Question 1

During each cycle of normal resting ventilation, a volume of gas is moved into and out of the respiratory tract. This cyclical volume is called the:

Accepted Answer

Tidal volume (VT) is the volume of gas moved into and out of the respiratory tract during each cycle of normal resting ventilation. The other options describe different lung volumes but not the cyclical volume of gas moved in and out during normal breathing.

Question 2

Which of the following pressure gradients is responsible for the actual flow of gas into and out of the lungs during breathing?

Accepted Answer

The transrespiratory pressure gradient (P_alv - P_ao) is responsible for the flow of gas into and out of the lungs, as it represents the difference between alveolar pressure and airway opening pressure.

Question 3

What is the effect of surface tension forces in the air-filled lung?
I.It increases the elastic recoil of the lung (promoting collapse).
II.It makes the lung harder to inflate than if it were filled with fluid.
III.It decreases the lung's elasticity as volume increases.

Accepted Answer

Surface tension forces in the air-filled lung increase the elastic recoil of the lung, promoting its collapse, and make the lung harder to inflate than if it were filled with fluid. This is because the cohesive forces between liquid molecules at the air-liquid interface in the alveoli create a surface tension that resists expansion.

Question 4

What occurs at a lung volume equivalent to the functional residual capacity (FRC)? I.The forces of the chest wall and lungs are in balance. II.Chest wall expansion is offset by lung contraction. III.Opposing chest wall-lung forces generate negative P_pl.

Accepted Answer

At the functional residual capacity (FRC), the outward force of the chest wall is balanced by the inward recoil of the lungs, meaning both I and II are correct. Additionally, this balance of forces results in a negative intrapleural pressure, which is what III describes.

Question 5

During normal tidal ventilation, the transpulmonary pressure gradient (P_alv - P_pl) reaches its maximum value at what point in the cycle?

Accepted Answer

Transpulmonary pressure gradient (the difference between alveolar pressure and pleural pressure) reaches its maximum value at end-inspiration, when the alveolar pressure becomes more positive due to an increase in lung volume, and the negative pleural pressure is at its maximum.

Question 6

Which of the following statements about alveolar pressure (P_alv) during normal quiet breathing is true?

Accepted Answer

During inspiration, the diaphragm contracts and the volume of the thoracic cavity increases. This results in a decrease in alveolar pressure, which becomes negative relative to atmospheric pressure. During expiration, the diaphragm relaxes and the volume of the thoracic cavity decreases. This results in an increase in alveolar pressure, which becomes positive relative to atmospheric pressure. Therefore, option C is correct. Option A is incorrect because alveolar pressure is negative during inspiration and positive during expiration. Option B is incorrect because intrapleural pressure is always negative relative to atmospheric pressure, whereas alveolar pressure is negative during inspiration and positive during expiration. Option D is incorrect because alveolar pressure can become greater than atmospheric pressure during expiration.

Question 7

Which of the following pressure gradients is responsible for maintaining alveolar inflation?

Accepted Answer

The transpulmonary pressure gradient (difference between alveolar pressure and pleural pressure) is responsible for maintaining the inflation of the alveoli during respiration. This pressure gradient keeps the alveoli open and prevents their collapse.

Question 8

What happens during normal inspiration? I.The P_pl decreases further below atmospheric. II.The transpulmonary pressure gradient widens. III.P_alv drops below that at the airway opening.

Accepted Answer

During normal inspiration, the diaphragm contracts, increasing the volume of the thoracic cavity. This leads to a decrease in intrapulmonary pressure (below atmospheric pressure), causing air to flow into the lungs. The transpulmonary pressure gradient (the difference between the pressure inside the lungs and the pleural pressure) widens, facilitating lung expansion. Additionally, the pressure at the alveoli drops below that at the airway opening, ensuring air flows into the alveoli.

Question 9

Which of the following pressures vary throughout the normal breathing cycle? I.alveolar pressure (P_alv) II.body surface pressure (P_bs) III.mouth pressure (P_ao) IV.pleural pressure (P_pl)

Accepted Answer

Alveolar pressure (P_alv) and pleural pressure (P_pl) are the pressures that vary throughout the normal breathing cycle. Body surface pressure (P_bs) and mouth pressure (P_ao) remain relatively constant. Therefore, the correct answer is D, which includes only I and IV.

