Question 1

Which of the following factors would tend to increase the elastic component of the work of breathing? I.decreased compliance of the lungs or thorax II.high frequencies of breathing III.increased V_T

Accepted Answer

Decreased compliance of the lungs or thorax would require more force to expand the lungs during inhalation, increasing the elastic component of the work of breathing. Increased resistance (V_T) in the airways would also increase the elastic component of breathing work. High frequencies of breathing may increase the work of breathing, but it is more related to increased resistance or dead space than to the elastic component. Therefore, options B and C are incorrect.

Question 2

Most of the drop in pressure due to frictional resistance to gas flow occurs in what region?

Accepted Answer

The majority of the drop in pressure due to frictional resistance to gas flow occurs in the nose, mouth, and large airways, as these are the areas where the airflow velocity is highest and the cross-sectional area is relatively low compared to the smaller airways, leading to higher resistance.

Question 3

Exhalation below the resting level requires active muscular effort in order to overcome what tendency?

Accepted Answer

The chest wall has a natural tendency to expand outward, so active muscular effort is needed to exhale below the resting level to counteract this tendency.

Question 4

On inspecting a volume-pressure curve for a patient with restrictive lung disease, which of the following abnormalities would you expect to find? I.decrease in the slope of the volume-pressure curve II.increase in the area of the volume-pressure curve III.positive P_pl during exhalation

Accepted Answer

In restrictive lung disease, the lungs have reduced compliance, leading to a decrease in the slope of the volume-pressure curve and an increase in the area under the curve. However, there is no specific indication of a positive PLAT pressure (P_pl) during exhalation in restrictive lung disease.

Question 5

In health, about what proportion of the total work of breathing is attributable to frictional resistance to gas and tissue movement?

Accepted Answer

Frictional resistance to gas and tissue movement accounts for about one-third of the total work of breathing in health.

Question 6

In traditional physical terms, how is work defined?

Accepted Answer

Work is defined as the force applied to an object multiplied by the distance over which the force is applied. This can be represented by the equation W=F1S1, where W is work, F1 is the force applied, and S1 is the distance over which the force is applied. The option A correctly represents this definition. Option B and C are incorrect as they do not include distance in the equation, and option D is incorrect as it includes mass instead of distance in the equation.

Question 7

Which of the following statements about Raw is true?

Accepted Answer

The greater the lung volume, the less is the airway resistance (Raw), because as the lungs expand, the airways are pulled open wider, reducing resistance to airflow.

Question 8

Total lung-thorax compliance in normal subjects is about what level?

Accepted Answer

In healthy adults, the compliance of the lungs and chest wall are approximately equal at 0.2 L/cm H₂O. However, because the lungs are contained within the thorax, the two systems act as springs pulling against each other. This reduces the compliance of the system to approximately half that of the individual components, or 0.1 L/cm H₂O.

Question 9

Which of the following statements about the equal pressure point (EPP) is true?

Accepted Answer

At some point along the airway, the pressure inside equals the pressure outside in the pleural space. This point is referred to as the EPP. Downstream from this point, pleural pressure exceeds the airway pressure. The resulting positive transmural pressure gradient causes airway compression and can lead to actual collapse. Airway compression increases expiratory airway resistance and limits flow. At the EPP, greater expiratory effort only increases pleural pressure, further restricting flow. In airways of healthy subjects, the EPP occurs only with forced exhalation and at low lung volumes.

Question 10

How is airway resistance (Raw) computed?

Accepted Answer

Airway resistance (Raw) is computed by dividing the change in pressure by the flow rate. This is expressed as Raw = ΔP/F, where ΔP represents the change in pressure and F represents the flow rate. Therefore, the correct choice is B, which states that Raw is calculated as change in pressure/flow.

Question 11

Which of the following factors affects Raw?
I.pattern of gas flow (e.g., laminar versus turbulent)II.characteristics of the gas being breathed
III.diameter and length of the airways
IV.variations in lung compliance

Accepted Answer

Factors affecting airway resistance (Raw) include the pattern of gas flow (laminar versus turbulent), characteristics of the gas being breathed (e.g., density and viscosity), and the diameter and length of the airways. Lung compliance affects the ease with which the lungs can expand but does not directly influence airway resistance.

