PhysioEx Exercise 7 Activity 1

In this experiment we will measure respiratory volumes of simulated lungs, and observe how decreasing the airway radius affects these volumes. The lungs are suspended in a bell jar with a movable rubber diafragm, which allows to regulate the volume of air inside the lungs. The atmospheric air can move into the bell jar through the tube with adjustable airway radius. We will gather the data from the tracing on the oscilloscope, which shows the lungs volume versus time graph.

Note that the airway radius is set to 5.00 mm. Select Start to initiate the normal breathing patterns and establish the baseline (or normal) respiratory volumes. Observe the spirogram that develops on the oscilloscope and note that the simulated lungs breathe (ventilate) a tidal volume as a result of the contraction and relaxation of the diaphragm.

Select Record Data to display your results in the grid.

Select Clear Tracings to clear the spirogram on the oscilloscope.

You will now complete the measurement of respiratory volumes and determine the respiratory capacities.

First, select Start to initiate the normal breathing pattern. After 10 seconds (as measured on the oscilloscope), select ERV. Wait another 10 seconds (on the oscilloscope) and then select FVC to complete the measurement of respiratory volumes.

When you select ERV, the program will simulate forced expiration using the contraction of the internal intercostal muscles and abdominal-wall muscles.

When you select FVC, the lungs will first inspire maximally and then expire fully to demonstrate forced vital capacity.

Note that, in addition to the tidal volume, the expiratory reserve volume, inspiratory reserve volume, and residual volume were measured. The vital capacity and total lung capacity were calculated from those volumes.

Select Record Data to display your results in the grid.

Stop & Think Question

Which muscles contract during quiet expiration?

external intercostal muscles and the diaphragm

abdominal-wall muscles and internal intercostal muscles

external and internal intercostal muscles

none of these muscles contract during quiet expiration

Incorrect

The correct answer is:

none of these muscles contract during quiet expiration

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 select Submit Data to record your answer in the lab report.

ml/min

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 (F E V subscript 1 baselineFEV₁) can help a clinician determine the difference between obstructive and restrictive diseases. Specifically, an F E V subscript 1 baselineFEV₁ is the forced volume expired in 1 second.

In obstructive diseases such as chronic bronchitis and asthma, airway radius is decreased. Thus, F E V subscript 1 baselineFEV₁ will

decrease proportionately.

increase proportionately.

not change significantly.

You will now explore what effect changing the airway radius has on pulmonary function. Decrease the airway radius to 4.50 mm by selecting the - button beneath the airway radius display.

Select Start to initiate the normal breathing pattern. After 10 seconds (as measured on the oscilloscope), select ERV. Wait another 10 seconds (on the oscilloscope) and then select FVC. The F E V subscript 1 baseline will appear in the F E V subscript 1 baseline display beneath the oscilloscope.

Select Record Data to display your results in the grid.

You will now gradually decrease the airway radius.

Decrease the airway radius by 0.50 mm by selecting the - button beneath the airway radius display.
Select Start to initiate the normal breathing pattern. After 10 seconds (as measured on the oscilloscope), select ERV. Wait another 10 seconds (on the oscilloscope) and then select FVC. The F E V subscript 1 baseline will appear in the F E V subscript 1 baseline display beneath the oscilloscope.
Select Record Data to display your results in the grid.

Repeat this step until you have tested an airway radius of 3.00 mm.

A useful way to express F E V subscript 1 baselineFEV₁ is as a percentage of the forced vital capacity (FVC). Using the F E V subscript 1 baselineFEV₁ and FVC values from the data grid, calculate the F E V subscript 1 baselineFEV₁ (%) by dividing the F E V subscript 1 baselineFEV₁ volume by the FVC volume (in this case, the VC is equal to the FVC) and multiply by 100%.

Enter the F E V subscript 1 baselineFEV₁ (%) for an airway radius of 5.00 mm in the field below and then select Submit Data to record your answer in the lab report.

A useful way to express F E V subscript 1 baselineFEV₁ is as a percentage of the forced vital capacity (FVC). Using the F E V subscript 1 baselineFEV₁ and FVC values from the data grid, calculate the F E V subscript 1 baselineFEV₁ (%) by dividing the F E V subscript 1 baselineFEV₁ volume by the FVC volume (in this case, the VC is equal to the FVC) and multiply by 100%.

Enter the F E V subscript 1 baselineFEV₁ (%) for an airway radius of 3.00 mm in the field below and then select Submit Data to record your answer in the lab report.

Congratulations! You have completed this Experiment.

Select Submit to record your results in the Lab Report and proceed to the Post-lab Quiz.

Click Submit only when you complete the experiment to submit results to the lab report.Click Undo to repeat the last step in the Experiment.Click Reset to start the Experiment from the beginning. If you Reset the Experiment, your data will be lost.

Current state of the experiment

The airway radius is set to 5 millimeters.

Press to initiate the normal breathing pattern.

Tidal Vol.Tidal volumeTidal Vol.Tidal volume

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Exp. Res. Vol.Expiration reserve volumeExp. Res. Vol.Expiration reserve volume

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Insp. Res. Vol.Inspiration reserve volumeInsp. Res. Vol.Inspiration reserve volume

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Res. Vol.Residual volumeRes. Vol.Residual volume

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Vital Cap.Vital capacityVital Cap.Vital capacity

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F E V subscript 1 baselineFEV₁F E V subscript 1 baselineFEV₁

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Total Lung Cap.Total lung capacityTotal Lung Cap.Total lung capacity

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Breath Rate (BPM)Breath Rate. B P M Breath Rate (BPM)Breath Rate. B P M

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Air Flow (liters/min)Air Flow (liters/min)

0.00

Airway Radius (millimeters)Airway Radius (mm)

5.00

Radius (millimeters)Radius (mm)Flow (milliliters per minute)Flow (ml/min)TV (milliliters)TV (ml)ERV (milliliters)ERV (ml)IRV (milliliters)IRV (ml)RV (milliliters)RV (ml)VC (milliliters)VC (ml)F E V subscript 1 baseline (milliliters)FEV₁ (ml)TLC (milliliters)TLC (ml)B P MBPM

Measuring Respiratory Volumes and Calculating Capacities

Objectives

Introduction

Pre-lab Quiz

Experiment

Post-lab Quiz

Review Sheet

Lab Report

Stop & Think Question

Predict Question