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Lange Pulmonary Physiology, 10e > Chapter 3 > Flashcards

Chapter 3 Flashcards

1
Q

What is alveolar ventilation?

A

The exchange of gas between the alveoli and the external environment.

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2
Q

How is alveolar ventilation defined?

A

As the volume of fresh air entering the alveoli per minute.

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3
Q

What factors influence lung volume?

A

The mechanics of the lungs and chest wall, and the activity of the muscles of inspiration and expiration.

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4
Q

What are the standard lung volumes?

A

Four standard lung volumes: Tidal Volume (VT), Residual Volume (RV), Expiratory Reserve Volume (ERV), Inspiratory Reserve Volume (IRV).

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5
Q

What is tidal volume (VT)?

A

The volume of air entering or leaving the nose or mouth per breath.

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6
Q

What is the typical tidal volume for a 70-kg adult?

A

About 500 mL per breath.

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7
Q

What is residual volume (RV)?

A

The volume of gas left in the lungs after a maximal forced expiration.

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8
Q

What is the typical residual volume for a healthy 70-kg adult?

A

About 1.5 L.

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9
Q

What is expiratory reserve volume (ERV)?

A

The volume of gas expelled during a maximal forced expiration following a normal tidal expiration.

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10
Q

What is the typical expiratory reserve volume for a healthy 70-kg adult?

A

About 1.5 L.

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11
Q

What is inspiratory reserve volume (IRV)?

A

The volume of gas inhaled during a maximal forced inspiration starting at the end of a normal tidal inspiration.

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12
Q

What is the typical inspiratory reserve volume for a healthy 70-kg adult?

A

About 2.5 L.

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13
Q

What is functional residual capacity (FRC)?

A

The volume of gas remaining in the lungs at the end of a normal tidal expiration.

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14
Q

What is the typical functional residual capacity for a healthy 70-kg adult?

A

About 3 L.

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15
Q

What is inspiratory capacity (IC)?

A

The volume of air inhaled during a maximal inspiratory effort starting at the end of a normal tidal expiration.

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16
Q

What is the typical inspiratory capacity for a healthy 70-kg adult?

A

About 3 L.

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17
Q

What is total lung capacity (TLC)?

A

The volume of air in the lungs after a maximal inspiratory effort.

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18
Q

What is the typical total lung capacity for a healthy 70-kg adult?

A

About 6 L.

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19
Q

What is vital capacity (VC)?

A

The volume of air expelled from the lungs during a maximal forced expiration following a maximal forced inspiration.

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20
Q

What is the typical vital capacity for a healthy 70-kg adult?

A

About 4.5 L.

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21
Q

What is the significance of measuring lung volumes?

A

It helps in diagnosing pathologic states and understanding normal physiological variations.

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22
Q

What happens to functional residual capacity (FRC) when changing from standing to supine?

A

FRC decreases.

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23
Q

What lung volumes cannot be measured with a spirometer?

A

Residual Volume (RV), Functional Residual Capacity (FRC), Total Lung Capacity (TLC).

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24
Q

What is the nitrogen-washout technique used for?

A

To determine lung volumes not measurable with spirometry.

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25
Q

What does the helium-dilution technique measure?

A

Lung volume by measuring the concentration of helium in the lungs.

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26
Q

Fill in the blank: The tidal volume (VT) is about ______ for a healthy 70-kg adult.

A

500 mL

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27
Q

Fill in the blank: The residual volume (RV) is about ______ for a healthy 70-kg adult.

A

1.5 L

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28
Q

True or False: The total lung capacity (TLC) is the sum of all four lung volumes.

A

True

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29
Q

Fill in the blank: The vital capacity (VC) is approximately ______ for a healthy 70-kg adult.

A

4.5 L

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30
Q

What is the formula to calculate the amount of solute?

A

Amount of solute(mg) = concentration of solute(mg/mL) × volume of solvent(mL)

This formula allows for the determination of solute quantity based on its concentration and the volume of solvent used.

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31
Q

What technique uses helium to determine lung volume?

A

Helium-dilution technique

Helium is used due to its low solubility in body tissues and its inability to diffuse out of blood.

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32
Q

Why is helium used in the helium-dilution technique?

A

Helium is not taken up by pulmonary capillary blood and does not diffuse out of the blood

This ensures that the total amount of helium remains constant during the test.

