84 - 166 Flashcards
1
Q
look at slide 84 images
A
thumbs up
2
Q
Tracheal Histology:
Four layers (exterior to lumen)?
A
- Adventitia
- Hyaline cartilage
- Submucosa
- Mucosa
3
Q
Usually 16-20 incomplete, horizontal rings stacked on one another (resemble letter “C”)
A
Hyaline cartilage of the trachea
4
Q
Opening is to the posterior, facing the esophagus
A
Horizontal rings of Hyaline cartilage of the trachea
5
Q
Hyaline cartilage of the trachea:
______ membrane spans this opening
Inside this membrane lie transverse smooth muscle fibers called the ______
Membrane also contains elastic connective tissue that allows…
A
Fibromuscular
trachealis muscle
…. the diameter to change during inhalation/exhalation
6
Q
Semi-rigid structure allows for patency of the airway so that it does not collapse on itself
A
Hyaline cartilage of the trachea
7
Q
Areolar connective tissue
Contains seromucous glands and their ducts
A
Submucosa of the trachea
8
Q
which layer of the trachea Contains seromucous glands and their ducts?
what type of tissue is found here?
A
Submucosa of the trachea
Areolar connective tissue
9
Q
Contains pseudostratified ciliated columnar epithelium (like nasal cavity and larynx)
Provides protection from dust, other particles
A
Mucosa layer of trachea
10
Q
Mucosa layer of trachea:
Contains __ ___ ___ epithelium (like nasal cavity and larynx)
A
pseudostratified ciliated columnar
11
Q
The image on slide 87 is vital to your performance on the next exam, but MORE IMPORTANTLY to your understanding of the respiratory system as a provider
A
Gut check
12
Q
At superior border of ____ ____ ____, trachea divides into
Right primary (main) bronchus
- –Shorter, more vertical, and wider than left
- –Why is this important?
Left primary (main) bronchus
A
5th thoracic vertebra
more vertical and wider = more of a potential of a right main stem
13
Q
Considered to be most sensitive area for the cough reflex
A
Carina- the point where the trachea divides
14
Q
the point where the trachea divides
A
Carina
15
Q
The ___ carry air into the lungs
A
bronchi
16
Q
Bronchi contain incomplete rings of ____ ____
Bronchi are also lined with pseudostratified ciliated columnar epithelium (like trachea, nasal cavity)… what does this help to do?
A
hyaline cartilage
Helps to remove foreign objects (dust, etc)
17
Q
Bronchial Tree Flow
Talk me through it from Primary Bronchus to smallest bronchi (not bronchioles)… siri is listening
A
Primary (main) bronchus TWO (1:1)
Secondary (lobar) bronchus FIVE (3:2)
- —-3 in right lung
- —-2 in left lung
Tertiary (segmental) bronchus TWENTY (10:10)
—–10 segments in each lung
Transition to smaller and smaller bronchi
—–Until lumen is ~1mm and no cartilage in airway walls, which signifies the transition to bronchioles
SLIDE 96 may be a good picture for reinforcement
18
Q
Bronchial Tree Flow
Talk me through it from Lobular bronchioles to to alveoli… siri is still listening
A
Lobular bronchioles
Terminal bronchioles
- –Last part of conducting zone
- –Last MACROSCOPIC airway
Respiratory bronchioles
- –First part of respiratory zone
- –First MICROSCOPIC airway
Alveolar ducts
Alveolar sacs
—Group of alveoli sharing same alveolar duct
Alveolus (Alveoli)
19
Q
—Last part of conducting zone
—Last MACROSCOPIC airway
A
Terminal bronchioles
20
Q
—First part of respiratory zone
—First MICROSCOPIC airway
A
Respiratory bronchioles
21
Q
Cartilage In Resp System
Cartilage
—As bronchi transition into smaller branches, rings of cartilage are….
