1. Lab 8 – Respiratory System (Part 2 – Physiology)
Dr. Kim Wilson

2. Textbook Reference – Exercise 37A
Pg. 549
Spirometry video

3. 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.

4. 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.

5. 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

6. 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).

7. 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)

8. Other Formulas Tidal Volume (TV) Expiratory Reserve Volume (ERV):
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

9. 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.

10. 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.

11. 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

12. 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.

13. 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.

14. 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.

15. 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).

16. 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.