Respiratory Physiology Practice Questions

1. Alveolar surfactant acts to increase pulmonary

Surface tension.

Compliance.

Airway resistance.

Alveolar surfactant is a substance produced by the lungs that helps to reduce surface tension within the alveoli. By reducing surface tension, alveolar surfactant prevents the collapse of the alveoli during expiration, allowing for easier and more efficient lung expansion and contraction. This ultimately increases pulmonary compliance, which refers to the ability of the lungs to stretch and expand. Therefore, the correct answer is compliance.

Explanation

Alveolar surfactant is a substance produced by the lungs that helps to reduce surface tension within the alveoli. By reducing surface tension, alveolar surfactant prevents the collapse of the alveoli during expiration, allowing for easier and more efficient lung expansion and contraction. This ultimately increases pulmonary compliance, which refers to the ability of the lungs to stretch and expand. Therefore, the correct answer is compliance.

2.

Respiratory Ventilation	Predicted	Measured	Measure after bronchodilator
Vital Capacity	3.3 L	2.3 L	2.4 L
Residual Volume	0.8 L	0.6 L	0.6 L
Total Lung Capacity	4.1 L	2.9 L	3.0 L
FEV-1	2.6 L	1.9 L	2.0 L
FEV-1 / FVC	> 80%	83%	83%

The following measurements were taken on a 23 year old female with a recent history of dyspnea and cyanosis on exertion. This patient has:

A restrictive disease

An obstructive disease.

A combined obstructive/restrictive disease

The patient has a restrictive disease because the measured values for vital capacity, residual volume, total lung capacity, and FEV-1 are all significantly lower than the predicted values. In a restrictive disease, the lungs are unable to fully expand, resulting in reduced lung volumes and capacities. This is supported by the low measured values for vital capacity, residual volume, and total lung capacity. The FEV-1/FVC ratio being greater than 80% indicates that there is no significant airflow obstruction, further supporting the diagnosis of a restrictive disease.

Explanation

The patient has a restrictive disease because the measured values for vital capacity, residual volume, total lung capacity, and FEV-1 are all significantly lower than the predicted values. In a restrictive disease, the lungs are unable to fully expand, resulting in reduced lung volumes and capacities. This is supported by the low measured values for vital capacity, residual volume, and total lung capacity. The FEV-1/FVC ratio being greater than 80% indicates that there is no significant airflow obstruction, further supporting the diagnosis of a restrictive disease.

3. Contraction of the abdominal muscles is important in

Normal (quiet) inspiration.

Forced (maximum) inspiration

Normal (quiet) expiration.

Forced (maximum) expiration.

None of the above.

During forced (maximum) expiration, the contraction of the abdominal muscles is important. This contraction helps to increase the pressure in the thoracic cavity, which in turn helps to push air out of the lungs more forcefully. This is necessary during activities such as coughing, sneezing, or exercising when a larger volume of air needs to be expelled from the lungs quickly. In normal (quiet) expiration, the abdominal muscles are not actively contracted. Therefore, the correct answer is forced (maximum) expiration.

Explanation

During forced (maximum) expiration, the contraction of the abdominal muscles is important. This contraction helps to increase the pressure in the thoracic cavity, which in turn helps to push air out of the lungs more forcefully. This is necessary during activities such as coughing, sneezing, or exercising when a larger volume of air needs to be expelled from the lungs quickly. In normal (quiet) expiration, the abdominal muscles are not actively contracted. Therefore, the correct answer is forced (maximum) expiration.

4. An elderly man tripped and fell down a flight of steps, breaking a rib which caused a pneumothorax. If you were to measure the circumference of this man's chest, you would expect it to be:

Larger than normal

Normal

Smaller than normal.

Cannot predict without additional information.

When a person breaks a rib, it can lead to a condition called pneumothorax, where air accumulates in the space between the lung and the chest wall. This can cause the affected lung to collapse partially or completely. As a result, the chest cavity may expand to accommodate the extra air, causing the circumference of the chest to be larger than normal.

Explanation

When a person breaks a rib, it can lead to a condition called pneumothorax, where air accumulates in the space between the lung and the chest wall. This can cause the affected lung to collapse partially or completely. As a result, the chest cavity may expand to accommodate the extra air, causing the circumference of the chest to be larger than normal.

5. Residual volume of 2.5 liters is:

Above normal

Below normal

Within the normal range

normal value for a Man is 1.2 and woman is 1.1

Explanation

normal value for a Man is 1.2 and woman is 1.1

6. Spirometry can be used to measure:

FRC.