—As bronchi divide into smaller bronchi (tertiary and smaller), these plates get much ____
- –As cartilage reduces in size and quantity, amount of smooth muscle increases
- ——— _____ have complete smooth muscle with NO cartilage
A
…replaced by plates of cartilage
smaller
Bronchioles
22
Q
As _____ reduces in size and quantity, amount of smooth muscle increases
A
cartilage of the respiratory system
23
Q
Terminal bronchioles:
Represent ______ of respiratory system
Have _____ function
A
Represent END of conducting zone of respiratory system
Have exocrine function
24
Q
Terminal bronchioles
Have exocrine function:
contain ___ cells which are?
they protect against?
produce what?
Function as what type of cell?
A
Contain club cells (formerly known as Clara cells)
Non-ciliated cells interspersed among epithelial cells
Protects against harmful toxins and carcinogens
Produces/secretes small amount of surfactant (liquid/mucous)
—–This surfactant acts to help keep the bronchiole lumen from collapsing onto itself and remaining closed
Function as stem cells (reserve cells)
—–Gives rise to various cells in epithelium
25
Contain club cells (formerly known as Clara cells)
--Non-ciliated cells interspersed among epithelial cells
--Protects against harmful toxins and carcinogens
- -Produces/secretes small amount of surfactant (liquid/mucous)
- ----This surfactant acts to help keep the bronchiole lumen from collapsing onto itself and remaining closed
- -Function as stem cells (reserve cells)
- ----Gives rise to various cells in epithelium
Terminal bronchioles
look at image on slide 99
26
Bronchioles and Innervation:
Bronchioles – ANS
Sympathetic stimulation – (exercise)
Causes release of norepinephrine from adrenal medulla which bind to....
This binding leads to these two things?
This improved ventilation allows for more oxygen to be delivered to muscle tissues in the body... T or F?
....beta-adrenergic receptors in the smooth muscle of the airways
1. Causes bronchodilation (relaxation of smooth muscle in airways)
2. Increases cilia beat frequency (removes more mucous)
True
27
Bronchioles and Innervation:
Bronchioles – ANS
Parasympathetic stimulation - (rest)
What does Ach bind to and where?
Acetylcholine (Ach) binds to muscarinic receptors in smooth muscle of airways
28
Bronchioles – ANS
Parasympathetic stimulation - (rest)
What does the binding of Ach cause in regards to smooth muscle tissue and mucous?
Causes slight contraction of smooth muscle surrounding the bronchioles (bronchoconstriction)
Causes increase in mucous production
29
A physiologic constriction that only slightly reduces the amount of ventilation occurring
If at rest, most people don’t require constant, total ventilation throughout the lungs
bronchoconstriction
30
In term of receptors of bronchioles... there are more adrenergic receptors than cholinergic receptors (T or F)?
NO!!!
Many more cholinergic receptors found in pulmonary smooth muscle tissue than compared to adrenergic
31
Lung Anatomy
Paired, cone shaped organs in thoracic cavity
```
Separated by the mediastinum
§ Heart
§ Aorta
§ Thymus gland
§ Chest portion of trachea
§ Esophagus
§ Lymph nodes
§ Nerves
```
As a result, two distinct cavities exist (pleuralcavities)
104
32
Each lung is enclosed and protected by a double
| layered serous membrane called the
pleural membrane
33
– superficial membrane lining the wall
| of the thoracic cavity
Parietal pleura
34
– deep layer that covers the lungs
| themselves
Visceral pleural
35
– small space between the pleural layers containing small amount of lubricating fluid
Pleural cavity
36
Fluid allows for smooth movement of pleura during
breathing
~8-10mL of fluid
Pleural cavity
37
Pleural fluid
§ Usually 8-10mL in cavity space
§ Thought that over 100mL per hour is made at parietal layer and drained at the
visceral layer and lymphatics
38
Helps the two pleural layers “adhere” to each other
§ Still allowing sliding motion to occur during inhalation/exhalation
Pleural fluid
39
Pleural fluid
§ Think of water between two microscope slides
§ Adhere to each other but can still slide
§ This is called ____ and becomes a very
important aspect of breathing
surface tension
40
§ This allows the lung to
| “collapse”
Shows normal parietal and visceral pleura
§ Entrance of the scope into this pleural space removes the surface tension between the two layers
41
§ Adhesions are when membranes grow together
§ These two membranes cannot separate unless they are torn apart
Shows pleural cavity space with adhesions
42
Three lobes
§ Superior lobe (3 segments)
§ Middle lobe (2 segments)
§ Inferior lobe (5 segment)
Right Lung
43
Two lobes
§ Superior lobe (5 segments)
§ Inferior lobe (5 segments)
Left lung –
44
Primary Bronchus #'s
Secondary Bronchi
Tertiary
(R to L)
Primary bronchus
(1:1)
§Secondary (lobar) bronchi
(3:2)
§Tertiary (segmental) bronchi
(10:10)
(Right:Left)
45
Lung Anatomy
§ Extend from diaphragm to
just above the level of the clavicles
46
Lung Anatomy
§ Apex of lung protrudes into
supraclavicular space
47
Apex of lung
§ This is the only place to ___
§ Base fits over convex area of...
