L20: Respiratory System I Flashcards
1
Q
Fick’s law of diffusion
A
rate of diffusion = k * A * (P2-P1)/D
2
Q
rate of diffusion depends on
A
solubility of gas, temperature, surface area, difference in partial pressures, thickness of the barrier
3
Q
pulmonary ventilation
A
movement of air into and out of the lungs
4
Q
movement into lungs
A
inspiration
5
Q
movement out of lungs
A
expiration
6
Q
pulmonary ventilation is done by
A
bulk flow
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
8
Q
upper airways include
A
nasal cavity, oral cavity, pharynx
9
Q
pharynx
A
muscular tube that serves as a common passageway for both air and food
10
Q
esophagus
A
muscular tube leading to the stomach
11
Q
larynx
A
part of respiratory tract, a tube held open by cartilage in its walls
12
Q
what structure contains vocal cords?
A
larynx
13
Q
respiratory tract is divided into
A
conducting and respiratory zone
14
Q
conducting zone
A
conducts air from the larynx to the lungs
15
Q
respiratory zone
A
contains the sites of gas exchange within the lungs
16
Q
the primary difference between conducting and respiratory zones
A
thickness of the walls of the airspaces
17
Q
what air spaces can participate in gas exchange
A
only air spaces with sufficiently thin walls
18
Q
larynx opens into
A
trachea
19
Q
trachea opens into
A
two bronchi
20
Q
right bronchus divides into
A
three secondary bronchi
21
Q
left bronchus divides into
A
two secondary bronchi
22
Q
within the lungs, there are more than ___ generations of branchings
A
20
23
Q
major sites of gas exchange
A
alveoli
24
Q
branching sequence
A
trachea – bronchi – bronchioles – terminal bronchioles –respiratory bronchioles – alveolar ducts – alveolar sacs
25
where do alveoli start to appear?
respiratory bronchioles
26
what structure entirely consists of alveoli?
alveolar sacs
27
alveolar sac is surrounded by
elastic fibers and network of capillaries
28
how many bronchioles are there?
80 million
29
air-facing surface of alveolar wall is lined by
type I alveolar cells
30
type I alveolar cells
flat epithelial cells
31
type I alveolar cells function
gas exchange
32
type II alveolar cells function
synthesis of the surfactant
33
each lung is surrounded by
pleural sac and chest wall
34
pleural sac
double membrane surrounding each lung, one membrane lines lungs, the other lines chest wall
35
pleural sac is similar to
fluid-filled balloon around air-filled balloon
36
ventilation occurs because of
the presence of pressure gradients between the alveoli and the outside air
37
air moves ___ a pressure gradient
down
38
inspiration occurs when the pressure in the alveoli is ___ than the pressure in the atmosphere
lower
39
expiration occurs when the pressure in the alveoli is ____ than the pressure in the atmosphere
higher
40
four primary pressures associated with ventilation
atmospheric pressure, intra-alveolar pressure, intra-plural pressure, transpulmonary pressure
41
atmospheric pressure value
760 mm Hg at sea level
42
atmospheric pressure ___ as altitude increases
decreases
43
atmospheric pressure ___ under the water
increases
44
for our purposes we treat atmospheric pressure
as constant and equal to zero
45
atmospheric pressure
pressure of outside air
46
intra-alveolar pressure
pressure of air in alveoli
47
intra-alveolar pressure value
varies with phase of respiration
48
intra-alveolar pressure during inspiration
negative/less than atmospheric
49
intra-alveolar pressure during expiration
positive/more than atmospheric
50
intra-alveolar pressure at rest
zero/equal to atmospheric
51
what drives ventilation?
difference between atmospheric and intra-alveolar pressure
52
intra-pleural pressure
pressure inside the pleural sac
53
intrapleural pressure value
always negative, always less than Palv, varies with phase of respiration
54
intrapleural pressure at rest
around 4 mm Hg
55
why is intrapleural pressure negative?
due to elasticity in lungs and chest wall
56
in what direction do lungs and chest wall pull
opposing, lungs recoil inward, while chest recoils outward
57
what holds lungs and chest wall together?
surface tension
58
to maintain negative intrapleural pressure ___
the pleural sac must be airtight
59
if the pleural sac is broken ___
the negative intrapleural pressure is lost as it equilibrates with atmospheric pressure
60
without negative P(ip) ___
the lungs recoil and collapse, while the chest wall recoils and expands
61
how does the condition when P(ip) is lost called?