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33
Q

What happens during the helium-dilution test?

A

The helium concentration is monitored until it equilibrates between the lungs and the spirometer

The test concludes at the end of a normal tidal expiration.

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34
Q

What does FRC stand for?

A

Functional Residual Capacity

FRC is the volume of air remaining in the lungs after a normal tidal expiration.

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35
Q

How is FRC calculated in the helium-dilution technique?

A

FHEtVspi = FHEf (Vspf + VLf)

FHE represents the fractional concentration of helium, Vspi is the initial volume of the spirometer, and VLf is the lung volume at the end of the test.

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36
Q

What is a limitation of the nitrogen-washout and helium-dilution techniques?

A

Neither can measure trapped gas in the lungs

Trapped gas cannot be washed out or equilibrated due to closed airways.

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37
Q

What principle does body plethysmography use?

A

Boyle’s law

Boyle’s law states that pressure times volume is constant for a closed container at a constant temperature.

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38
Q

What equipment is used in body plethysmography?

A

An airtight chamber, pressure transducers, pneumotachograph

These components measure airflow and pressure changes during breathing.

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39
Q

What occurs during the plethysmography test?

A

The operator occludes the subject’s airway at end expiration, allowing measurement of FRC

This is done by observing pressure changes in the plethysmograph.

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40
Q

Define anatomic dead space.

A

The volume of the conducting airways where no gas exchange occurs

This volume corresponds to the conducting zone of the respiratory system.

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41
Q

How is the volume of gas entering the alveoli calculated?

A

VA = VT - VD

VA is the volume of gas reaching the alveoli, VT is the tidal volume, and VD is the dead space volume.

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42
Q

What is the relationship between minute volume and alveolar ventilation?

A

VA = VE - VD

VE is the minute volume and VD is the volume wasted in dead space.

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43
Q

What is the formula to calculate alveolar ventilation per minute?

A

n(VA) = n(VT) - n(VD)

n represents the breathing frequency in breaths per minute.

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44
Q

How can anatomic dead space be estimated?

A

1 mL of dead space per pound of ideal body weight

This estimation can also be matched to tables based on sex, age, height, and weight.

45
Q

What method is used to determine anatomic dead space?

A

Fowler’s method

This method analyzes expired nitrogen concentration after inhaling 100% oxygen.

46
Q

What happens to nitrogen concentration during Fowler’s method?

A

It initially registers 80% and falls to 0% upon inhaling 100% oxygen

The nitrogen concentration rises again during exhalation as a mixture of dead-space and alveolar gas.

47
Q

What happens to nitrogen concentration at the mouth when a subject breathes 100% oxygen?

A

It falls to zero.

This indicates that the initial exhaled gas contains no nitrogen.

48
Q

What is the initial nitrogen concentration in the expired gas after inhaling 100% oxygen?

A

0% nitrogen.

This is due to the undiluted 100% oxygen from the anatomic dead space.

49
Q

What is the ‘alveolar plateau’ in the context of expired gas?

A

The final portion of expired gas that comes solely from the alveoli.

Its nitrogen concentration is less than 80% due to dilution from inspired 100% oxygen.

50
Q

What method is rarely used clinically to determine anatomic dead space?

A

Fowler’s method.

This method is not effective for calculating alveolar dead space.

51
Q

Define alveolar dead space.

A

The volume of gas that enters unperfused alveoli per breath.

This includes alveoli that are ventilated but not perfused with venous blood.

52
Q

What is the physiologic dead space?

A

The sum of anatomic dead space and alveolar dead space.

It is calculated using the Bohr equation.

53
Q

How does the Bohr equation relate to dead space?

A

It determines the sum of anatomic and alveolar dead space.

The equation utilizes carbon dioxide measurements in expired gas.

54
Q

What is the significance of carbon dioxide in determining dead space?

A

Any measurable volume of carbon dioxide in expired gas must come from ventilated and perfused alveoli.

Inspired air in dead space contributes little to carbon dioxide levels.

55
Q

What does the term ‘end-tidal CO2’ refer to?

A

The carbon dioxide expelled at the end of a normal tidal expiration.

It is used to estimate the alveolar PCO2.

56
Q

What is the relationship between arterial PCO2 and end-tidal PCO2?

A

In patients without significant venous-to-arterial shunts, arterial PCO2 represents the mean PCO2 of perfused alveoli.

