Harvey Flashcards

1
Q

Although the diameter of the airways decreases as you get nearer the alveoli…what happens to the cross sectional area?

A

It increases a crazy amount!!

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2
Q

How many generations make up the pulmonary tree? What is a generation?

A

23

A generation is a branching of the airways.

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3
Q

The conducting zone consists of how many generations? What is this space considered? What is the volume of this space?

A

16 generations
150 mL
anatomic dead space (no gas exchange)

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4
Q

The conducting zone ends at what structure?

A

terminal bronchioles

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5
Q

The respiratory zone begins at what structure?

A

respiratory bronchioles

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6
Q

The respiratory zone consists of how many generations? Its functional unit is called what? What is its approximate volume?

A

7 generations
functional unit: acinus
Volume HUGE like 3000mL

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7
Q

What is one way to determine the lung’s functional volumes?

A

spirometer!!

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8
Q

What is the approximate value of the tidal volume?

A

0.5 L

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9
Q

What is the approximate inspiratory capacity volume?

A

2.5 L

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10
Q

What is the approximate expiratory reserve capacity volume?

A

1.5 L

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11
Q

What is the value of the residual volume?

A

1.5 L

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12
Q

What is the vital capacity? What is the volume?

A

If you take a maximal inspiration…it is the maximum amount of volume you can expire from your lungs. Total lung capacity - Residual Volume.
4.5 L

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13
Q

What is the functional residual capacity? What is its approximate volume?

A

After a tidal volume inspiration…the amount of volume left in your lungs.
3L

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14
Q

What is inspiratory capacity? what is its approximate volume?

A

the total amount of air you can inspire
tidal volume + inspiratory reserve capacity
3L

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15
Q

What is the approximate value of total lung capacity?

A

6.0 L

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16
Q

What are the values that you can’t measure w/ spirometry?

A

residual volume
functional residual capacity
total lung capacity

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17
Q

When you are lying down the residual volume decreases. Why?

A

b/c the abdominal contents push up on your diaphragm & allow you to exhale more air.

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18
Q

What are 3 methods for measuring FRC since spirometry doesn’t work?

A

Nitrogen Dilution
Helium Dilution
Plethysmography

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19
Q

What equation is nitrogen dilution based off of?

A

C1V`1=C2V2

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20
Q

What concept is plethysmography based off of?

A

Boyle’s Law

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21
Q

What are the 2 types of inspiration?

A

Positive Pressure Breathing

Negative Pressure Breathing

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22
Q

What is positive pressure breathing & when does it occur?

A

The air on the outside is above atmospheric pressure & the air in the alveolar space is @ atmospheric pressure & then air can flow in b/c of the pressure difference.
**this is used w/ mechanical ventilation in the hospital. You kinda force the air in.

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23
Q

What is negative pressure breathing & when does it occur?

A

This is where you expand the chest cavity to make the intrapleural pressure negative & the air on the outside is @ atmospheric pressure & it can flow in b/c of the pressure difference.
**this is how most of us breathe!!

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24
Q

In a healthy person, what are the most important muscles for inspiration? If the person is healthy–>is inspiration active or passive?

A

diaphragm: contracts & pushes down (expands volume)
external intercostals: pull the ribs upward (expands volume)
Active process

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25
Q

What are the accessory muscles of inspiration & when are these necessary?

A

Scalenes: lift the first 2 ribs
Sternocleidomastoid: raises the sternum
**used during exercise or like in patients w/ COPD

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26
Q

What are the main muscles of expiration in a healthy person? Is this normally an active or passive process?

A

No muscles normally b/c it is usu a passive process.

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27
Q

What happens to expiration when a person is exercising?

A

It becomes an active process & you use accessory muscles.

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28
Q

What are the important muscles of active expiration?

A

abdominal muscles: push cavity inward (rectus abdominis, external & internal obliques, transverses abdominis)
Internal Intercostals: pulls the rib cage down

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29
Q

At the end of tidal expiration, what is the pressure difference b/w the atmosphere & the alveoli?

A

0, therefore no air flow.

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30
Q

At the end of tidal expiration is there a negative pressure anywhere in the lung?

A

Yes, there is a negative intrapleural pressure. Of about -5cmH2O.

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31
Q

What creates the negative intrapleural pressure of the lung at the end of tidal expiration?

A

the combination of the elastic recoil of the lungs “wanting” to go inward & the elastic recoil of the chest wall “wanting” to go outward.

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32
Q

What is the equation for transpulmonary pressure?

A

Transpulmonary Pressure = Alveolar pressure - Intrapleural Pressure

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33
Q

At the end of tidal expiration, what is the transpulmonary pressure?

A

+5 cmH2O

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34
Q

At the end of tidal expiration, what is the volume that is in the lungs?

A

FRC

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35
Q

What is another name for transpulmonary pressure?

A

elastic recoil pressure

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36
Q

What causes a change in lung volumes?

A

changes in transpulmonary pressure

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37
Q

In detail, explain what causes air to flow into the lungs with inspiration.