Question 10

What term is used to note the difference between inspiratory lung volume and expiratory lung volume at any given pressure?

Accepted Answer

Hysteresis refers to the difference between inspiratory and expiratory lung volumes at any given pressure. This occurs due to the changes in lung compliance and resistance during inhalation and exhalation. The other options, alveolar aphasia, pleural pressure variance, and transpulmonary pressures, do not directly relate to this concept.

Question 11

What is the primary function of the lungs?

Accepted Answer

The primary function of the lungs is gas exchange, which involves taking in oxygen and exhaling carbon dioxide.

Therefore, the correct answer is C.

Question 12

Which of the following pressures normally remains negative (relative to atmospheric pressure) during quiet breathing?

Accepted Answer

The pressure inside the pleural cavity (P_pl) normally remains negative (relative to atmospheric pressure) during quiet breathing. This negative pressure is necessary to keep the lungs inflated and to facilitate gas exchange in the alveoli. The other pressures listed may become positive or negative depending on the phase of breathing.

Question 13

How is compliance computed?

Accepted Answer

Compliance is defined as the change in volume per unit change in pressure. Therefore, the correct formula for compliance is change in volume divided by change in pressure. Hence, the correct choice is D - change in volume/change in pressure.

Question 14

During expiration, why does gas flow out from the lungs to the atmosphere?

Accepted Answer

During expiration, gas flows out from the lungs to the atmosphere because the pressure in the alveoli (P_alv) is greater than at the airway opening, driving the air out.

Question 15

The presence of surfactant in the alveoli tends to do which of the following?

Accepted Answer

Surfactant reduces surface tension in the alveoli, making it easier for them to expand during inspiration and decreasing the work required for breathing. It does not affect compliance, elastance, or resistance.

Question 16

A fibrotic lung would exhibit which of the following characteristics?

Accepted Answer

Fibrotic lung tissue is characterized by increased stiffness or rigidity, which results in decreased lung compliance. This means that the lungs are less able to expand and contract, which can lead to reduced oxygenation and ventilation. Choices A, C, and D are not characteristic of fibrotic lungs.

Question 17

Normal lung compliance is approximately which of the following?

Accepted Answer

Normal lung compliance is approximately 0.20 L/cm H2O. Option A is too low, Option C is too high, and Option D is an incorrect unit of measure (should be cm H2O, not cm).

Question 18

A lung that loses elastic fibers (as in emphysema) would exhibit which of the following characteristics?

Accepted Answer

In emphysema, the destruction of alveolar walls leads to a loss of elastic fibers, which results in increased pulmonary compliance. This means the lungs can expand more easily but have difficulty recoiling to expel air, contributing to air trapping and difficulty in breathing.

Question 19

At approximately what point during a maximum inspiration does the chest wall reach its natural resting level?

Accepted Answer

The chest wall reaches its natural resting level around 70% of the VC during a maximum inspiration. This is because at this point the lungs are inflated to their full capacity, causing the diaphragm and intercostal muscles to relax and return the chest wall to its resting position.

Question 20

What forces must be overcome to move air into the respiratory system?
I.tissue movement
II.elastic forces of lung tissue
III.airway resistance
IV.surface tension forces

Accepted Answer

All four forces must be overcome to move air into the respiratory system: tissue movement, elastic forces of lung tissue, airway resistance, and surface tension forces.

Quiz 10: Ventilation

During each cycle of normal resting ventilation, a volume of gas is moved into and out of the respiratory tract. This cyclical volume is called the:

Which of the following pressure gradients is responsible for the actual flow of gas into and out of the lungs during breathing?

What is the effect of surface tension forces in the air-filled lung? I.It increases the elastic recoil of the lung (promoting collapse) . II.It makes the lung harder to inflate than if it were filled with fluid. III.It decreases the lung's elasticity as volume increases.

What occurs at a lung volume equivalent to the functional residual capacity (FRC) ? I.The forces of the chest wall and lungs are in balance. II.Chest wall expansion is offset by lung contraction. III.Opposing chest wall-lung forces generate negative P_pl.

During normal tidal ventilation, the transpulmonary pressure gradient (P_alv - P_pl) reaches its maximum value at what point in the cycle?

