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# Respiratory System Mechanics

1.) When you forcefully exhale your entire expiratory reserve volume, any air remaining in your lungs is called the residual volume (RV). Why is it impossible to further exhale the RV (that is, where is this air volume trapped, and why is it trapped?)

This “dead space” of air needs to stay in your lungs constantly; otherwise the lung will completely deflate. If the lung has every bit of air sucked out of it, it will collapse and need to be re-inflated.

2.) How do you measure a person’s RV in a laboratory?

By the air remaining in the lung

3.) Draw a spirogram that depicts a person’s volumes and capacities before and during a significant cough.

The following questions refer to Activity 1: Measuring Respiratory Volumes and Calculating Capacitates

1.) What would be an example of an everyday respiratory event the ERV button Stimulates? forced expiration

2.) What additional skeletal muscles are utilized in an ERV activity? abdominal-wall muscles and the internal intercostal muscles contract

3.) What was the FEV1 (%) at the initial radius of 5.00 mm?
73.9%

4.) What happened to the FEV1 (%) as the radius of the airways decreased? How well did the results compare with your prediction?

FEV1 (%) decreased proportionally with the radius

5.) Explain why the results from the experiment suggest that there is an obstructive, rather than a restrictive, pulmonary problem.

The FEV1 (%) decreased proportionally as the radius decreased, characteristic of an obstructive pulmonary problem

Activity 2 Comparative Spriometry

Chart 2: Spirometery Results
Patient Type
TV (ml)
ERV
(ml)
IRV
(ml)
RV (ml)
FVC (ml)
TLC
(ml)
FEV1
(ml)
FEV1 (%)
Normal

500
1500
3000
1000
5000
6000
4000
80%
Emphysema

500
750
2000
2750
3250
6000
1625
50%
Acute asthma attack
300
750
2700
2250
3750
6000
1500
40%
Plus inhaler
500
1500
2800
1200
4800
6000
3840
80%
Moderate exercise
1875
1125
2000
1000
ND
6000
ND
ND
Heavy exercise
3650
750
600
1000
ND
6000
ND
ND

1.) Why is residual volume (RV) above normal in a patient with emphysema?

The lungs empty slower than normal.

2.) Why did the asthmatic patient’s inhaler medication fail to return all volumes and capacities to normal values right away?

The smooth muscle in the bronchioles didn’t return to normal plus mucus still blocks the airway.

3.) Looking at the spirograms generated in this activity, state an easy way to determine whether a person’s exercising effort is moderate or heavy.

The more rapid the lines the more heavier the exercise.

The following questions refer to Activity 2 Comparative Spirometry

1.) What lung values changed (From those of the normal patient) in the spirogram when the patient with emphysema was selected? Why did these values change as they did? How well did the results compare with your prediction?

ERV, IRV, RV, FVC, FEV, and FEV1 (%) all changed; these are due to the loss of elastic recoil

2.) Which of these two parameters changed more for the patient with emphysema, the FVC or the FEV1? FEV1 decreased significantly more

3.) What lung values changed (from those of the normal patient) in the spirogram when the patient experiencing an acute asthma attack was selected? Why did these values change as they did? How well did the results compare with your prediction?

TV, ERV, IRV, RV, FVC, FEV1, and FEV1 (%) all changed; due to restriction of the airways

4.) How is having an acute asthma attack similar to having emphysema? How is it different?

Similar because obstructive diseases characterized by increased airway resistance; Different because more difficult to exhale with emphysema that with asthma

5.) Describe the effect that the inhaler medication had on the asthmatic patient. Did all the spirogram values return to “normal”? Why do you think some values did not return all the way to normal? How well did the results compare with your prediction?

Returned to normal were TV, ERV, FEV1 (%); smooth muscles in the bronchioles didn’t return to normal blue mucus still blocks the airway

6.) How much of an increase in FEV1 do you think is required to be considered significantly improved by the medication? 10-15% improvement

7.) With moderate aerobic exercise, which changed more from normal breathing, the ERV or the IRV? How well did the results compare with your prediction?

IRV changed more with moderate activity

8.) Compare the breathing rates during normal breathing, moderate exercise,
and heavy exercise. TV increased over normal breathing with both moderate and heavy exercise.

Activity 3. Effect of Surfactant and Intrapleural Pressure on Respiration

Chart 3: Effect of Surfactant and Intrapleural Pressure on Respiration Surfactant
Intrapleural pressure left (atm)
Intrapleural pressure right (atm)
Airflow left
(ml.min)
Airflow right
(ml/min)
Total Airflow
(ml/min)
0
-4
-4
49.69
49.69
99.38
2
-4
-4
69.56
69.56
139.13
4
-4
-4
89.44
89.44
178.88
0
-4
-4
49.64
49.64
99.38
0
0.00
-4
0.00
49.64
49.69
0
0.00
-4
0.00
49.69
49.69
0
-4
-4
49.69
49.69
99.38

1.) Why is normal quiet breathing so difficult for premature infants?

They don’t have much surfactant.

2.) Why does a pneumothorax frequently lad to atelectasis?

If the lungs are broken down mechanically, then the chances of developing increased.

The following questions refer to Activity 3: Effect of Surfactant and Intrapleural Pressure on Respiration

1.) What effect does the addition of surfactant have on the airflow? How well did the results compare with your prediction?

AIrflow increases because resistance is reduced

2.) Why does surfactant affect airflow in this manner?

It decreases surface tension in the alveoli making it easier for the alveoli to increase surface area for gas exchange.

3.) What effect did opening the valve on the left lung? Why does this happen?

The lung collapses because the pressure in the pleural cavity was less than the intrapulmonary pressure; air flows from the lungs, causing it to collapse

4.) What effect on the collapsed lung in the left side of the glass bell jar did you observe when you closed the valve? How well did the results compare with your prediction?

It caused the lung to collapse because the pressure in the pleural cavity is less than the intrapulmonary pressure. Air flows from the lungs causing the collapse of the lung.

5.) What emergency medical condition does opening the left valve simulate?

A collapsed lung (pneumothorax) is a buildup of air in the space between the lung and the chest wall (pleural space). As the amount of air in this space increases, the pressure against the lung causes the lung to collapse

6.) In the last part of the activity, you clicked the Reset button to draw the air out of the intrapleural space and return the lung to its normal resting condition. What emergency procedure would be used to achieve this result if these were the lungs in a living person?

A chest by insertion of tube to draw air out of pleural cavity and restore the pressure gradient

7.) What do you think would happen when the valve is opened if the two lungs were in a single large cavity rather than separate cavities?

If both lung were in a single large cavity rather than separate cavity when valve was open the entire lung will collapse and there will be no extra lung to breath with and death would occur much sooner.