A

Expand the chest with inspiratory muscles.
Higher chest volume means lower chest pressure (negative w/ respect to the atmosphere).
Now: the alveolar pressure < atmospheric pressure
Intrapleural pressure is even more negative (-8)
The transpulmonary pressure is even more positive (+7)
This allows air to flow in.

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38
Q

Changes in transpulmonary pressure is due to changes in what other 2 pressures?

A

Transrespiratory

Transthoracic

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39
Q

What is the equation for transrespiratory pressure?

A

Transrespiratory Pressure = Alveolar Pressure - Atmospheric Pressure

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40
Q

What is the equation for transthoracic pressure?

A

Transthoracic Pressure = Intrapleural Pressure - Atmospheric Pressure

41
Q

When does the intrapleural pressure finally plateau & become more positive?

A

At the end of inspiration.

42
Q

What does flow correspond w/?

A

it corresponds with alveolar pressure–>they both peak together…

43
Q

When do the alveolar pressure & flow peak together?

A

At the middle of inspiration.

44
Q

Why do the alveolar pressure & flow peak at all?

A

b/c as the chest volume expands air flows in & lowers the volume at the same time. This corresponds to a point in the middle that starts to reverse the inspiration.

45
Q

What is compliance?

A

the change in volume for a given change in pressure

46
Q

What is the significance of the slope in a pressure volume loop?

A

It corresponds to the compliance.

It reflects the elastic nature of the lung.

47
Q

When you have higher compliance, you have less ______.

A

Higher Compliance

Less Elastance

48
Q

B/c the slope of the pressure volume loop changes during inspiration & expiration….what else changes throughout this process?

A

compliance changes…

49
Q

What does emphysema do to the pressure volume loop? Why?

A

It makes the slope steeper. This means that it is more compliant. This is b/c you lose the elasticity of your lung when you have emphysema.

50
Q

What is hysteresis? What is responsible for this?

A

The difference b/w the inspiration & expiration lines of the pressure volume loop.
Surface tension is responsible for this.
Surfactant decreases this effect.

51
Q

The lung is less compliant at high/low volumes. This corresponds to what type of slope?

A

Less compliant @ high lung volumes. Milder slope.

52
Q

Does compliance increase or decrease w/ the following pulmonary diseases:
emphysema
pulmonary fibrosis

A

Emphysema: compliance increases

Pulmonary Fibrosis: compliance decreases

53
Q

What is responsible for the elastic properties of the lungs?

A

Elastin & collagen fibers that surround the bronchi & alveoli

54
Q

When there is no transpulmonary pressure gradient…what is the volume in the lung?

A

not zero…

55
Q

What is surface tension? What increases it?

A

the attractive forces b/w molecules

an air-liquid interface increases it.

56
Q

What happened to the pressure volume loop when the lung was inflated w/ saline solution?

A

Its slope became steeper & the hysteresis disappeared.
This is b/c w/ saline soln there is no surface tension.
Thus, compliance increases (steeper slope) & no hysteresis (caused by surface tension).

57
Q

What does surfactant do to the pressure volume loop?

A
It reduces surface tension.
Steeper Slope
Higher Compliance
Lower elastance
Lower surface tension
Less Hysteresis
58
Q

Which has a greater surface tension & pressure: a small alveolus or a large alveolus?

A

a small alveolus

59
Q

Without surfactant, what happens to the small alveoli?

A

the greater pressure in the small alveoli causes the air to flow out of them into the larger alveoli. The small alveoli collapse.
Surfactant reduces surface tension & keeps this from happening.

60
Q

What size of alveoli does surfactant have a greater effect on?

A

small alveoli–>greater effect!!

61
Q

What cells secrete surfactant?

A

Type II alveolar cells or Type II pneumocytes

62
Q

What is the main component of surfactant? What is its nature?

A

DPPC: dipalmitoyl phosphatidylcholine

amphipathic

63
Q

What are 2 diseases that involve a lack of surfactant?

A

Infant Respiratory Distress Syndrome

Acute Respiratory Distress Syndrome

64
Q

What is infant respiratory distress syndrome?

A

born premature w/o surfactant.

Surfactant doesn’t develop until 4 month of gestation, & isn’t fully functional until the 7th month.

65
Q

What is acute respiratory distress syndrome?

A

a lack of surfactant due to hypoxia or hypoxemia.

66
Q

What happens to you when you lack surfactant?

A

Decreased Compliance
Increased tendency of the alveoli to collapse
Harder to breathe!! Poor thing…

67
Q

What happens to intrapleural pressure & the size of the lung & chest wall w/ a pneumothorax?

A

Lung is punctured & pressures everywhere (including the intrapleural pressure) equalize w/ the atmospheric pressure.
The lung & chest wall can no longer balance each other out so the lungs collapse & the chest wall expands.

68
Q

What determines functional residual capacity?

A

a balance b/w outward elastic recoil of the chest wall & the inward elastic recoil of the lungs…

69
Q

Which has the lowest compliance?
Lung
Chest Wall
Lung + Chest wall (working together)

A

Lung & Chest Wall (working together)
least steep slope
most elastic

70
Q

What does emphysema do to compliance? Elasticity? FRC?

A

Compliance increases (more steep)
Elasticity decreases
FRC higher

71
Q

What does fibrosis do to compliance? Elasticity? FRC?