“palpate” the lungs
...diaphragm
48
Lung Anatomy
§ Right lung is ___ and ___ but ____
§ Right lung is thicker and broader but shorter
49
Lung Anatomy
§ Right lung is thicker and broader but shorter
§ This is due to....
...higher diaphragm accommodating the
| liver
50
Lung Anatomy
§ Left lung is __ and ___ compared to right
thinner and slightly smaller
51
Lung Anatomy
Left lung is thinner and slightly smaller
§ Usually 10% smaller because of
cardiac notch
52
medial projection of inferior aspect of superior
| left lobe
Lingula
53
is the inferior aspect of the cardiac notch
Lingula
54
great pic of lingual and cardiac notch on slide 115
115
55
§ Anterior portion of lungs that lie against ribs
Costal
56
Mediastinal area contains the ___
| where bronchi, vessels, nerves, lymph travel into/out of lungs
hilus
57
(where bronchi, vessels, nerves, lymph travel into/out of lungs)
hilus
58
Mediastinal
Left lung has a _____ which houses the apex
of the heart
cardiac notch
59
§ Inferior aspect (base) of lungs that fits convexity of
| diaphragm
Diaphragmatic
60
§ Inferior aspect (base) of lungs that fits convexity of
| diaphragm
Diaphragmatic
61
Separated by an oblique (major) fissure
Left Lung
| § Two lobes (superior and inferior)
62
§ Three lobes (superior, middle, inferior)
Right lung
63
Right lung
§ _____ – separates mostly inferior and
middle lobes, and then small portion of lateral aspect of
superior and inferior lobes
Oblique (major) fissure
64
Right lung
§ _____ – separates superior and
middle lobes
Horizontal (minor) fissure
65
Middle lobe is much
smaller
66
Look at pics on slide 118 and 119
118 and 119
67
§ Segment of lung tissue supplied by one tertiary
| bronchus (10 in each lung)
Bronchopulmonary segments
68
Bronchopulmonary segments
These segments are further broken into compartments called
lobules
69
Each lobule is wrapped in
elastic connective tissue
70
§ Each lobule contains
a lymphatic vessel, an arteriole, a venule, and a branch from a terminal bronchiole
71
slide 121 pic
121
72
Lobules continued
| § Terminal bronchioles branch inside these lobules into
multiple respiratory bronchioles
73
begin budding from these respiratory bronchioles
Alveoli
74
This is where gas exchange begins
Alveoli
75
This is why the beginning of the respiratory zone starts
| at the respiratory bronchiole
Alveoli - This is where gas exchange begins
76
slide 123 shows the microscopic airways from top to bottom
look at image and table on top right
77
Alveolar sac (sometimes called an
acinus)
78
§ Two or more alveoli sharing same alveolar duct
| § Looks like a bunch of grapes
Alveoli
79
Cup-shaped out-pouching from alveolar duct
Alveoli
80
~300 million alveoli in human lungs
Alveoli
81
Adjacent alveoli are connected by
“pores”
82
These allow for air movement between the alveoli
“pores”
83
This helps to equalize pressure throughout the alveolar sac
“pores”
84
125 slide
125
85
Walls of alveoli contain two types of epithelial cells
```
Type I (alveolar cells) – more numerous, form an
almost continuous lining of the alveolar wall § main site for gas exchange
```
```
Type II (septal cells) – fewer in number, positioned
sporadically in-between the type I cells
```
86
– more numerous, form an almost continuous lining of the alveolar wall
§ main site for gas exchange
Type I (alveolar cells)
87
main site for gas exchange
Type I (alveolar cells)
88
– fewer in number, positioned sporadically in-between the type I cells
Type II (septal cells)
89
Secretes alveolar fluid (keeps cell surface and air moist)
This fluid contains surfactant (viscous liquid)
```
Type II (septal cells) – fewer in number, positioned
sporadically in-between the type I cells
```
90
This fluid contains surfactant (viscous liquid)
Some from the club cells in terminal bronchioles, and some
from its own supply
alveolar fluid from Type II (septal cells)
91
Not embedded in the walls of the alveoli, but inside
| it are
§ Alveolar macrophages (dust cells) – phagocytes
§ Monocytes (fibroblast-like cells) – produce reticular