RV

TLC

FVC

Spirometry is a pulmonary function test that measures the amount and speed of air that can be inhaled and exhaled. FVC (Forced Vital Capacity) is one of the parameters measured during spirometry. It represents the maximum amount of air a person can forcefully exhale after taking a deep breath. FVC is an important measurement as it provides information about lung function and can help diagnose and monitor respiratory conditions such as asthma, chronic obstructive pulmonary disease (COPD), and restrictive lung diseases.

Explanation

Spirometry is a pulmonary function test that measures the amount and speed of air that can be inhaled and exhaled. FVC (Forced Vital Capacity) is one of the parameters measured during spirometry. It represents the maximum amount of air a person can forcefully exhale after taking a deep breath. FVC is an important measurement as it provides information about lung function and can help diagnose and monitor respiratory conditions such as asthma, chronic obstructive pulmonary disease (COPD), and restrictive lung diseases.

7. A patient was evaluated in a pulmonary function laboratory. At residual volume, a 2.5 l bag was attached to the patient's mouthpiece. The bag contained 0.8% He. The patient breathed into and out of the bag for 2 minutes, after which the He concentration in the bag was measured and found to be 0.55%. The patient's residual volume was:

0.9 l

1.08 l

1.14 l

1.22 l

Con(orig) - Con(final) / Con(final) X Vol(bag) = .25/.55 X 2.5= 1.137

Explanation

Con(orig) - Con(final) / Con(final) X Vol(bag) = .25/.55 X 2.5= 1.137

8. Chest X-rays of patients with emphysema show an elongated mediastinum. This is the result of:

Elastase breaking down the covering of the mediastinum.

Descent of the floor of the diaphragm

Cardiac failure

The correct answer is "descent of the floor of the diaphragm." In patients with emphysema, the lungs become hyperinflated due to the destruction of the alveolar walls. This hyperinflation causes the diaphragm to flatten and descend, resulting in an elongated mediastinum on chest X-rays. Elastase breaking down the covering of the mediastinum is not a known cause of an elongated mediastinum, and cardiac failure is not typically associated with this finding.

Explanation

The correct answer is "descent of the floor of the diaphragm." In patients with emphysema, the lungs become hyperinflated due to the destruction of the alveolar walls. This hyperinflation causes the diaphragm to flatten and descend, resulting in an elongated mediastinum on chest X-rays. Elastase breaking down the covering of the mediastinum is not a known cause of an elongated mediastinum, and cardiac failure is not typically associated with this finding.

9. In emphysema, which of the following would be expected to be below normal (less positive or more negative than normal)?

Airway resistance

Lung compliance

Intrapleural pressure

FEV1

B, C, and D above

FEV1 stands for Forced Expiratory Volume in 1 second, which is a measure of the maximum amount of air a person can forcefully exhale in one second. In emphysema, the air sacs in the lungs become damaged, causing them to lose their elasticity. This leads to a decrease in lung function and a reduction in the ability to exhale air effectively. Therefore, it is expected that FEV1 would be below normal in emphysema.

Explanation

FEV1 stands for Forced Expiratory Volume in 1 second, which is a measure of the maximum amount of air a person can forcefully exhale in one second. In emphysema, the air sacs in the lungs become damaged, causing them to lose their elasticity. This leads to a decrease in lung function and a reduction in the ability to exhale air effectively. Therefore, it is expected that FEV1 would be below normal in emphysema.

10. A premature baby with difficulty breathing probably has:

An increased FRC.

An increased TLC

A decreased RV

A and C.

premature baby, less surfactant, therefore, more surface tension, therefore smaller alveoli and therefore smaller RV

Explanation

premature baby, less surfactant, therefore, more surface tension, therefore smaller alveoli and therefore smaller RV

11. A coal miner went to his local clinic for chronic shortness of breath. His arterial oxygen saturation was 76% (below normal) and his esophageal pressure, an estimate of intrapleural pressure, was normal. In addition, his FEV1/FRC was 0.8. His residual volume was probably:

Below normal

Normal

Above normal

FEV1/FRC would be less than .8 in obstructive. Obstructive would have Increase in RV
interpleaural pressure is normal, in restrictive it would be changed (more negative) as the lung tried to recoil away from it

Explanation

FEV1/FRC would be less than .8 in obstructive. Obstructive would have Increase in RV
interpleaural pressure is normal, in restrictive it would be changed (more negative) as the lung tried to recoil away from it

12. A woman was evaluated in a whole body plethysmograph on a day when the barometric pressure was 752 mmHg. At residual volume, she inspired against a closed mouthpiece and airway pressure fell to 724 mmHg. During this inspiratory maneuver, 120 ml of air was expelled from the phethysmograph. Her residual volume was:

2.1 l

2.8 l

3.1 l

3.8 l

.120 / [(752-724) /752]

Explanation

.120 / [(752-724) /752]