[PhysioEX Chapter 7 exercise 1] PEX-07-01

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Exercise 7: Respiratory System Mechanics: Activity 1: Measuring Respiratory Volumes and Calculating Capacities Lab
Report

Pre-lab Quiz Results
You scored 100% by answering 5 out of 5 questions correctly.

1. Which of the following statements describing the mechanics of breathing is false?
   You correctly answered: d. Ventilation relies exclusively on contracting skeletal muscles.
2. The contraction of which of the following muscles will increase the thoracic cavity volume during inspiration?
   You correctly answered: c. the external intercoatals.
3. At the beginning of inspiration, the
   You correctly answered: b. thoracic cavity volume increases.
4. At the beginning of expiration, the
   You correctly answered: a. pressure in the thoracic cavity increases.
5. A tidal volume refers to the
   You correctly answered: b. amount of air inspired and then expired with each breath under resting conditions.

Experiment Results

Predict Question:
Predict Question: Lung diseases are often classified as obstructive or restrictive. An obstructive disease affects airflow,
and a restrictive disease usually reduces volumes and capacities. Although they are not diagnostic, pulmonary function
tests such as forced expiratory volume (FEV1) can help a clinician determine the difference between obstructive and
restrictive diseases. Specifically, an FEV1 is the forced volume expired in 1 second.

In obstructive diseases such as chronic bronchitis and asthma, airway radius is decreased. Thus, FEV1 will
Your answer : a. decrease proportionately.

Stop & Think Questions:

Which muscles contract during quiet expiration?
You correctly answered: d. None of these muscles contract during quiet expiration.

1. Minute ventilation is the amount of air that flows into and then out of the lungs in a minute. Minute ventilation (ml/min) =
   TV (ml/breath) x BPM (breaths/min).

Using the values from the second recorded measurement, enter the minute ventilation in the field below and then click
Submit to record your answer in the lab report.
You answered: 7500 ml/min

1. A useful way to express FEV1 is as a percentage of the forced vital capacity (FVC). Using the FEV1 and FVC values
   from the data grid, calculate the FEV1 (%) by dividing the FEV1 volume by the FVC volume (in this case, the VC is equal to
   the FVC) and multiply by 100%.

Enter the FEV1 (%) for an airway radius of 5.00 mm in the field below and then click Submit to record your answer in the
lab report.
You answered: 74

1. A useful way to express FEV1 is as a percentage of the forced vital capacity (FVC). Using the FEV1 and FVC values
   from the data grid, calculate the FEV1 (%) by dividing the FEV1 volume by the FVC volume (in this case, the VC is equal to
   the FVC) and multiply by 100%.

Enter the FEV1 (%) for an airway radius of 3.00 mm in the field below and then click Submit to record your answer in the
lab report.
You answered: 70

Experiment Data:
Radius Flow
(L/min)
TV ERV IRV RV VC FEV1 TLC Breath Rate
5.00 7485 499 --- --- --- --- --- --- 15
5.00 7500 500 1200 3091 1200 4791 3541 5991 15
4.50 4920 328 787 2028 1613 3143 2303 4756 15
4.00 3075 205 492 1266 1908 1962 1422 3871 15
3.50 1800 120 288 742 2112 1150 822 3262 15
3.00 975 65 156 401 2244 621 436 2865 15

Post-lab Quiz Results
You scored 100% by answering 5 out of 5 questions correctly.

1. To calculate a person's vital capacity, you need to know the TV, ERV, and
   You correctly answered: c. IRV.
2. Measuring a person's FVC means that you are measuring
   You correctly answered: d. the amount of air that can be expelled when the subject takes the deepest possible inspiration
   and then forcefully expires as completely and rapidly as possible.
3. Measuring a person's FEV1 means that you are measuring
   You correctly answered: b. the amount of the VC that is expired during the first second of the FVC test.
4. For a person suffering an asthma attack, inhaler medications are expected to
   You correctly answered: a. reduce the airway resistance.
5. Which of the following values does not include the ERV?
   You correctly answered: c. TV

Review Sheet Results

1. What would be an example of an everyday respiratory event the ERV simulates?
   Your answer:
   Forced expiration.
2. What additional skeletal muscles are utilized in an ERV activity?
   Your answer:
   Abdominal muscles and the internal intercostal muscles contract.
3. What was the FEV1 (%) at the initial radius of 5.00 mm?
   Your answer:
   73.9%
4. What happened to the FEV1 (%) as the radius of the airways decreased? How well did the results compare with your
   prediction?
   Your answer:
   FEV1 decresed with radius decreasing, as predicted.
5. Explain why the results from the experiment suggest that there is an obstructive, rather than a restrictive, pulmonary
   problem.
   Your answer:
   In obstructive situation, the radius decreases. As the radius decresed, FEV1 decreases.