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BIOL 336 > L20: Respiratory System I > Flashcards

L20: Respiratory System I Flashcards

1
Q

Fick’s law of diffusion

A

rate of diffusion = k * A * (P2-P1)/D

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2
Q

rate of diffusion depends on

A

solubility of gas, temperature, surface area, difference in partial pressures, thickness of the barrier

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3
Q

pulmonary ventilation

A

movement of air into and out of the lungs

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4
Q

movement into lungs

A

inspiration

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5
Q

movement out of lungs

A

expiration

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6
Q

pulmonary ventilation is done by

A

bulk flow

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7
Q

respiratory functions

A

pulmonary ventilation, exchange between lung air and blood by diffusion, transportation of O2 and CO2, exchange between body tissues and blood

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8
Q

upper airways include

A

nasal cavity, oral cavity, pharynx

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9
Q

pharynx

A

muscular tube that serves as a common passageway for both air and food

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10
Q

esophagus

A

muscular tube leading to the stomach

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11
Q

larynx

A

part of respiratory tract, a tube held open by cartilage in its walls

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12
Q

what structure contains vocal cords?

A

larynx

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13
Q

respiratory tract is divided into

A

conducting and respiratory zone

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14
Q

conducting zone

A

conducts air from the larynx to the lungs

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15
Q

respiratory zone

A

contains the sites of gas exchange within the lungs

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16
Q

the primary difference between conducting and respiratory zones

A

thickness of the walls of the airspaces

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17
Q

what air spaces can participate in gas exchange

A

only air spaces with sufficiently thin walls

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18
Q

larynx opens into

A

trachea

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19
Q

trachea opens into

A

two bronchi

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20
Q

right bronchus divides into

A

three secondary bronchi

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21
Q

left bronchus divides into

A

two secondary bronchi

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22
Q

within the lungs, there are more than ___ generations of branchings

A

20

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23
Q

major sites of gas exchange

A

alveoli

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24
Q

branching sequence

A

trachea – bronchi – bronchioles – terminal bronchioles –respiratory bronchioles – alveolar ducts – alveolar sacs

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25
Q

where do alveoli start to appear?

A

respiratory bronchioles

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26
Q

what structure entirely consists of alveoli?

A

alveolar sacs

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27
Q

alveolar sac is surrounded by

A

elastic fibers and network of capillaries

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28
Q

how many bronchioles are there?

A

80 million

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29
Q

air-facing surface of alveolar wall is lined by

A

type I alveolar cells

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30
Q

type I alveolar cells

A

flat epithelial cells

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31
Q

type I alveolar cells function

A

gas exchange

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32
Q

type II alveolar cells function

A

synthesis of the surfactant

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33
Q

each lung is surrounded by

A

pleural sac and chest wall

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34
Q

pleural sac

A

double membrane surrounding each lung, one membrane lines lungs, the other lines chest wall

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35
Q

pleural sac is similar to

A

fluid-filled balloon around air-filled balloon

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36
Q

ventilation occurs because of

A

the presence of pressure gradients between the alveoli and the outside air

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37
Q

air moves ___ a pressure gradient

A

down

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38
Q

inspiration occurs when the pressure in the alveoli is ___ than the pressure in the atmosphere

A

lower

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39
Q

expiration occurs when the pressure in the alveoli is ____ than the pressure in the atmosphere

A

higher

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40
Q

four primary pressures associated with ventilation

A

atmospheric pressure, intra-alveolar pressure, intra-plural pressure, transpulmonary pressure

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41
Q

atmospheric pressure value

A

760 mm Hg at sea level

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42
Q

atmospheric pressure ___ as altitude increases

A

decreases

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43
Q

atmospheric pressure ___ under the water

A

increases

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44
Q

for our purposes we treat atmospheric pressure

A

as constant and equal to zero

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45
Q

atmospheric pressure

A

pressure of outside air

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46
Q

intra-alveolar pressure

A

pressure of air in alveoli

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47
Q

intra-alveolar pressure value

A

varies with phase of respiration

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48
Q

intra-alveolar pressure during inspiration

A

negative/less than atmospheric

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49
Q

intra-alveolar pressure during expiration

A

positive/more than atmospheric

50
Q

intra-alveolar pressure at rest

A

zero/equal to atmospheric

51
Q

what drives ventilation?

A

difference between atmospheric and intra-alveolar pressure

52
Q

intra-pleural pressure

A

pressure inside the pleural sac

53
Q

intrapleural pressure value

A

always negative, always less than Palv, varies with phase of respiration

54
Q

intrapleural pressure at rest

A

around 4 mm Hg

55
Q

why is intrapleural pressure negative?

A

due to elasticity in lungs and chest wall

56
Q

in what direction do lungs and chest wall pull

A

opposing, lungs recoil inward, while chest recoils outward

57
Q

what holds lungs and chest wall together?

A

surface tension

58
Q

to maintain negative intrapleural pressure ___

A

the pleural sac must be airtight

59
Q

if the pleural sac is broken ___

A

the negative intrapleural pressure is lost as it equilibrates with atmospheric pressure

60
Q

without negative P(ip) ___

A

the lungs recoil and collapse, while the chest wall recoils and expands

61
Q

how does the condition when P(ip) is lost called?

