Deck 11: Ventilation

Question 1

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

A)1, 2, and 3
B)1 and 2 only
C)1 and 3 only
D)2 and 3 only

Answer 1

A

Question 2

A lung that loses elastic fibers would exhibit which of the following characteristics?

A) Decreased airways resistance
B) Decreased pulmonary vascular resistance
C) Increased airway resistance
D) Increased pulmonary compliance

Answer 2

D
Explanation: Increased compliance results primarily from loss of elastic fibers, which occurs in emphysema.

Question 3

Which of the following pressures vary throughout the normal breathing cycle?
1) Alveolar pressure (P_alv)
2) Body surface pressure (P_bs)
3) Mouth pressure (P_ao)
4) Pleural pressure (P_pl)

A)1, 2, 3, and 4
B)2, 3, and 4 only
C)2 and 4 only
D)1 and 4 only

Answer 3

D

Question 4

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

A) Approximately 30% of the VC
B) Approximately 40% of the total lung capacity (TLC)
C) Approximately 70% of the VC
D) Approximately 90% of the VC

Question 5

How is compliance calculated?

A) Change in pressure/change in flow
B) Change in pressure/change in volume
C) Change in volume/change in flow
D) Change in volume/change in pressure

Question 6

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

A) It is positive during inspiration and negative during expiration.
B) It is the same as intrapleural pressure (P_pl).
C) It is negative during inspiration and positive during expiration.
D) It always remains less than atmospheric pressure.

Question 7

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

A) Transpulmonary pressure gradient (P_alv - P_pl)
B) Transthoracic pressure gradient (P_pl - P_bs)
C) Transcardiac pressure gradient (P_ca - P_alv)
D) Transrespiratory pressure gradient (P_alv - P_ao)

Question 8

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:

A) inspiratory reserve volume (IRV).
B) vital capacity (VC).
C) residual volume (RV).
D) tidal volume (V_T).

Question 9

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

A) Midinspiration
B) End-expiration
C) End-inspiration
D) Mid-expiration

Question 10

A fibrotic lung would exhibit which of the following characteristics?

A) Decreased airway resistance
B) Decreased lung compliance
C) Decreased PVR
D) Decreased surface tension

Question 11

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

A) Decrease compliance
B) Decrease surface tension
C) Increase elastance
D) Increase resistance

Question 12

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

A) Transcanadian pressure gradient (P_pc - P_ks)
B) Transpulmonary pressure gradient (P_alv - P_pl)
C) Transrespiratory pressure gradient (P_alv - P_ao)
D) Transthoracic pressure gradient (P_pl - P_bs)

Question 13

Normal lung compliance is approximately which of the following?

A) 0.01 L/cm H₂O
B) 0.20 L/cm H₂O
C) 2.00 L/cm H₂O
D) 10.00 L/cm H₂O

Question 14

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

A) P_alv is less than at the airway opening.
B) P_alv is the same as at the airway opening.
C) P_alv is greater than at the airway opening.
D) Airway pressure is greater than P_alv.

Question 15

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

A) Alveolar aphasia
B) Hysteresis
C) Pleural pressure variance
D) Transpulmonary pressures

Question 16

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

A) P_alv
B) P_pl
C) P_ao
D) P_bs

Question 17

What happens during normal inspiration?
1) The P_pl increases further below atmospheric pressure.
2) The transpulmonary pressure gradient widens.
3) P_alv drops below that at the airway opening.

A)1 and 2 only
B)2 and 3 only
C)1 only
D)1 and 3 only

Question 18

Which of the following are effects of surface tension forces in the air-filled lung?
1) It increases the elastic recoil of the lung (promoting collapse).
2) It makes the lung harder to inflate than if it were filled with fluid.
3) It decreases the lung's elasticity as volume increases.

A)1 and 2 only
B)2 and 3 only
C)1 and 3 only
D)1, 2, and 3

Question 19

What is the primary function of the lungs?

A) Convert angiotensin I to angiotensin II.
B) Filter pulmonary blood.
C) Gas exchange.
D) Remove carbon monoxide (CO).

Question 20

What forces must be overcome to move air into the respiratory system?
1) Tissue movement
2) Elastic forces of lung tissue
3) Airway resistance
4) Surface tension forces

A)1, 2, and 3 only
B)2 and 4 only
C)4 only
D)1, 2, 3, and 4

Question 21

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

A) Nose, mouth, and large airways
B) Respiratory bronchioles
C) Terminal bronchioles
D) Terminal respiratory unit

Question 22

In healthy individuals, what may lead to airway collapse?

