LAB 6 – RESPIRATORY PHYSIOLOGY LAB ACTIVITIES

PROCEED THROUGH THE ACTIVITIES BELOW, EITHER VIA THE DEMO VIDEOS OR BY YOURSELF, DEPENDING ON THE EXPERIMENT. ANSWER THE QUESTIONS AS YOU GO THROUGH THEM.

 

Materials you will need for this lab:

– a tape measure

– a straw

– a mirror or drinking glass

– a thermometer or thermostat

 

PART A: CHEST MEASUREMENTS AND LUNG DEMO MODEL

 

1. Read the following Introduction. Keep in mind this material when answering questions.

 

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.

 

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 and measure in between inspiration and expiration.

– Record your chest measurement here: (1 point)

Circumference (in inches): _________

 

1. Now record your chest measurement at the end of a QUIET inspiration. *NOTE: Quiet inspiration and expiration are difficult to determine. Measure each several times before obtaining your answer. (1 point)

– Record your chest measurement here:

After Quiet Inspiration: ______

 

iii. Now record your chest measurement at the end of a QUIET expiration. *NOTE: Quiet inspiration and expiration are difficult to determine. Measure each several times before obtaining your answer. (1 point)

– Record your chest measurement here:

After Quiet Expiration: ______

 

1. Now record your chest measurement at the end of a forced (deep as possible) inspiration. (1 point)

– Record your chest measurement here:

After Forced Inspiration: _______

1. Now record your chest measurement at the end of a forced (deep as possible) inspiration. (1 point)

– Record your chest measurement here:

After Forced Expiration: _______

 

Answer the following: Do the above results agree with the theoretical results (i.e., the results you would expect to occur)? If so, explain why you think they do. If not, explain why not? (3 points)

 

 

 

 

 

 

 

 

 

 

1. Watch the video of the two demonstrations. 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.
2. Observe the change in the balloons as the instructor pulls the rubber sheeting down.
3. Observe the change in the balloons as the instructor pushes up on the rubber sheeting.

 

Answer the following: What happened when rubber sheeting was lowered and explain why? (3 points)

 

 

 

 

 

 

 

 

Answer the following: What happened when rubber sheeting was raised and explain why? (3 points)

 

 

 

 

 

 

 

PART B: THE EFFECT OF CARBON DIOXIDE ON THE RESPIRATORY CONTROL CENTERS

 

1. Read the following Introduction. Keep in mind this material when answering questions.

The major driver of respiration is the gas Carbon Dioxide. Levels of this gas must be carefully controlled. Hyperventilation, breathing too rapidly, washes much of the carbon dioxide out of the blood. The increase in the oxygen content of the arterial blood after hyperventilation, from taking in more oxygen faster, is negligible, but Carbon Dioxide levels may fall from a normal value of 44mm Hg, to as low as 15mm Hg, dangerously low levels, resulting in a feeling of dizziness because of cerebral anoxia (reduced oxygen levels). This is due to decreased blood pressure, an arterial pH increase, or the constriction of cerebral vessels caused by the diminished CO2 content of the blood).

 

2. Perform the following experiments on yourself, recording the results of each experiment. Note that your results can be skewed if you do not let your breathing return to normal between each test. (1 point each answer)

 

1. BASELINE:

– Breathe quietly for one minute.

– Take in a quiet inhalation.

– Begin a timer.

– Stop the timer when you need to take a breath.

– Record the time you are able to hold your breath after a quiet inspiration. _______s

– Wait until your breathing rate has returned to normal before beginning part ii.

 

 

1. AFTER SIPPING WATER:

– Place a straw in your mouth, with the other end in a cup of water.

– After a quiet inspiration, begin to sip water. Do not breathe between each sip.

– Stop sipping when it is absolutely necessary to take a breath.

– Take a breath, start the timer, and then HOLD your breath.

– Record the time you are able to hold your breath after sipping water and taking one breath. _______s

– Wait until your breathing rate has returned to normal before beginning part iii.

 

 

iii. HYPERVENTILATION:

– Hyperventilate 15 times (breathe deeply AND rapidly).

– Start the timer and hold your breath. Do not continue the experiment if a pronounced feeling of dizziness results.

– Stop the timer when it is necessary to take a breath.

– Record the time you are able to hold your breath after hyperventilating. _______s

– Wait until your breathing rate has returned to normal before beginning part iv.

 

 

1. HYPERVENTILATION INTO A BAG (REBREATHING):

– Place a large paper (or plastic) bag over the mouth and nose.
– Hyperventilate into the bag 15 times.

– Start the timer and hold your breath.

– Stop the timer when it is necessary to take a breath.

– Record the time you can hold your breath after hyperventilation into a bag. _______s

– Wait until your breathing rate has returned to normal before beginning part v.

 

 

1. EXERCISE:

– Engage in some form of moderate exercise (brisk walking, walking up and down stairs).

– Stop exercising and start a timer as you begin to hold your breath.

– Stop the timer when it is necessary to take a breath.