and elastic fibers
92
§ Alveolar macrophages AKA
(dust cells) – phagocytes
93
§ Monocytes AKA
(fibroblast-like cells) – produce reticular
| and elastic fibers
94
pic 127
127
95
A complex mixture of phospholipids and lipoproteins
Alveolar Fluid
96
Alveolar Fluid
A complex mixture of
phospholipids and lipoproteins
97
Lowers surface tension of alveolar fluid
surfactant of alveolar fluid
98
Reduces the tendency of alveoli to collapse
| § Helps maintain their patency
surfactant of alveolar fluid
99
Reduces the tendency of alveoli to collapse
| § Helps maintain their patency
surfactant of alveolar fluid
100
We want ___ surface tension in pleural cavity to
| keep parietal and visceral layers together
high
101
§ This helps keep the lungs inflated
| § This is why there is NO surfactant in pleural fluid
high surface tension in pleural cavity
102
We want __ surface tension inside the alveoli to keep
| these layers apart during exhalation
low
103
With increased surface tension, when the alveoli collapse
| (think flat soccer ball), the tension will
keep the alveoli collapsed
104
Inhaled air will have to have
high enough pressure to break the surface tension bond
105
This is why there is surfactant in alveolar fluid
To keep the alveoli from collapsing
We want low surface tension inside the alveoli to keep
these layers apart during exhalation
106
Takes place by diffusion across alveolar and capillary walls
O2 and CO2 Exchange
107
These two layers form the respiratory membrane
alveolar and capillary walls
108
is only 0.5 micrometers thick (1/16th the
| size of a RBC)
Respiratory Membrane
109
Respiratory Membrane
This thin wall allows for
rapid diffusion of gases
110
It is estimated that the lungs contain 300 million
alveoli
The surface area of all of these is approximately
750ft2 (size of a tennis court)
This gives expansive surface area for...
...efficient oxygen/carbon dioxide exchange
111
131 and 132 pretty pics
131 132
112
Blood Supply of the Lungs
| § Receives blood via two separate sets of arteries:
Pulmonary arteries (only arteries in body that carry deoxygenated blood)
§ Pulmonary trunk (coming from right ventricle) gets divided into left and right pulmonary arteries
§ These enter the left and right lungs respectively
Bronchial arteries
§ Branches off of the aorta that deliver oxygenated blood
to the lungs
§ This blood perfuses the muscular walls of bronchi and
bronchioles
113
(only arteries in body that carry deoxygenated blood)
Pulmonary arteries
114
(coming from right ventricle) gets divided into left and right pulmonary arteries
§ These enter the left and right lungs respectively
§ Pulmonary trunk
115
§ Branches off of the aorta that deliver oxygenated blood
| to the lungs
Bronchial arteries
116
§ This blood perfuses the muscular walls of bronchi and
| bronchioles
Bronchial arteries
117
Blood Supply of the Lungs
§ Returns blood to left atrium via
§ Pulmonary veins (4 in total; two each lung)
| § Return of oxygenated blood to the left atrium
118
3 basic steps of respiration
Pulmonary ventilation (breathing)
External Respiration
Internal respiration
119
§ Inhalation and exhalation of air
| § Involves exchange of air between atmosphere and alveoli
Pulmonary ventilation (breathing)
120
§ Exchange of gases between alveoli and blood in
pulmonary capillaries
§ Pulmonary capillary blood gains O2 and loses CO2
External respiration
121
§ Exchange of gases between systemic capillaries and
tissue cells
§ Blood loses O2 and gains CO2
§ The metabolic reaction that consumes O2 and gives off
CO2 within the cells is called cellular respiration
Internal respiration
122
Pulmonary capillary blood gains O2 and loses CO2
External respiration
123
Blood loses O2 and gains CO2
Internal respiration
124
The metabolic reaction that consumes O2 and gives off
| CO2 within the cells is called cellular respiration
Internal respiration
125
Pulmonary Ventilation
§ Air flows between atmosphere and alveoli
§ This occurs because of the alternating pressure difference created by...