A) Increased lung recoil
B) Significantly decreased surfactant
C) Maximal inspiration to TLC
D) Forced exhalation to RV

Question 23

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?

A) Decrease in the area of the volume-pressure curve
B) Decrease in the slope of the volume-pressure curve
C) Increase in the area of the volume-pressure curve
D) Increase in the slope of the volume-pressure curve

Question 24

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

A) Alveolar recruitment has its greatest effect on flow.
B) Halving the tube radius will require a 16-time increase in driving pressure.
C) Large jumps in driving pressure are needed to overcome airway narrowing.
D) The driving pressure varies directly with the airway circumference.

Question 25

On inspecting a volume-pressure curve for a patient with restrictive lung disease, which of the following abnormalities would you expect to find?
1) Decrease in the slope of the volume-pressure curve
2) Increase in the area of the volume-pressure curve
3) Positive P_pl during exhalation

A)2 only
B)1, 2, and 3
C)1 and 2 only
D)1 and 3 only

Question 26

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

A) Most volunteer subjects cannot understand the procedure used.
B) Respiratory muscle activity contributes to inflation resistance.
C) The respiratory muscles (diaphragm, etc.) must be paralyzed.
D) The subjects used to make the measurements must be unconscious.

Question 27

Normal R_aw is approximately which of the following?

A) 0.1 to 0.2 cm H₂O/L/sec
B) 0.5 to 2.5 cm H₂O/L/sec
C) 15.0 to 20.0 cm H₂O/L/sec
D) 20.0 to 25.0 cm H₂O/L/sec

Question 28

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

A) As gas travels from the EPP to the mouth, greater expiratory effort increases flow.
B) At the EPP, pressure inside the airway exceeds P_pl.
C) The EPP normally occurs at volumes greatly below the FRC.
D) Upstream from the EPP (toward the alveoli), P_pl exceeds pressure in the airway.

Question 29

Which of the following statements about R_aw is true?

A) The greater the lung volume, the greater is the R_aw.
B) The greater the lung volume, the less is the R_aw.
C) As lung volume decreases toward RV, the R_aw drops.
D) As lung volume increases toward TLC, the R_aw rises.

Question 30

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

A) 0.1 L/cm H₂O
B) 0.2 L/cm H₂O
C) 1.0 L/cm H₂O
D) 2.0 L/cm H₂O

Question 31

Which of the following factors affects R_aw?
1) Pattern of gas flow (e.g., laminar vs. turbulent)
2) Characteristics of the gas being breathed
3) Diameter and length of the airways
4) Variations in lung compliance

A)1, 2, and 3 only
B)2 and 4 only
C)4 only
D)1, 2, 3, and 4

Question 32

Which of the following factors would tend to increase the elastic component of the work of breathing?
1) Decreased compliance of the lungs or thorax
2) High frequencies of breathing
3) Increased V_T

A)1 and 3 only
B)1, 2, and 3
C)2 and 3 only
D)1 and 2 only

Question 33

In order to inspire to a lung volume greater than approximately 70% of TLC, the inspiratory muscles must overcome:

A) the recoil of the lungs.
B) the recoil of both the lungs and the chest wall.
C) the recoil of both the chest walls.
D) the recoil of the alveoli.

Question 34

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

A) Change in pressure/flow
B) Change in pressure $\times$ change in flow
C) Change in pressure $\times$ change in volume
D) Change in volume/change in pressure

Question 35

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

A) 20%
B) 30%
C) 40%
D) 50%

Question 36

How is airway resistance (R_aw) computed?

A) Change in pressure/change in volume
B) Change in pressure/flow
C) Change in volume/change in pressure
D) Change in volume/change in pressure

Question 37

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

A) The airways to collapse
B) The alveoli to expand
C) The chest wall to expand
D) The lungs to expand

Question 38

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

A) Airway resistance
B) Lung compliance
C) Surface tension
D) Tissue elastance

Question 39

In traditional physical terms, how is work defined?

A) Force $\times$ distance
B) Force $\times$ time
C) Mass $\times$ acceleration
D) Mass $\times$ force

Question 40

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

A) Exhalation will be passive, due to inspiratory stored potential energy.
B) Exhalation will only require 40% of the energy expended for inspiration.
C) Exhalation will be the result of accessory respiratory muscle use.
D) Exhalation will generally take half the time of inspiration.

Question 41

A normal 150-lb man is breathing at a rate of 17 with a tidal volume of 450 ml. By estimation, what is his approximate alveolar ventilation?