– Record the time you are able to hold your breath after exercise. _________s

 

 

 

PART C: TEMPERATURE AND COMPOSITION OF EXHALED AIR

 

1. Read the following Introduction. Keep in mind this material when answering questions.

The respiratory system modifies air by cleansing, warming and humidifying it. When carbon dioxide combines with water, in the presence of an enzyme called carbonic anhydrase, an acid known as carbonic acid is formed. The equation is: CO₂ + H₂O —> H₂CO₃. 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 exercises using the formulas below to convert between Fahrenheit & Celsius.

 

Celsius = (°F-32)

Fahrenheit = °C + 32

 

2. Perform the following experiments on yourself, with a partner, recording the results of each experiment.

 

 

1. TEMPERATURE OF EXHALED AIR

– Look at a thermometer and determine and record room temperature. If you don’t have a thermometer, use the thermostat in your home (1 point each)

Room Temperature in Degrees Celsius _____________

Room Temperature in Degrees Fahrenheit __________

 

– Hold the thermometer about two to three inches from its end, between the lips about an inch into the mouth. The bulb should not be touching any part of your body.

– Exhale air rapidly over the bulb of the thermometer five times & immediately take a temperature reading, recording that result here. If you do not have a thermometer in your home, place your index finger at the opening of your mouth and exhale onto it. Use the *relative* temperature you feel that you exhaled. Do you think that temperature is warmer than or cooler than your thermostat says? (1 point each answer)

Temperature of Exhaled Air in Degrees Celsius _____________

Temperature of Exhaled Air in Degrees Fahrenheit __________

– Compare the two temperatures and record your observations below.

 

 

 

 

 

 

1. MOISTURE IN EXHALED AIR

– Exhale air on a drinking glass/mirror. What is collecting on the surface of the glass plate/mirror? Try to use proper science terms. Record your answer and observations here: (3 points)

 

 

 

 

 

iii. COMPOSITION OF EXHALED AIR

– Watch the rest of the demonstration video. The instructor will blow through a straw into a solution of Bromothymol blue.

– The Bromothymol blue is a pH indicator. It is blue under alkaline conditions and turns green to yellow as the solution becomes more acidic.

– Record your observations of the change you view, here and answer why it appears to change color. (3 points)

 

 

FINISH YOUR LAB BY ANSWERING THE FOLLOWING POST-LAB QUESTIONS.

1. TYPE YOUR ANSWERS INTO THIS DOCUMENT. NON-TYPED REPORTS WILL NOT BE SCORED.
2. USE COMPLETE AND PROPER SENTENCES FOR ALL ANSWERS EXCEPT LISTS. SLOPPY WORK WILL NOT BE SCORED.
3. PLEASE KEEP THE POINT VALUES WITH THE QUESTIONS, AND THE QUESTIONS WITH YOUR ANSWERS

 

 

1. List the muscles that contract during quiet inspiration (Your lecture recordings give you these exact muscles). 4 points

 

2. List the muscles that contract during forced inspiration (Your lecture recordings give you these exact muscles). 4 points

 

3. List the muscles that contract during forced expiration (Your lecture recordings give you these exact muscles). 4 points

 

4. Why is it that you have not been asked about muscles that contract during quiet expiration? 4 points

 

5. To which structure in the human respiratory system does each of the following structures in the lung demonstration model correspond? 4 points
6. Balloons ____________________ c. Glass Y Tube ____________________
7. Rubber Sheeting _______________ d. Bell Jar _________________________

 

6. STATE and EXPLAIN Boyle’s Law. THEN use it to explain why the balloons expand when the rubber sheeting is lowered. (APPLY the law to inspiration). This is a higher point value question. Your answer should be reflective of that. 12 points

 

THE EFFECT OF CARBON DIOXIDE ON THE RESPIRATORY CONTROL CENTERS

Go back and consider the experiments testing your ability to hold your breath after certain activities. Comparing these activities to your baseline, discuss each situation and whether or not you were able to hold your breath for a shorter time than baseline, or a longer time than baseline. Also include in your answer, why you think your results were the case (NOTE: This section and experiments are based on *Carbon Dioxide* as the major driver of respiration. Your answers should not focus on Oxygen and to receive credit, you must explain carbon dioxide’s role in each situation).

 

BASELINE:

Time you were able to hold your breath after a quiet inspiration. _______s

 

7a. AFTER SIPPING WATER:

Time you were able to hold your breath from a quiet inspiration through the end of sipping water. _______s

Why did this decrease or increase from baseline? 4 points

 

7b. HYPERVENTILATION:

Time you were able to hold your breath after hyperventilating. _______s

Why did this decrease or increase from baseline? 4 points

 

7c. HYPERVENTILATION INTO A BAG (REBREATHING):

Time you were able to hold your breath after hyperventilation into a bag. _______s

Why did this decrease or increase from baseline? 4 points

 

7d. EXERCISE:

Time you were able to hold your breath after exercise. _________s

Why did this decrease or increase from baseline? 4 points

 

8. What is deglutition apnea? To which experiment in the above question does it relate, and EXPLAIN WHY? 6 points

 

9. Why shouldn’t dizziness occur when hyperventilating into a bag as opposed to hyperventilating without it? 8 points

 

TEMPERATURE AND COMPOSITION OF EXHALED AIR

10. From the demonstration video, why did the Bromothymol blue solution change color? EXPLAIN the reaction. 2 points

 

11. Explain why hyperventilation causes an increase in blood pH? (HINT: Reread the Introduction to this section). 6 points