...contraction and relaxation of respiratory muscles
126
Pulmonary Ventilation
§ Rate of airflow as well as amount of effort needed
for breathing are influenced by:
§ Alveolar surface tension (surfactant)
§ Compliance of lungs (ex: fibrosis)
§ Airway resistance (ex: asthma)
127
Pressure Changes in Ventilation
§ Air moves into lungs when pressure is greater in the
atmosphere (environment)
§ Think of C-PAP
§ Continuous positive air pressure machine for obstructive
sleep apnea patients
§ It increases the pressure at which air moves into the airways so that it can overcome anatomical abnormalities that may close off the airway otherwise
128
§ Air moves out of the lungs when...
the pressure is less in the atmosphere (environment)
129
142 pic
142
130
`Breathing
Pulmonary ventilation
131
§ External (pulmonary) respiration
Exchange of gases between alveoli (lungs) and blood
| pulmonary capillaries
132
Exchange of gases between systemic capillaries and
| tissue cells
Internal (tissue) respiration
133
Atmospheric pressure
The pressure of the air just outside of the body’s
| airway
134
Intrapleural (intrathoracic) pressure
Fluid pressure between the visceral and parietal
| layers of the pleura
135
Alveolar (intrapulmonic) pressure
Pressure inside the lungs
| ----Specifically the collective pressure within the alveoli
136
Inhalation (Inspiration)
§ Just before the start of each inhalation, pressure in
lungs is
equal to atmospheric pressure (at sea level)
§ 760mmHg (or 1 atmosphere)
137
For airflow to occur, the pressure in the alveoli must
| become
lower than the atmosphere
138
For airflow to occur, the pressure in the alveoli must
become lower than the atmosphere
§ This is accomplished by increasing the size of the
lungs (and the thoracic cavity)
§ By contracting certain muscles, it pulls the pleura
outward, creating a larger cavity, and therefore less
pressure within it
139
Inhalation- Boyles Law
The pressure of a gas in a closed container is
inversely proportional to the volume of the container
140
Inhalation- Boyles Law
If container (volume) becomes bigger – pressure
decreases
141
Inhalation- Boyles Law
If container (volume) becomes smaller – pressure
increases
142
For inhalation to occur:
| § Thoracic cavity size (volume) must
increase
143
Due to cohesion of visceral and parietal pleura, the
| lungs expand as the cavity expands therefore
increasing intra-alveolar volume
This creates a lower alveolar pressure (sub-atmospheric)
144
This allows air to flow in
Thoracic cavity size (volume) must
145
To expand the lungs, the main muscles of
| inhalation must contract
§ Diaphragm
| § External intercostals
146
– most important muscle of inhalation
Diaphragm
147
What determiners transition to bronchioles?
Lack of cartilage
148
Dome shaped skeletal muscle that forms floor of thoracic cavity
Diaphragm
149
Diaphragm innervation?
