Respiratory Volumes
Activity 2: Measuring Normal Respiratory Volumes
1. Minute respiratory volume: ml
2. Judging from the trace you generated, inspiration took place over how many seconds?
3. Expiration took place over how many seconds?
4. Does the duration of inspiration or expiration vary during ERV or FVC?
Activity 3: Effect of Restricted Air Flow on Respiratory Volumes
1. How does this set of data compare to the data you recorded for Activity 2?
2. Is the respiratory system functioning better or worse than it did in the previous activity? Explain why.
3. What is the effect of reducing the radius of the air flow tube on respiratory volumes?
4. What does the air flow tube simulate in the human body?
5. What could be some possible causes of reduction in air flow to the lungs?
Factors Affecting Respiration
Activity 4: Effect of Surfactant on Respiratory Volumes
1. When surfactant is added, what happens to the tidal volume? FEV1 percentage decreases as the radius of the airway is decreased.
2. As a result of the tidal volume change, what happens to the flow into each lung and total air flow? Airflow increases when surfactant is applied because the resistance to lung inflation has been reduced.
3. Why does this happen?
Activity 5: Effect of Thoracic Cavity Puncture
1. What happened to the left lung when you clicked on the valve button?
2. Why?
3. What has happened to the “Total Flow” rate?
4. What is the pressure in the left lung?
5. Has the pressure in the right lung been affected?
6. If there was nothing separating the left lung from the right lung, what would have happened when you opened the valve for the left lung? Why?
7. Now click the valve for the left lung again, closing it. What happens? Why?
8. Describe the relationship required between intrathoracic pressure and atmospheric pressure in order to draw air into the lungs.
9. Design your own experiment for testing the effect of opening the valve of the right lung. Was there any difference from the effect of opening the valve of the left lung?
Variations in Breathing
Activity 6: Rapid Breathing
1. What happens to the PCO2 level during rapid breathing? PCO2 levels decrease during rapid breathing.
2. Why? Because more CO2 was removed from the blood than normal.
Activity 7: Rebreathing
1. What happens to the PCO2 level during rebreathing? It increased.
2. Why? The air that was inhaled had increased amounts of exhaled CO2.
3. Did the total flow change? Yes
4. Why? Increased pump rate
5. How does the rebreathing trace compare to your baseline trace? The depth and rate of respirations increased during rebreathing.
6. Why? Increased CO2 in the blood causing stimulating of the respiratory centers in the brain stem.
Activity 8: Breath Holding
1. What happens to the PCO2 level during breath holding? PCO2 increased dramatically during breath holding.
2. Why? Because CO2 cannot be released by cells undergoing cellular respiration.
3. What change was seen when you returned to “Normal Breathing”? The rate and depth of breathing increased slightly for a brief period when normal breath-ing resumed to allow PCO2 rates to decrease to the normal range.
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