A) 7.65 L/min
B) 5.10 L/min
C) 3.85 L/min
D) 2.60 L/min

Question 42

Which of the following factors would tend to increase the frictional component of the work of breathing?
1) Decreased compliance of the lungs or thorax
2) High frequencies of breathing
3) Increased R_aw

A)1 and 2 only
B)1, 2, and 3
C)1 and 3 only
D)2 and 3 only

Question 43

Blockage of the pulmonary arterial circulation to a portion of the lung would cause which of the following?

A) Decrease in anatomical dead space
B) Decrease in physiologic dead space
C) Increase in alveolar dead space
D) Increase in anatomical dead space

Question 44

For a given transpulmonary pressure gradient and inflation time, which of the following lung units would exhibit the greatest change in volume?

A) A unit with high resistance and low compliance
B) A unit with high resistance and normal compliance
C) A unit with normal resistance and low compliance
D) A unit with normal resistance and normal compliance

Question 45

A patient has a V_T of 625 ml and a physiological dead space of 275 ml and is breathing at a frequency of 16/min. What is the alveolar ventilation (V_A)?

A) 3000 ml/min
B) 4400 ml/min
C) 5600 ml/min
D) 7000 ml/min

Question 46

Which of the following will cause an increase in the pressure energy required for inspiration?
1) Increased compliance
2) Increased flow
3) Increased resistance
4) Increased volume

A)1 and 2 only
B)2 and 4 only
C)2, 3, and 4 only
D)1, 2, 3, and 4

Question 47

If a patient has a V_T of 370 ml and a respiratory rate of 20 breaths/min, what is the minute ventilation?

A) 2.40 L/min
B) 3.70 L/min
C) 6.45 L/min
D) 7.40 L/min

Question 48

Which of the following lung units would empty and fill most slowly?

A) A unit with high resistance and high compliance
B) A unit with high resistance and low compliance
C) A unit with low resistance and high compliance
D) A unit with low resistance and low compliance

Question 49

Which of the following statements are true about pressure differences in the upright lung?
1) P_pl increases from lung apex to base.
2) The apical alveoli resting volume is less than at the base.
3) The transpulmonary pressure gradient is greatest at the apex.

A)1 and 3 only
B)1, 2, and 3
C)2 and 3 only
D)1 and 2 only

Question 50

In a normal individual lying on the right side (right side down), which of the following conditions would be true?

A) Both lungs would receive nearly equal ventilation.
B) The left lung would receive the most ventilation.
C) The right lung would receive the most ventilation.
D) There is inadequate information to make a decision.

Question 51

Regional factors affecting the distribution of gas in the normal lung result in which of the following?

A) More ventilation goes to the apexes and lung periphery.
B) More ventilation goes to the apexes and lung core.
C) More ventilation goes to the bases and lung core.
D) More ventilation goes to the bases and lung periphery.

Question 52

Given a constant resistance, how will increasing the compliance of a lung unit alter gas movement into and out of the alveolus?

A) Both filling and emptying will be slower.
B) The alveolus will fill and empty more quickly.
C) The alveolus will fill more quickly but empty more slowly.
D) The alveolus will fill more slowly but empty more quickly.

Question 53

Compared to a normal individual, when a patient with a severe obstructive impairment such as emphysema increases ventilation, which of the following occurs?

A) Carbon dioxide production falls as anaerobic metabolism increases.
B) Oxygen consumption increases at a faster rate than normal.
C) Oxygen consumption rises faster than carbon dioxide production.
D) The anaerobic threshold is reached later than normal.

Question 54

In individuals with disorders characterized by an increased frictional work of breathing, such as emphysema, which of the following breathing patterns results in the minimum work?

A) Rapid and deep breathing
B) Rapid and shallow breathing
C) Slow and deep breathing
D) Slow and shallow breathing

Question 55

Which of the following occurs during normal inspiration?

A) Alveoli at the apexes expand less than those at the bases.
B) Alveoli at the apexes expand more than those at the bases.
C) Alveoli at the bases expand less than those at the apexes.
D) Central alveoli expand more than those at the periphery.

Question 56

Which of the following statements applies to a lung unit with higher resistance than normal?

A) A given volume change will require less of a pressure change.
B) It will fill and empty more rapidly than a normal lung unit.
C) There will be less volume change for a given pressure change.
D) Volume to this area will remain the same under all conditions.

Question 57

What is the gas that is wasted during normal ventilation called?