Significant differences indicate high alveolar dead space.

57
Q

How can anatomic dead space be altered?

A

By bronchoconstriction, bronchodilation, or traction/compression of airways.

These changes affect the volume of dead space.

58
Q

What factors determine the levels of oxygen and carbon dioxide in alveolar gas?

A

Alveolar ventilation, oxygen consumption (V˙O2), and carbon dioxide production (V˙CO2).

These factors are crucial for maintaining gas exchange.

59
Q

According to Dalton’s law, how is the partial pressure of a gas calculated?

A

It is equal to its fractional concentration times the total pressure of all gases in the mixture.

This principle is fundamental in understanding gas mixtures.

60
Q

What is the partial pressure of oxygen (PO2) in dry atmospheric air at standard barometric pressure?

A

159 mm Hg.

This is calculated as 0.2093 multiplied by 760 mm Hg.

61
Q

What is the humidified PO2 of inspired air?

A

149 mm Hg.

This accounts for the water vapor pressure at body temperature.

62
Q

What is the composition of alveolar gas?

A

2.5 to 3 L of gas already in the lungs plus approximately 350 mL of fresh air per breath.

This mixture is essential for effective gas exchange.

63
Q

What happens to the alveolar PO2 and PCO2 during normal tidal breathing?

A

Alveolar PO2 increases by 2 to 4 mm Hg and PCO2 falls by 2 to 4 mm Hg with each inspiration.

This reflects the dynamics of gas exchange in the lungs.

64
Q

What is the relationship between alveolar ventilation and arterial PCO2?

A

If alveolar ventilation is doubled, arterial PCO2 is reduced by half.

This highlights the importance of ventilation in regulating blood gas levels.

65
Q

How does increased alveolar ventilation affect alveolar PO2?

A

As alveolar ventilation increases, alveolar PO2 also increases.

However, it cannot exceed the inspired PO2 of about 149 mm Hg.

66
Q

What happens to alveolar PO2 as alveolar ventilation increases?

A

Alveolar PO2 increases, but it cannot double if already at approximately 104 mm Hg.

The maximum possible alveolar PO2 when breathing air at sea level is about 149 mm Hg.

67
Q

What is the alveolar air equation?

A

PAO2 = PIO2 - PACO2R + F

R is the respiratory exchange ratio and F is a small correction factor.

68
Q

What does the respiratory exchange ratio (R) represent?

A

The whole body carbon dioxide produced per time divided by the whole body oxygen consumption per time.

R is approximately 0.8 for a typical mixed diet, 1.0 for a carbohydrate/protein diet, and 0.7 for a fat diet.

69
Q

How much gas is in the lungs at FRC for a 70-kg person?

A

About 2.5 to 3 L of gas.

Each eupneic breath brings about 350 mL of fresh gas into the alveoli.

70
Q

Which regions of the lungs receive more ventilation per unit volume?

A

Lower regions of the lungs receive more ventilation than upper regions.

This is observed in normal subjects seated upright.

71
Q

What is the effect of gravity on regional alveolar ventilation?

A

Dependent regions are better ventilated than nondependent regions due to gravity.

This is evident when comparing ventilation in subjects seated upright versus lying on their side.

72
Q

What causes the gradient of intrapleural surface pressure in the thorax?

A

Gravity and mechanical interactions between the lung and chest wall.

The intrapleural pressure is less negative in dependent regions than in nondependent regions.

73
Q

What is the transpulmonary pressure?

A

The difference between alveolar pressure and intrapleural pressure.

Greater transpulmonary pressure in upper regions leads to larger alveolar volumes.

74
Q

What is the closing volume in the lungs?

A

The lung volume at which airway closure begins to occur.

It can be demonstrated using a method similar to Fowler’s technique.

75
Q

What occurs during the first expiration to the RV after inhaling 100% oxygen?

A

Gas left in the lungs is about 80% nitrogen, mostly from upper parts of the lung.

Alveoli in lower regions have smaller volumes and contain less nitrogen.

76
Q

What does phase I of the nitrogen concentration trace indicate?

A

Gas from the anatomic dead space, virtually 100% oxygen or 0% nitrogen.

77
Q

What is indicated by a steep slope in phase III of the nitrogen concentration trace?

A

Nonuniform distribution of alveolar gas.

This occurs in patients with airways-resistance maldistribution.

