Bio13A Lab Manual

Biology 13A Lab #12: The Respiratory System Lab #12 Table of Contents: • Expected Learning Outcomes . . • Introduction . . . . • Activity 1: Structures of the Respiratory • Activity 2: Measuring Respiration . • Activity 3: Film: “Deadly Ascent” .

Expected Learning Outcomes At the end of this lab, you will be able to • locate the major gross structures of the respiratory system on the human torso model; • use a computer and physiological data collection device (Vernier) to monitor the respiratory rate of an individual; • determine the effect of increased carbon dioxide on breathing rate and depth; and • explore the physiological effects of high altitude.

. . . . System . . . .

94 95 96 96 100

Figure 12.1: Lungs

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Bio13A Lab Manual Introduction The organs of the respiratory system include the nose, nasal cavity, sinuses, pharynx, larynx, trachea, respiratory tree, and lungs. They function to transport air to the air sacs of the lungs (the alveoli) where gas exchange occurs. The process of transporting and exchanging gases between the atmosphere and the body cells is respiration. The process of taking in air is known as inspiration, while the process of blowing out air is called expiration. A respiratory cycle consists of one inspiration and one expiration. The point of respiration is to allow you to obtain oxygen, eliminate carbon dioxide, and regulate the blood’s pH level. Respiration rate (breaths per minute) and depth (volume of air

inhaled and exhaled with each breath) varies due to changes in blood chemistry that are monitored by the brain. For example, when you exercise, demand for oxygen increases because the cells require more ATP. In turn, more carbon dioxide is produced by cells and diffuses to the blood. The rise in carbon dioxide leads to a decrease in pH, causing the blood to be more acidic. The brain is especially sensitive to pH levels; as pH levels in the blood fall, the brain stimulates more rapid breathing and deeper breathing. The effect is to draw more air into the lungs, to transport more oxygen to the cells, and to lower pH and CO2 levels.

Check Your Understanding: Answer the following questions based on your reading of the introduction. 1. Where does gas exchange occur? 2. What is one complete respiratory cycle? Define breathing rate and breathing depth. 3. What happens to breathing rate and depth during exercise? What are the changes in blood chemistry that lead to the observed changes during exercise?

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Bio13A Lab Manual Activity 1: Structures of the Respiratory System Locate the following structures on the model of the human torso and the real skull. • • • •

• • • • • • • • • • • • • • • • • •

Nostrils (external nares) Nasal cavity Nasal septum Nasal conchae • Superior Nasal concha • Middle Nasal Concha • Inferior Nasal Concha Palatine Tonsils Pharyngeal Tonsils (Adenoids) Sinuses Frontal Sinus Maxillary Sinus Pharynx Larynx Vocal Cords Thyroid Cartilage (Adam’s Apple) Cricoid Cartilage Epiglottis Glottis Trachea Bronchi Lung Lobes Visceral Pleura Parietal Pleura

1. Breathing can also be called __________________. 2. When the diaphragm contracts, the size of the thoracic cavity __________________. Activity 2: Measuring Respiration The rate at which your body performs a respiratory cycle is dependent upon levels of oxygen and carbon dioxide in your blood. You will monitor the respiratory patterns of one member of your group under different conditions. A respiration belt will be strapped around the test subject and connected to a computer-interfaced gas pressure sensor. Each respiratory cycle will be recorded by the computer, allowing you to calculate a respiratory rate for comparison at different conditions.

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Bio13A Lab Manual PROCEDURE 1. Prepare the computer for data collection by opening the Experiment 26 folder from the Biology with Computers folder of Logger Pro. Then open the experiment file that matches the probe you are using. There are two graphs displayed and two Meter windows. The top graph’s vertical axis has pressure scaled from 96 to 110 kPa. The horizontal axis has time scaled from 0 to 180 seconds. The data rate is set to take five samples per second. The Meter window to the right displays live pressure readings from the sensor. The lower graph’s vertical axis has respiration rate scaled from 0 to 20 breaths/minute. The horizontal axis has time scaled from 0 to 180 seconds. The Meter window to the right displays the calculated respiration rate when data are being collected. (Note: kPa is the symbol for kilopascals (1000 Pa = 1 kPa). A pascal is a measurement of force per unit area.) Figure 12.2 2. If your Gas Pressure Sensor has a blue plastic valve on it, place the valve in the position shown in Figure 12.2.

Connect tubing here

3. Select one member of the group as the test subject. Wrap the Respiration Monitor Belt snugly around the test subject’s chest. Press the Velcro strips together at the back. Position the belt on the test subject so that the belt’s air bladder is resting over the base of the rib cage and in alignment with the elbows as shown in Figure 12.3.

Figure 12.3 4. Attach the Respiration Monitor Belt to the Gas Pressure Sensor. There are two rubber tubes connected to the bladder. One tube has a white Luer-lock connector at the end and the other tube has a bulb pump attached. Connect the Luer-lock connector to the stem on the Gas Pressure Sensor with a gentle half turn. 5. Have the test subject sit upright in a chair. Close the shut-off screw of the bulb pump by turning it clockwise as far as it will go. Pump air into the bladder by squeezing on the bulb pump. Fill the bladder as full as possible without being uncomfortable.