A

Compliance decreases (less steep)
Elasticity increases
FRC lower

72
Q

b/c of gravity…there is difference in the intrapleural pressure at the base of the lung vs. at the apex of the lung…Where is the pressure the least negative?

A

Base of the lung.

73
Q

Where in the lung are the alveoli the most compressed?

A

near the base of the lung…

74
Q

Is the slope steeper at the base of the lung or the apex of the lung? What does this mean for compliance?

A

Steeper at the base of the lung.

Higher compliance here.

75
Q

Where is there more ventilation of the lung? At the base or the apex?

A

At the base of the lung.

76
Q

If you are operating at lower lung volumes…how does that change the distribution of compliance?

A

In this case…the base of the lung is less compliant than the apex of the lung.

77
Q

What are the 2 main sources of resistance to airflow in the lungs?

A

Elastic Resistance
Non-elastic resistance
**mainly elastic

78
Q

What are the 2 sources of non-elastic resistance in the lung?

A

Airflow

Viscosity (friction b/w the lungs & the chest wall)

79
Q

What are the 2 types of airflow?

A

Laminar & Turbulent

80
Q

What are the characteristics of laminar flow?

A

faster in the middle & slower on the sides. peaceful flow…like down a river : )

81
Q

What are the characteristics of turbulent flow?

A

just crazy chaos & churning…like kayaking down some rapids…makes it hard to get air out of the lungs.

82
Q

What has the greatest effect on airflow, according to Poiseuille’s Law?

A

the radius of the airway…fourfold difference…

83
Q

What is the purpose of the Reynold’s Number?

A

the higher the Reynold’s number the more likely the flow will be turbulent.
Re=2rvd/n

84
Q

Describe the 3 conditions that usu cause turbulent flow.

A

High velocity of airflow
Large radius of airway
Dense gas being inhaled

85
Q

Where is turbulent flow most likely to occur?

A

trachea during exercise

86
Q

Where is laminar flow most likely to occur?

A

terminal bronchioles

87
Q

Where does airway resistance peak? Where is it lowest?

A

It peaks at the medium-sized bronchioles.
It is lowest @ the terminal bronchioles.
**even tho the radius is lowest, the cross sectional area is the highest & the resistance is therefore the lowest…

88
Q

Breathing at high lung volume causes high/low resistance to airflow?

A

Low resistance–this is why people w/ certain pulmonary diseases compensate by breathing large volumes.

89
Q

What does sympathetic stimulation of the lung do to airway resistance?

A

it decreases it b/c of beta 2 stimulation (dilation)

90
Q

What does parasympathetic stimulation of the lung do to airway resistance?

A

It increases it b/c of the muscarinic receptors & constriction

91
Q

What do inflammatory mediators such as leukotrienes & histamine do to resistance?

A

They increase it. These are the things that are released during an asthma attack.

92
Q

T/F Respiratory effort can affect the resistance to airflow.

A

TRUE

93
Q

What is the difference b/w respiratory effort on inspiration & expiration?

A

Inspiration: increase your effort–>increase your flow
Expiration: increase your effort–>nothing special will happen to your flow. : (
**the expiratory flow rate is constant

94
Q
What's the deal w/ the following during pre-inspiration:
intrapleural pressure
alveolar pressure
transpulmonary pressure
transpulmonary pressure gradient
A

intrapleural pressure: negative (-5)
alveolar pressure: =atmospheric (uniform)
transpulmonary pressure: positive (+5)
transpulmonary pressure gradient: uniform

95
Q
What's the deal w/ the following during inspiration:
intrapleural pressure
alveolar pressure
transpulmonary pressure
transpulmonary pressure gradient
A

intrapleural pressure: more negative (-7)
alveolar pressure: negative (less negative more near the mouth)
transpulmonary pressure: not uniform (more positive closer to the mouth)
transpulmonary pressure gradient: not uniform

96
Q
What's the deal w/ the following during pre-expiration:
intrapleural pressure
alveolar pressure
transpulmonary pressure
transpulmonary pressure gradient
A

intrapleural pressure: quite negative (-8)
alveolar pressure: = atmospheric
transpulmonary pressure: positive (+8)
transpulmonary pressure gradient: uniform again!!

97
Q
What's the deal w/ the following during forced expiration:
intrapleural pressure
alveolar pressure
transpulmonary pressure
transpulmonary pressure gradient
A

intrapleural pressure: super positive (+30)
alveolar pressure: very positive–gradient will less positive towards the mouth
transpulmonary pressure: dramatic
transpulmonary pressure gradient: can become negative as you move toward the mouth

98
Q

What happens when the transpulmonary pressure becomes negative in forced expiration?

A

constriction of airways (small diameter & huge resistance)

**the harder you try the more likely your airways are to collapse…. : (

99
Q

In patients with emphysema they have reduced _____ & this compromises their _____ pressure. Thus, they don’t have trouble w/ inspiration, but only expiration. To combat this you use what technique?

A

reduced elasticity
transpulmonary pressure (less recoil)
Pursed lips increase resistance of the airway & allow them to breathe out their air.