Question 12

A patient in the pulmonary lab has the following test results: compliance of the lung (C_L) = 0.20 L/cm H₂O; compliance of the lung and thorax = 0.04 L/cm H₂O. What is the patient's chest wall compliance?

Accepted Answer

Chest wall compliance is calculated using the formula 1/Ctotal = 1/Clung + 1/Cchest wall. Given the compliance of the lung (Clung) is 0.20 L/cm H2O and the compliance of the lung and thorax (Ctotal) is 0.04 L/cm H2O, solving for Cchest wall gives a compliance of 0.05 L/cm H2O.

Question 13

Why is the total mechanical work of breathing difficult to assess during spontaneous breathing?

Accepted Answer

Respiratory muscle activity contributes to inflation resistance, which makes it difficult to assess the total mechanical work of breathing during spontaneous breathing.

Question 14

Normal Raw is approximately which of the following?

Accepted Answer

According to the given options, the appropriate value of Normal Raw is in the range of 0.5 to 2.5 cm H2O/L/sec.

Question 15

For healthy individuals at rest, which of the following statements about exhalation is true?

Accepted Answer

Exhalation at rest is an active process, but it is passive in the sense that it does not require the contraction of any specific muscles. During inspiration, the diaphragm and external intercostal muscles contract, creating space for the lungs to expand. This stretching of the lungs creates a pressure gradient that draws air in. During exhalation, these muscles relax, and the elastic properties of the lungs and surrounding tissues cause them to recoil, which pushes air out of the lungs. This process does not require any additional energy expenditure beyond what was needed for inspiration.

Question 16

Which of the following formulas is used to compute the mechanical work of breathing?

Accepted Answer

The formula used to compute the mechanical work of breathing is change in pressure times change in volume. This is represented by the formula: Work = ΔP × ΔV. Option C represents this formula correctly, where F1 is the initial fraction of inspired oxygen and F10 is the fraction of inspired oxygen at 10 liters per minute flowrate, but they are not relevant to the calculation of mechanical work of breathing. Options A, B, and D are incorrect as they do not represent the correct formula for calculating the mechanical work of breathing.

Question 17

What is the term for the impedance to ventilation caused by the movement of gas through the conducting system of the lungs?

Accepted Answer

Airway resistance refers to the constriction or obstruction of airways, which can impede the flow of air into and out of the lungs. This can be caused by factors such as bronchoconstriction, inflammation, and mucus buildup.

B) Lung compliance refers to the ability of the lungs to expand and contract in response to changes in pressure. It is a measure of how easily the lungs can be filled with air and how readily they return to their resting state.

C) Surface tension refers to the attractive forces between the molecules at an air-liquid interface. In the lungs, this can affect the ease with which alveoli can be inflated and deflated, and can contribute to lung collapse in certain conditions.

D) Tissue elastance refers to the resistance of lung tissue to being stretched or compressed. It is a measure of how "stiff" the lungs are, and can be affected by factors such as fibrosis or emphysema.

Question 18

On inspecting a volume-pressure curve of the lungs and thorax, an increase in the mechanical work of breathing above normal would always be indicated by which of the following?

Accepted Answer

An increase in mechanical work of breathing would indicate an increase in the effort needed to move air in and out of the lungs. This would result in an increase in the area of the volume-pressure curve as the thoracic and lung volumes would need to change to produce the same pressure. The other choices do not necessarily indicate changes in effort or work of breathing.

Question 19

In healthy individuals, what may lead to airway collapse?

Accepted Answer

Forced exhalation to residual volume (RV) can lead to airway collapse due to increased intrathoracic pressure and decreased airway pressure, which can cause the airways to narrow or collapse, especially in smaller airways.

Question 20

According to Poiseuille's law, which of the following statements are true if we wish to maintain a constant flow of gases?

Accepted Answer

According to Poiseuille's law, the flow of gases is directly proportional to the fourth power of the tube radius. Therefore, if the tube radius is halved, the flow reduces to 1/16 of its original value, and to maintain constant flow, a 16-time increase in driving pressure is required.

Quiz 10: Ventilation

Which of the following factors would tend to increase the elastic component of the work of breathing? I.decreased compliance of the lungs or thorax II.high frequencies of breathing III.increased V_T

Most of the drop in pressure due to frictional resistance to gas flow occurs in what region?