A) Alveolar ventilation
B) Bronchial ventilation
C) Conducting ventilation
D) Dead space ventilation

Question 58

Which of the following formulas are used to compute the time constant of a lung unit?

A) Change in pressure $\times$ flow
B) Compliance/resistance
C) Resistance/elastance
D) Resistance $\times$ compliance

Question 59

In a normal individual, what is the oxygen cost of breathing as a percentage of the body's total oxygen consumption?

A) 5%
B) 10%
C) 20%
D) 35%

Question 60

In patients with small-airway disease breathing at higher than normal frequencies, what is likely to happen?
1) Dynamic compliance drops.
2) Oxygen consumption decreases.
3) The distribution of ventilation worsens.
4) The work of breathing increases.

A)1 and 2 only
B)1, 2, and 4 only
C)2, 3, and 4 only
D)1, 2, 3, and 4

Question 61

How can the body effectively compensate for an increased V_Dphy?

A) Decreased drive to breath
B) Decreased respiratory rate
C) Increased respiratory rate
D) Increased tidal volume

Question 62

What is ventilation in excess of metabolic needs called?

A) Hyperpnea
B) Hyperventilation
C) Hypopnea
D) Hypoventilation

Question 63

In what portion of the lungs does alveolar dead space normally occur?

A) Apexes
B) Bases
C) Middle portions of the lungs
D) Terminal respiratory units

Question 64

Given a constant carbon dioxide production, how will changing the level of V_A affect the PaCO₂?

A) A decrease in _A will decrease PaCO₂
B) An increase in _A will decrease PaCO₂
C) An increase in _A will increase PaCO₂
D) PaCO₂ is unaffected by changes in V_A

Question 65

What is the normal increase in ventilation that occurs with increased metabolic rates called?

A) Hyperpnea
B) Hyperventilation
C) Hypopnea
D) Hypoventilation

Question 66

For carbon dioxide levels to remain constant during exercise, which of the following factors must be elevated?

A) Alveolar ventilation
B) Dead space ventilation
C) Hemoglobin
D) Bicarbonate

Question 67

What is the single best indicator of the adequacy or effectiveness of alveolar ventilation?

A) PaO₂
B) PAO₂
C) PaCO₂
D) V_T

Question 68

In normal individuals, approximately what fraction of the V_T is wasted ventilation (does not participate in gas exchange)?

A) One-third of the tidal volume
B) Two-thirds of the tidal volume
C) One-half the of tidal volume
D) One-quarter of the tidal volume

Question 69

Which of the following diseases or disorders is most likely to result in an increased V_D/V_T ratio?

A) Atelectasis
B) Pneumonia
C) Pulmonary embolus
D) Pulmonary fibrosis

Question 70

What is used for setting optimal PEEP on a ventilator?

A) Pressure-volume curve
B) Flow-volume curve
C) Patient's height and weight
D) The disease state the patient is in

Question 71

Which of the following causes gas to flow into and out of the alveoli during breathing?

A) Transrespiratory system pressure (P_TR)
B) Intrapleural pressure (P_pl)
C) Transpulmonary pressure (P_TP)
D) Transmural pressure (P_tm)

Question 72

Under resting metabolic conditions, how much carbon dioxide does a normal adult produce per minute?

A) 150 ml/min
B) 200 ml/min
C) 250 ml/min
D) 300 ml/min

Question 73

Where is R_aw highest in the airway of the human body?

A) Terminal bronchioles
B) Carina
C) Left lower lobe
D) Nose, mouth, and large airways

Question 74

Which is the correct formula to calculate the alveolar minute ventilation of a spontaneously breathing subject?

A) f $\times$ V_DS/V_T
B) f $\times$ V_T
C) f $\times$ (V_T - V_DSphys)
D) f $\times$ (V_T + V_DSphys)

Question 75

Hypoventilation is defined as:

A) decreased tidal volume.
B) low-blood oxygen level.
C) very slow respiratory rate.
D) elevated blood carbon dioxide level.

Question 76

A patient has a PCO₂ of 56 mm Hg. Based on this information, what can be concluded?

A) The patient is hyperventilating.
B) The patient is hypoventilating.
C) The patient's breathing rate is fast.
D) The patient's V_T is low.

Question 77

In clinical practice measuring the physiologic dead space ventilation is achieved by using which formula?

A) Bernoulli's equation
B) Modified Bohr equation
C) Modified Shunt equation
D) Reynold's equation

Question 78

What is ventilation that is insufficient to meet metabolic needs called?

A) Hypoventilation
B) Hyperventilation
C) Hyperpnea
D) Hypopnea