78
Q

Fill in the blank: As alveolar ventilation increases, the alveolar ______ decreases.

A

PCO2

79
Q

True or False: The F factor in the alveolar air equation is always significant.

A

False

The F factor is usually ignored in calculations.

80
Q

What happens to the ventilation of nondependent alveoli at low lung volumes?

A

They receive preferential ventilation due to the intrapleural pressure gradient.

81
Q

What characterizes the alveoli in the upper regions of the lung during normal breathing?

A

They have larger volumes and are less compliant at FRC.

82
Q

What is the effect of positive intrapleural pressures during forced expiration?

A

It leads to dynamic compression of small airways and airway closure.

83
Q

What happens to airway closure during the initial part of an inspiratory effort from RV?

A

Airways in the lower regions are still closed and no air enters until sufficient negative pressure is generated.

84
Q

What is the slope of phase III in a healthy person?

A

Nearly horizontal

In patients with certain types of airways-resistance maldistribution, the phase III slope rises rapidly.

85
Q

What causes the phase III slope to rise rapidly in patients with airways-resistance maldistribution?

A

Alveoli supplied by high-resistance airways fill more slowly during 100% oxygen inspiration.

86
Q

What happens to expired nitrogen concentration during expiration in patients with airways-resistance maldistribution?

A

The expired nitrogen concentration rises due to slower emptying of high-resistance alveoli.

87
Q

What is the closing capacity?

A

RV plus the volume expired between the beginning of airway closure and the RV.

88
Q

What is the difference between closing volume and closing capacity?

A

Closing volume is often used interchangeably with closing capacity, but they are not the same.

89
Q

What happens to airway closure in lower regions of the lung?

A

Airway closure occurs first in lower regions where nitrogen concentration is lowest.

90
Q

What significant changes occur in the respiratory system due to aging?

A

Loss of alveolar elastic recoil, alterations in chest wall structure, decreased respiratory muscle strength, loss of alveolar surface area.

91
Q

What effect does aging have on lung compliance?

A

Increased static lung compliance and decreased chest wall compliance.

92
Q

How does aging affect functional residual capacity (FRC)?

A

FRC usually increases with aging.

93
Q

What is the relationship between alveolar ventilation and minute volume?

A

Alveolar ventilation is less than minute volume due to anatomic dead space.

94
Q

What constitutes alveolar dead space?

A

Ventilated alveoli that are not perfused.

95
Q

What is physiological dead space?

A

The sum of anatomic dead space and alveolar dead space.

96
Q

At constant carbon dioxide production, how is alveolar PCO2 related to ventilation?

A

Alveolar PCO2 is approximately inversely proportional to alveolar ventilation.

97
Q

At or near functional residual capacity, which alveoli are better ventilated?

A

Alveoli in lower regions of the upright lung.

98
Q

Fill in the blank: The closing capacity is equal to _______.

A

RV plus the volume expired between the beginning of airway closure and the RV.

99
Q

True or False: Closing volume and closing capacity are often used interchangeably.

A

True

100
Q

What is the primary impact of kyphoscoliosis on lung function?

A

Decreased compliance of the rib cage, resulting in restrictive lung disease.

101
Q

How does kyphoscoliosis affect the work of breathing?

A

Increases inspiratory work of breathing.

102
Q

What is the typical effect of aging on total lung capacity (TLC)?

A

TLC stays fairly constant when adjusted for decreased height.

103
Q

What are the primary lung volumes that decrease with aging?

A

Expiratory reserve volume (ERV) and maximal expiratory airflow rates.

104
Q

What happens to arterial oxygen tension with aging?

A

Progressive decrease due to loss of alveolar surface area and decreased pulmonary capillary blood volume.

105
Q

What is the effect of aging on pulmonary diffusing capacity?

A

Decreased pulmonary diffusing capacity.

106
Q

What is the effect of changing from supine to upright position on FRC?

A

FRC typically increases.

107
Q

What occurs to RV when a person moves from supine to upright?

A

RV decreases.

108
Q

What is the significance of the FEV1/FVC ratio in restrictive lung disease?

A

It remains normal despite low FEV1 and FVC values.

109
Q

What is the common treatment for patients with kyphoscoliosis?

A

Improving alveolar ventilation, such as with noninvasive mechanical ventilation.

Lange Pulmonary Physiology, 10e (12 decks)

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