Which of the following statements about alveolar pressure (P_alv) during normal quiet breathing is true?

Which of the following pressure gradients is responsible for maintaining alveolar inflation?

What happens during normal inspiration? I.The P_pl decreases further below atmospheric. II.The transpulmonary pressure gradient widens. III.P_alv drops below that at the airway opening.

Which of the following pressures vary throughout the normal breathing cycle? I.alveolar pressure (P_alv) II.body surface pressure (P_bs) III.mouth pressure (P_ao) IV.pleural pressure (P_pl)

What term is used to note the difference between inspiratory lung volume and expiratory lung volume at any given pressure?

What is the primary function of the lungs?

Which of the following pressures normally remains negative (relative to atmospheric pressure) during quiet breathing?

How is compliance computed?

During expiration, why does gas flow out from the lungs to the atmosphere?

The presence of surfactant in the alveoli tends to do which of the following?

A fibrotic lung would exhibit which of the following characteristics?

Normal lung compliance is approximately which of the following?

A lung that loses elastic fibers (as in emphysema) would exhibit which of the following characteristics?

At approximately what point during a maximum inspiration does the chest wall reach its natural resting level?

What forces must be overcome to move air into the respiratory system? I.tissue movement II.elastic forces of lung tissue III.airway resistance IV.surface tension forces

Quiz 10: Ventilation

During each cycle of normal resting ventilation, a volume of gas is moved into and out of the respiratory tract. This cyclical volume is called the:

Which of the following pressure gradients is responsible for the actual flow of gas into and out of the lungs during breathing?

What is the effect of surface tension forces in the air-filled lung? I.It increases the elastic recoil of the lung (promoting collapse) . II.It makes the lung harder to inflate than if it were filled with fluid. III.It decreases the lung's elasticity as volume increases.

What occurs at a lung volume equivalent to the functional residual capacity (FRC) ? I.The forces of the chest wall and lungs are in balance. II.Chest wall expansion is offset by lung contraction. III.Opposing chest wall-lung forces generate negative Ppl.

During normal tidal ventilation, the transpulmonary pressure gradient (Palv - Ppl) reaches its maximum value at what point in the cycle?

Which of the following statements about alveolar pressure (Palv) during normal quiet breathing is true?

Which of the following pressure gradients is responsible for maintaining alveolar inflation?

What happens during normal inspiration? I.The Ppl decreases further below atmospheric. II.The transpulmonary pressure gradient widens. III.Palv drops below that at the airway opening.

Which of the following pressures vary throughout the normal breathing cycle? I.alveolar pressure (Palv) II.body surface pressure (Pbs) III.mouth pressure (Pao) IV.pleural pressure (Ppl)

What term is used to note the difference between inspiratory lung volume and expiratory lung volume at any given pressure?

What is the primary function of the lungs?

Which of the following pressures normally remains negative (relative to atmospheric pressure) during quiet breathing?

How is compliance computed?

During expiration, why does gas flow out from the lungs to the atmosphere?

The presence of surfactant in the alveoli tends to do which of the following?

A fibrotic lung would exhibit which of the following characteristics?

Normal lung compliance is approximately which of the following?

A lung that loses elastic fibers (as in emphysema) would exhibit which of the following characteristics?

At approximately what point during a maximum inspiration does the chest wall reach its natural resting level?

What forces must be overcome to move air into the respiratory system? I.tissue movement II.elastic forces of lung tissue III.airway resistance IV.surface tension forces

What occurs at a lung volume equivalent to the functional residual capacity (FRC) ? I.The forces of the chest wall and lungs are in balance. II.Chest wall expansion is offset by lung contraction. III.Opposing chest wall-lung forces generate negative P_pl.

During normal tidal ventilation, the transpulmonary pressure gradient (P_alv - P_pl) reaches its maximum value at what point in the cycle?

Which of the following statements about alveolar pressure (P_alv) during normal quiet breathing is true?

What happens during normal inspiration? I.The P_pl decreases further below atmospheric. II.The transpulmonary pressure gradient widens. III.P_alv drops below that at the airway opening.

Which of the following pressures vary throughout the normal breathing cycle? I.alveolar pressure (P_alv) II.body surface pressure (P_bs) III.mouth pressure (P_ao) IV.pleural pressure (P_pl)