pneumothorax
62
transpulmonary pressure
distending (expanding) pressure across the lung wall
63
transpulmonary pressure
P(alv) - P(ip)
64
an increase in transpulmonary pressure creates __
a larger distending pressure across lungs
65
a larger distending pressure across lungs causes ___
lungs expand and increase the volume
66
pressure gradients are created
by changing the volume of the lungs
67
Boyle's law
pressure is inversely related to volume
68
intra-alveolar pressure is determined by
the quantity of air in alveoli and the volume of alveoli
69
inspiration 1: at the start of inspiration ___
the lungs expand as a result of contraction of the inspiratory muscles
70
inspiration 1: the expansion of alveolar volume ___
lowers P(alv); P(alv) < P(atm); air drawn into the lungs
71
inspiration 2: P(alv) rises as ____
the number of air molecules flow in
72
rest: when P(alv) = P(atm), ___
air stops flowing inward
73
expiration 1: as the lung volume decreases, __
P(alv) increases and air flows out
74
expiration 2: P(alv) lowers as ___
the number of air molecules flow out
75
inspiration is initiated by
neural stimulation of inspiratory muscles – ACh is released at the NMJ
76
what causes lungs to flatten and move downward?
contraction of the diaphragm
77
what causes the ribs to pivot upward and outward?
contraction of the external intercostal muscles
78
what does pivoting ribs do?
expand the chest wall
79
as chest wall expands, ____
its pulls outward on the intrapleural fluid, causing P(ip) to decrease
80
decrease of P(ip) causes transpulmonary pressure to ___
increase
81
increase in transpulmonary pressure leads to
larger distending pressure across the lungs and lungs start expanding
82
when alveoli expand,
P(alv) < P(atm), so air flows into the alveoli by bulk flow
83
during quiet breathing, ____
expiration is normally a passive process and does not require muscle contraction
84
when motor neurons to inspiratory muscles stop firing, ___
inspiratory muscles relax
85
when inspiratory muscles relax, ___
lungs and chest wall recoil to original positions
86
volume of cavity thoracic decreases, causing ___
P(alv) > P(atm)
87
air flows out until ___
P(alv) = P(atm)
88
what factors affect pulmonary ventilation?
lung compliance and airway resistance
89
compliance
measure of the ease with which lung can be stretched
90
what factors affect lung compliance?
elasticity and surface tension
91
lung lobes
superior, middle and inferior
92
airway resistance
resistance of the airways in the respiratory tract
93
lung compliance formula
lung compliance = delta(V)/delta(P)
94
having larger lung compliance is
advantageous
95
larger lung compliance is better because
a smaller change in transpulmonary pressure is needed, so less work or muscle contraction is required
96
lungs are elastic because of ___
the presence of elastic connective tissue fibers
97
forces by elastic fibers ___ lung expansion
oppose
98
emphysema
destruction of elastin fibers found in lung tissue
99
surface tension of a liquid
work required to increase its surface area by a certain amount
100
the greater the surface tension, ___ work needed to spread the fluid out
the more
101
surface tension of lungs is created by
the air liquid interface formed by the thin layer of fluid lining the alveoli
102
as lung expands, work is required to
stretch the elastic tissue and increase the surface area of the fluid layer
103
greater surface tension lead ____ compliance
lower
104
Laplace's law
P = 2T / r
105
what decreases the surface tension in alveoli?
pulmonary surfactant
106
surfactant is secreted from
type II alveolar cells
107
how does surfactant decrease the surface tension?
by interfering with hydrogen bonding between water molecules
108
surfactant stabilizes alveoli of different size by
differentially altering surface tension
109
prematurely born babies can develop
newborn distress syndrome (NRDS)
110
too little surfactant causes
stiff, low compliance lungs, allows alveoli collapse and re-inflate
111
treatment for NRDS
administration of steroid hormones to increase surfactant production, aerosol administration of artificial surfactant, artificial ventilation
112
lung compliance is determined by
the elastic connective tissues of the lungs and the surface tension of the fluid lining the alveoli
113
surface tension is greatly reduced and compliance increased by
surfactant
114
airway resistance determines
how much air flows into the lungs at any given pressure different between atmosphere and alveoli
115
major determinant of airway resistance
the radii of the airways
116
four primary pressures associated with ventilation are
atmospheric pressure, intra-alveolar pressure, intra-plural pressure, transpulmonary pressure
117
inspiration and expiration are driven by
differences in atmospheric and intra-alveolar pressures
118
pressure gradients in lungs are created when
the volume of the lungs is changed
119
inspiration is caused by
the contraction of the diaphragm and the external intercostal muslces
120
active expiration involves
contraction of internal intercostals and abdominal muscles