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Bio13A Lab Manual 6. The pressure reading displayed in the Meter window should increase about 6 kPa above the initial pressure reading (e.g., at sea level, the pressure would increase from about 100 to 106 kPa). At this pressure, the belt and bladder should press firmly against the test subject’s diaphragm. Pressures will vary, depending upon how tightly the belt was initially wrapped around the test subject. 7. As the test subject breathes in and out normally, the displayed pressure alternately increases and decreases over a range of about 2 – 3 kPa. If the range is less than 1 kPa, it may be necessary to pump more air into the bladder. Note: If you still do not have an adequate range, you may need to tighten the belt. Part I Holding of Breath 8. Instruct the test subject to breathe normally. Start collecting data by clicking Collect . When data has been collected for 60 seconds, have the test subject hold his or her breath for 30 to 45 seconds. The test subject should breathe normally for the remainder of the data collection once breath has been released. 9. Examine the respiration rates recorded in the bottom graph by clicking the Examine button, . As you move the mouse pointer from point to point on the graph the data values are displayed in the examine window. Determine the respiration rate before and after the test subject’s breath was held and record the values in Table 12.1. Part II Rebreathing of Air 10. Prepare the computer for data collection by opening the Experiment 26B folder from the Biology with Computers folder of Logger Pro. Then open the experiment file that matches the probe you are using. The vertical axis has pressure scaled from 98 to 112 kPa. The horizontal axis has time scaled from 0 to 300 seconds. The data rate is set to take five samples per second. The Meter window to the right displays live pressure readings from the sensor. 11. Place a small paper bag into a plastic produce bag. Have the test subject cover his or her mouth with the bags, tight enough to create an air-tight seal. The test subject should breathe normally into the bags throughout the course of the data collection process. 12. Click Collect to begin data collection. Again, the test subject should be sitting and facing away from the computer screen. Collect respiration data for the full 300 seconds while breathing into the sack. Important: Anyone prone to dizziness or nausea should not be tested in this section of the experiment. If the test subject experiences dizziness, nausea, or a headache during data collection, testing should be stopped immediately. 13. Once you have finished collecting data in Step 12, calculate the maximum height of the respiration waveforms for the intervals of 0 to 30 seconds, 120 to 150 seconds, and 240 to 270 seconds: a. Move the mouse pointer to the beginning of the section you are examining. Hold down the mouse button. Drag the pointer to the end of the section and release the mouse button. b. Click the Statistics button, , to determine the statistics for the selected data. c. Subtract the minimum pressure value from the maximum value (in kPa). d. Record this value for each section as the wave amplitude in Table 2. 98

Bio13A Lab Manual DATA Table 12.1 Holding of Breath Before holding breath

After holding breath

_______ breaths / minute

_______ breaths / minute

Table 2 Rebreathing of Air: Amplitudes of Respiration Waves 0 to 30 seconds

120 to 150 seconds

240 to 270 seconds

________ kPa

________ kPa

________ kPa

QUESTIONS 1. Did the respiratory rate of the test subject change after holding his or her breath? If so, describe how it changed.

2. What is different about the size (amplitude) or shape (frequency) of the respiratory waveforms following the release of the test subject’s breath? Explain.

3. What would be the significance of an increase in the amplitude and frequency of the waveform while the test subject was breathing into the bag?

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Bio13A Lab Manual 4. How did the respiratory waveforms change while the test subject was breathing into the bag? How would you interpret this result?

5. Explain how you think an increase in carbon dioxide in the blood affects your breathing. What is the mechanism?

This lab is a modified version of a lab from University of Pittsburgh’s Science in Motion program for science education.

Activity 3: Film: Deadly Ascent High altitude poses physiological challenges. As one ascends higher, the air pressure lessens and the amount of oxygen decreases. Humans are not adapted to conditions of low levels of oxygen or extreme cold. In this film, a team is followed on its climb of Denali (also known as Mt. McKinley) and the effects of altitude and cold temperatures are observed. Background: Climbers who ascend Denali (Mt. McKinley) can experience health problems in response to extreme conditions—high altitude, low atmospheric pressure, and severe cold. The mountain is 6,194 meters from its base to its summit. Most humans are adapted to living on earth's surface where air pressure is about 14.7 pounds per square inch. At high elevations, because there is less oxygen in a given amount of air, humans who are not acclimated to the environment experience hypoxia, or oxygen deprivation, and they experience health complications such as hypothermia, frostbite, and sometimes gangrene due to intense wind and cold. This chart shows some air pressures at different elevations: Barometric Pressure (mm Hg)

Barometric Pressure* (in Atmospheres)

0 (Sea Level)

760

1

3000 feet

684

0.9

10,000

532

0.7

18,000 (5,600m)

380

0.5

23,000 (7,200 m)

304

0.4

30,000 (9,400 m)

228

0.3

Altitude

(in feet)

From Darwish, A. 2003. Aerospace Medicine: Part 1. The Internet Journal of Pulmonary Medicine. Volume 3 Number 2.