sheet. Obtain a stethoscope, clean the earpieces with an alcohol
swab and listen to the sounds of quiet breathing (by your partner) over the
larynx, trachea, and front, sides, and back of the chest. (If the room is noisy,
find a quiet location.) Record results on Results Sheet. Have your partner
vigorously exercise for a full 3 minutes, then count the respiratory rate again.
Record the rate of respiration after exercise on the Results Sheet. Use the
stethoscope and listen to larynx, trachea, and chest (front, sides and back) as
before. Record results on Results Sheet. Clean Stethoscope earpieces with
alcohol when finished.
 2. Answer related questions on the Questions Sheet.
PART E: TEMPERATURE AND
COMPOSITION OF EXHALED AIR
 INTRODUCTION:
 The respiratory system modifies air by cleansing, warming and
humidifying it. When carbon dioxide combines with water an acid
(known as carbonic acid) is formed in the following manner: CO2
+ H20----- H2Co3 (carbonic acid). An increased amount of
carbonic acid blown out by the lungs can lead to an alkaline
condition within the body (respiratory alkalosis). Complete the
following exercise using the formulas below to convert between
Fahrenheit & Celsius.
 Celsius = 5/9 (Fo-32)
 Fahrenheit = 9/5 Co + 32
INSTRUCTIONS
 1. Using a chemical thermometer, determine room temperature. Record the results on
the Results Sheet. Note: Chemical thermometers are different from clinical
thermometers; do not shake the mercury down!
 2. Hold the bulb of the thermometer between the lips about an inch into the mouth. The
bulb should not be touching any part of your body.
 3. Exhale air rapidly over the bulb of the thermometer & immediately take a
temperature reading. Record the results on the Results Sheet.
 4. Exhale air on a glass plate. Record the results on the Results Sheet.
 5. Place a small amount of a prepared solution of bromothymol blue in a beaker. Using a
straw, gently blow air into the solution, causing it to bubble. Be careful not to suck the
solution into your mouth. The bromothymol blue is a pH indicator. It is blue under
alkaline conditions and turns green to yellow as the solution becomes more acid.
Record the results on the Results Sheet.
 6. Answer related questions on the Questions Sheet.
EXERCISE 1: CHEST MEASUREMENTS
 DISCUSSION:
 In inspiration, due to the contraction of muscles in the
thorax, the size of the thoracic cavity increases. This causes
an increase in the size of the lungs, lowering the air pressure
inside the lungs. The decrease in air pressure inside the lungs
causes air to enter the lungs. This constitutes inspiration.
During expiration, the muscles of the thorax relax, the chest
size decreases, and air leaves the lungs.
Procedure
 1. Using the tape measure, determine the circumference of the chest in





inches at the axillae. To do this, place the tape around the chest as high
up under the armpits as possible during each of the following
conditions: at the end of a QUIET inspiration,* at the end of a QUIET
expiration,* at the end of the deepest possible inspiration, and at the end
of the deepest possible expiration.
*NOTE: Quiet inspiration and expiration are difficult to determine.
Measure each several times before obtaining your answer.
2. Examine the lung demonstration model, which consists of a bell jar,
rubber sheeting, two balloons, a rubber stopper, and glass tubing.
Compare each of the parts of the model with the corresponding part of
the human thorax.
3. Pull down on the rubber sheeting. Observe the change in the
balloons.
4. Push up on the rubber sheeting and observe the results.
EXERCISE 2: THE EFFECT OF CARBON
DIOXIDE ON THE RESPIRATORY CENTER
 DISCUSSION:
 Hyperventilation washes much of the carbon dioxide out of
the blood. The increase in the oxygen content of the arterial
blood after hyperventilation is negligible, but the CO2 level
may fall from a normal value of 44mm Hg, to as low as 15
mm Hg. Hyperventilation may result in a feeling of dizziness
because of cerebralanoxia (due to decreased blood pressure,
an increase in pH, or the constriction of cerebral vessels
caused by the diminished CO2 content of the blood).
Procedure
 1. Breathe quietly for one minute and then note how long the breath can be




held after a QUIET inspiration. (Do not inhale additional air.)
2. Place a straw in your mouth, with the other end in a cup of water. After a
quiet inspiration, hold your breath as long as possible. Just before it is necessary
to take a breath, begin to sip water. Continue timing, and determine the total
time elapsed after the original quiet inspiration until it is necessary to take a
breath.
3. Hyperventilate 15 times (breath deeply and rapidly 15 times) and then
determine how long the breath can be held. Do not continue the experiment if
a pronounced feeling of dizziness results.
4. Place a large paper (or plastic) bag over the mouth and nose. Hyperventilate
into the bag 15 times. Note how long the breath can be held after
hyperventilation into the bag. (The bag should contain no air leaks.)
5. Engage in some form of moderate exercise (brisk walking, walking up and
down stairs, etc.). Determine how long the breath can be held immediately
after the cessation of this exercise.