Exhalation below the resting level requires active muscular effort in order to overcome what tendency?

On inspecting a volume-pressure curve for a patient with restrictive lung disease, which of the following abnormalities would you expect to find? I.decrease in the slope of the volume-pressure curve II.increase in the area of the volume-pressure curve III.positive P_pl during exhalation

In health, about what proportion of the total work of breathing is attributable to frictional resistance to gas and tissue movement?

In traditional physical terms, how is work defined?

Which of the following statements about Raw is true?

Total lung-thorax compliance in normal subjects is about what level?

Which of the following statements about the equal pressure point (EPP) is true?

How is airway resistance (Raw) computed?

Which of the following factors affects Raw? I.pattern of gas flow (e.g., laminar versus turbulent) II.characteristics of the gas being breathed III.diameter and length of the airways IV.variations in lung compliance

A patient in the pulmonary lab has the following test results: compliance of the lung (C_L) = 0.20 L/cm H₂O; compliance of the lung and thorax = 0.04 L/cm H₂O. What is the patient's chest wall compliance?

Why is the total mechanical work of breathing difficult to assess during spontaneous breathing?

Normal Raw is approximately which of the following?

For healthy individuals at rest, which of the following statements about exhalation is true?

Which of the following formulas is used to compute the mechanical work of breathing?

What is the term for the impedance to ventilation caused by the movement of gas through the conducting system of the lungs?

On inspecting a volume-pressure curve of the lungs and thorax, an increase in the mechanical work of breathing above normal would always be indicated by which of the following?

In healthy individuals, what may lead to airway collapse?

According to Poiseuille's law, which of the following statements are true if we wish to maintain a constant flow of gases?

Quiz 10: Ventilation

Which of the following factors would tend to increase the elastic component of the work of breathing? I.decreased compliance of the lungs or thorax II.high frequencies of breathing III.increased VT

Most of the drop in pressure due to frictional resistance to gas flow occurs in what region?

Exhalation below the resting level requires active muscular effort in order to overcome what tendency?

On inspecting a volume-pressure curve for a patient with restrictive lung disease, which of the following abnormalities would you expect to find? I.decrease in the slope of the volume-pressure curve II.increase in the area of the volume-pressure curve III.positive Ppl during exhalation

In health, about what proportion of the total work of breathing is attributable to frictional resistance to gas and tissue movement?

In traditional physical terms, how is work defined?

Which of the following statements about Raw is true?

Total lung-thorax compliance in normal subjects is about what level?

Which of the following statements about the equal pressure point (EPP) is true?

How is airway resistance (Raw) computed?

Which of the following factors affects Raw? I.pattern of gas flow (e.g., laminar versus turbulent) II.characteristics of the gas being breathed III.diameter and length of the airways IV.variations in lung compliance

A patient in the pulmonary lab has the following test results: compliance of the lung (CL) = 0.20 L/cm H2O; compliance of the lung and thorax = 0.04 L/cm H2O. What is the patient's chest wall compliance?

Why is the total mechanical work of breathing difficult to assess during spontaneous breathing?

Normal Raw is approximately which of the following?

For healthy individuals at rest, which of the following statements about exhalation is true?

Which of the following formulas is used to compute the mechanical work of breathing?

What is the term for the impedance to ventilation caused by the movement of gas through the conducting system of the lungs?

On inspecting a volume-pressure curve of the lungs and thorax, an increase in the mechanical work of breathing above normal would always be indicated by which of the following?

In healthy individuals, what may lead to airway collapse?

According to Poiseuille's law, which of the following statements are true if we wish to maintain a constant flow of gases?

Which of the following factors would tend to increase the elastic component of the work of breathing? I.decreased compliance of the lungs or thorax II.high frequencies of breathing III.increased V_T

On inspecting a volume-pressure curve for a patient with restrictive lung disease, which of the following abnormalities would you expect to find? I.decrease in the slope of the volume-pressure curve II.increase in the area of the volume-pressure curve III.positive P_pl during exhalation

A patient in the pulmonary lab has the following test results: compliance of the lung (C_L) = 0.20 L/cm H₂O; compliance of the lung and thorax = 0.04 L/cm H₂O. What is the patient's chest wall compliance?