A

pneumothorax

62
Q

transpulmonary pressure

A

distending (expanding) pressure across the lung wall

63
Q

transpulmonary pressure

A

P(alv) - P(ip)

64
Q

an increase in transpulmonary pressure creates __

A

a larger distending pressure across lungs

65
Q

a larger distending pressure across lungs causes ___

A

lungs expand and increase the volume

66
Q

pressure gradients are created

A

by changing the volume of the lungs

67
Q

Boyle’s law

A

pressure is inversely related to volume

68
Q

intra-alveolar pressure is determined by

A

the quantity of air in alveoli and the volume of alveoli

69
Q

inspiration 1: at the start of inspiration ___

A

the lungs expand as a result of contraction of the inspiratory muscles

70
Q

inspiration 1: the expansion of alveolar volume ___

A

lowers P(alv); P(alv) < P(atm); air drawn into the lungs

71
Q

inspiration 2: P(alv) rises as ____

A

the number of air molecules flow in

72
Q

rest: when P(alv) = P(atm), ___

A

air stops flowing inward

73
Q

expiration 1: as the lung volume decreases, __

A

P(alv) increases and air flows out

74
Q

expiration 2: P(alv) lowers as ___

A

the number of air molecules flow out

75
Q

inspiration is initiated by

A

neural stimulation of inspiratory muscles – ACh is released at the NMJ

76
Q

what causes lungs to flatten and move downward?

A

contraction of the diaphragm

77
Q

what causes the ribs to pivot upward and outward?

A

contraction of the external intercostal muscles

78
Q

what does pivoting ribs do?

A

expand the chest wall

79
Q

as chest wall expands, ____

A

its pulls outward on the intrapleural fluid, causing P(ip) to decrease

80
Q

decrease of P(ip) causes transpulmonary pressure to ___

A

increase

81
Q

increase in transpulmonary pressure leads to

A

larger distending pressure across the lungs and lungs start expanding

82
Q

when alveoli expand,

A

P(alv) < P(atm), so air flows into the alveoli by bulk flow

83
Q

during quiet breathing, ____

A

expiration is normally a passive process and does not require muscle contraction

84
Q

when motor neurons to inspiratory muscles stop firing, ___

A

inspiratory muscles relax

85
Q

when inspiratory muscles relax, ___

A

lungs and chest wall recoil to original positions

86
Q

volume of cavity thoracic decreases, causing ___

A

P(alv) > P(atm)

87
Q

air flows out until ___

A

P(alv) = P(atm)

88
Q

what factors affect pulmonary ventilation?

A

lung compliance and airway resistance

89
Q

compliance

A

measure of the ease with which lung can be stretched

90
Q

what factors affect lung compliance?

A

elasticity and surface tension

91
Q

lung lobes

A

superior, middle and inferior

92
Q

airway resistance

A

resistance of the airways in the respiratory tract

93
Q

lung compliance formula

A

lung compliance = delta(V)/delta(P)

94
Q

having larger lung compliance is

A

advantageous

95
Q

larger lung compliance is better because

A

a smaller change in transpulmonary pressure is needed, so less work or muscle contraction is required

96
Q

lungs are elastic because of ___

A

the presence of elastic connective tissue fibers

97
Q

forces by elastic fibers ___ lung expansion

A

oppose

98
Q

emphysema

A

destruction of elastin fibers found in lung tissue

99
Q

surface tension of a liquid

A

work required to increase its surface area by a certain amount

100
Q

the greater the surface tension, ___ work needed to spread the fluid out

A

the more

101
Q

surface tension of lungs is created by

A

the air liquid interface formed by the thin layer of fluid lining the alveoli

102
Q

as lung expands, work is required to

A

stretch the elastic tissue and increase the surface area of the fluid layer

103
Q

greater surface tension lead ____ compliance

A

lower

104
Q

Laplace’s law

A

P = 2T / r

105
Q

what decreases the surface tension in alveoli?

A

pulmonary surfactant

106
Q

surfactant is secreted from

A

type II alveolar cells

107
Q

how does surfactant decrease the surface tension?

A

by interfering with hydrogen bonding between water molecules

108
Q

surfactant stabilizes alveoli of different size by

A

differentially altering surface tension

109
Q

prematurely born babies can develop

A

newborn distress syndrome (NRDS)

110
Q

too little surfactant causes

A

stiff, low compliance lungs, allows alveoli collapse and re-inflate

111
Q

treatment for NRDS

A

administration of steroid hormones to increase surfactant production, aerosol administration of artificial surfactant, artificial ventilation

112
Q

lung compliance is determined by

A

the elastic connective tissues of the lungs and the surface tension of the fluid lining the alveoli

113
Q

surface tension is greatly reduced and compliance increased by

A

surfactant

114
Q

airway resistance determines

A

how much air flows into the lungs at any given pressure different between atmosphere and alveoli

115
Q

major determinant of airway resistance

A

the radii of the airways

116
Q

four primary pressures associated with ventilation are

A

atmospheric pressure, intra-alveolar pressure, intra-plural pressure, transpulmonary pressure

117
Q

inspiration and expiration are driven by

A

differences in atmospheric and intra-alveolar pressures

118
Q

pressure gradients in lungs are created when

A

the volume of the lungs is changed

119
Q

inspiration is caused by

A

the contraction of the diaphragm and the external intercostal muslces

120
Q

active expiration involves

A

contraction of internal intercostals and abdominal muscles

BIOL 336 (20 decks)

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