Lab 11 Respiration worksheet PDF

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BIO 270 Lab 11: Respiration worksheet

score ______ /10

Instructions: Type your answers directly on this document and print out when completed. For question #4b-d and all of #5, use the experimental data provided on Canvas; all other portions of this worksheet should be completed with your own group’s data. NOTE: you should not use anthropomorphic or teleological statements, as described in the Appendix of the EKG background reading, in any of your explanations. Names:

1. Lung volumes and capacities a. Explain why inspiratory flow is faster than expiratory flow at rest. Include in your discussion when muscular effort is required versus passive recoil. (0.5 pt) The simultaneous contraction of the external intercostal muscles and diaphragm causes air to flow into the lungs during inspiration. This contraction increases the dimensions of the thoracic cavity by increasing the volume of the lungs and decreasing the pressure inside the lungs. The decrease in pressure inside the lungs causes air to move from an area of high pressure (the atmosphere) to areas of low pressure (the lungs). Expiration occurs when the pressure inside the lungs becomes greater than the atmospheric pressure. The relaxation of the external intercostal muscles and diaphragm helps to facilitate the passive movement of air out of the lungs, which decreases the volume of the lungs and increases the pressure to expel the air. The passive recoil takes longer than the muscle contraction, and since muscles take less time to contract, inspiratory flow is faster than expiratory flow at rest. b. Explain why residual volume cannot be determined by ordinary spirometry. (0.25 pt) Residual volume is the air left in the lungs after the expiratory reserve volume has been expired. Spirometry measures the amount of air that is inhaled and exhaled. Since the residual volume is a measure of how much air is remaining in the lungs after exhalation and not being exhaled, the spirometry is unable to make this measurement. 2. Pulmonary function tests a. What is the spirogram's red line measuring? Units? (0.25 pt) Flow Rate (L/min) b. What is the spirogram's blue line measuring? Units? (0.25 pt) Volume (L) 3. Simulated airway obstruction a. Complete Table 1 by recording the values displayed on lab tutor. (0.5 pt) Table 1. The effect of obstruction on select airflow rates and lung volumes. Measurement Peak expiratory flow (PEF) Vital capacity (VC) Forced expired volume in 1 sec (FEV1) % FVC expired in 1 sec (FEV1/VC)

Units Unobstructed L/min 82 L 3.02 L 0.84 % 28%

Obstructed 59 2.97 0.19 7%

b. Which values were affected by simulated airway obstruction? Why? Should any have remained the same? Why? (0.5 pt)

All the values except the vital capacity should have been affected by the airway obstruction. This is because an obstruction in the airway makes it harder for an individual to exhale. An obstruction does not affect the amount of air that the lungs can hold however, so the vital capacity should have stayed the same. c. Describe the physiological significance of the FEV1/VC ratio. How can this ratio expose an underlying disease? (0.75 pt) The FEV1/VC ratio is a measurement of forced expiration in one second. It’s clinically used to determine the health of lungs, with a ratio of about 80% being normal. If the ratio is less than 50%, then it suggests the individual has obstructive lung disease, and if the ratio is greater than 90%, then it suggests the individual has restricted air movement (i.e. tumors lining the walls of the lungs). 4. Effect of Exercise Note: Enter the pre- and post-exercise TV, IRV, ERV and VC for your subject on the instructor’s computer. a. Complete Table 2 by recording the values displayed on lab tutor. (0.5 pt) Table 2. The effect of exercise on respiratory rate and lung volumes and capacities. Pre-exercise

Post-exercise

breaths/min

14

18

L L/min L L L

0.68 9.52 1.00 1.16 1.31

1.18 21.24 1.89 2.96 1.31

L L L L L

1.68 1.84 2.84 2.47 4.16

3.07 4.14 6.03 4.27 7.34

RATES Respiratory rate (RR) VOLUMES Tidal volume (TV) Expired minute volume (VE) TVxRR Inspiratory reserve volume (IRV) Expiratory reserve volume (ERV) Residual volume (RV) CAPACITIES Inspiratory capacity (IC) TV+IRV Expiratory capacity (EC) TV+ERV Vital capacity (VC) IRV+TV+ERV Function residual capacity (FRC) ERV+RV Total lung capacity (TLC) VC+RV

Note: Use the data posted on Canvas to complete b & c. b. Construct Figure 1 describing the effect of exercise on TV, IRV, ERV and VC. (0.5 pt)

Figure 1. The effect of exercise on TV, IRV, ERV, and VC. c. Perform four t-tests to determine if there is a difference in the TV, IRV, ERV, and VC before and after exercise. Enter the p-values in Table 3 and indicate which values are significant. (0.5 pt) Table 3. p-values representing the differences in lung volumes of subjects before and after exercise. TV p=

2.99E-14*

IRV

ERV

VC

7.11E-0-4*

4.04E-06*

6.70E-01

d. Explain any significant differences in Table 3 in good physiologic terms. (0.75 pt) Exercise increases metabolic activity, so more carbon dioxide is produced from the muscles that are working. The carbon dioxide is transported by the blood, which then goes to the brain, where it crosses the blood brain barrier. Carbon dioxide then mixes with water, creating carbonic acid. In response to the carbonic acid, the chemoreceptors in the brain signal the activation of the sympathetic nervous system which increases the rate and volumes of breaths. As the breaths get deeper and faster, the tidal volume increases. Vital capacity is made up of the tidal volume, inspiratory respiratory volume, and expiratory respiratory volume. Since vital capacity is not significant because the amount of air entering and exiting the lungs remain constant, the inspiratory respiratory volume and expiratory respiratory volume must decrease.

5. Breath-holding

Note: Enter the breath-hold time for each bout of hyperventilation, as well as the post-exercise breathhold time on the instructor’s computer. Note: Use the data posted on Canvas to complete a, d & e. a. Construct Figure 2 that describes the effect of hyperventilation duration on breath-hold time. (0.5 pt)

Figure 2. The effect of hyperventilation time on breath-hold time. b. Provide a physiologic explanation of your figure. (1 pt) Hyperventilation is fast paced breathing that decreases the amount of carbon dioxide in the blood. Decreased CO2 levels allow an individual to hold their breath for longer since the central chemoreceptors do not sense a rise in carbonic acid build up. c. What would you expect to be the breath-hold duration of an individual who exercised briefly (~2-4 minutes) then engaged in a bout of hyperventilation? Why? (0.75 pt) The breath-hold duration of an individual who exercised briefly then engaged in a bout of hyperventilation could be somewhere in between the duration of an individual who only exercised and an individual who only hyperventilated.

d. Construct Figure 3 that describes the effect of exercise on breath-hold time. (0.5 pt)

Figure 3. The effect of exercise on breath-hold time. e. Perform a t-test to determine if there is a difference in breath-hold time after exercise. Report your pvalue. Include a conclusion based on your statistical data. Additionally, provide a physiological explanation for the observed effect of exercise. (2 pt) p-Value: 3.15E-22 We can conclude that exercise decreases breath-hold time. Exercise increases the metabolic rate of muscles that use oxygen to produce ATP which then releases carbon dioxide as a byproduct. Central chemoreceptors in the brain detect the increase in carbon dioxide in the blood, which increases the breathing rate....