Innervated by fibers of the phrenic nerves (C3/C4/C5)
150
Contraction of diaphragm causes it to
This occurs during
flatten
inhalation
151
The contraction of diaphragm increases
This causes...
vertical diameter in thoracic cavity
....increased volume, meaning decreased pressure – air flows in
152
150 inhalation vs exhalation picture
150 pic
153
diaphragm contracts
inhalation
diaphragm moves down
154
diaphragm relaxes
exhalation
diaphragm moves up
155
During normal inhalation, the diaphragm descends approximately 1cm
This produces a pressure difference of 1-3mmHg
This causes...
...an inhalation of approximately 500mL of air
156
During strenuous breathing, the diaphragm may descend up to 10cm
This produces a pressure difference of 100mmHg
This causes...
...an inhalation of approximately 2-3L of air
157
Contraction of diaphragm is responsible for
75% of the air that enters the lungs during normal breathing
158
When these contract, they elevate the ribs
External Intercostal Muscles
159
External Intercostal Muscles contraction:
This causes an increase in the ___ and ___ diameters of the chest cavity
anteroposterior and lateral
160
Contraction of these account for the other 25% of air entering the lungs in normal breathing
External Intercostal Muscles
161
slide 153 images of inspiration and expiration.... pay attention to the chest wall expansion and contraction
please my good man
162
During normal inhalation
Pressure in pleural cavity (intrapleural pressure) is always
lower than atmospheric pressure
163
Just before inhalation begins, the pleural cavity is approximately 4mmHg less than atmospheric pressure (756mmHg)
As diaphragm and external intercostals contract, overall size of thoracic cavity
increases (decreasing pressure)
164
as size of thoracic cavity increases during inhalation, this causes intrapleural pressure to
decrease as well to 754mmHg
165
Normally parietal and visceral pleurae adhere tightly because of the __ and ___
subatmospheric pressure AND the surface tension created by their moist surfaces
166
During normal inhalation (continued)
Pleural Pressures
As thoracic cavity expands, the parietal pleura lining the cavity is....
This takes the visceral pleura and therefore ____
pulled outward in all directions
the lungs with it
167
During normal inhalation (continued)
Pleural Pressures
As volume of lungs increase, the alveolar (intrapulmonic) pressure is
This creates the pressure difference between the....
the pressure difference causes what?
reduced from 760mmHg to 758mmHg
.....atmosphere (now higher pressure) and the alveoli (now lower pressure)
AIR FLOWS IN!!
168
Accessory Muscles for inhalation
| (3) and what they elevate?
Sternocleidomastoids- elevate sternum
Scalenes- elevate first two ribs
Pectoralis minors- elevate 3rd-5th ribs
169
Accessory Muscle Use
During deep, forceful inhalations, accessory muscles help to...
Do they help during normal breathing?
... increase thoracic cavity size
These muscles make little to no contribution during normal breathing, but during exercise, or forced ventilation they contract vigorously
170
Inhalation involves muscular contraction to complete it
This makes it an _____ process
ACTIVE
171
Normal exhalation does not include muscular contractions to accomplish
This makes it a _____ process
PASSIVE
172
Does inhalation involve muscular contraction normally?
YES... it's an ACTIVE Process
173
Does Normal exhalation include muscular contractions?
No... it's a PASSIVE Process
174
Exhalation/Expiration
Also occurs from a pressure gradient but in the opposite direction of inhalation
Pressure in lungs is
greater than pressure in atmosphere
175
During normal exhalation, process is passive as no muscular contractions are needed to exhale: This is do to what three characteristics?
The recoil of elastic fibers in the lung tissue
The recoil of smooth muscle of the airways
The inward pull of surface tension in alveoli due to the film of alveolar fluid
176
Exhalation begins when inspiratory muscles start to relax
Diaphragm relaxes causing it to __ ___
External intercostals relax causing ?
All of this decreases the __, __ and ____ diameters decreasing the cavity size and therefore...?
Diaphragm relaxes causing it to move upward
External intercostals relax causing ribs to depress
All of this decreases the vertical, lateral and anteroposterior diameters decreasing the cavity size and therefore
...decreasing the lung volume
177
Exhalation
As this process occurs, the alveolar (intrapulmonic) pressure is...
This increase in pressure causes air to flow how?
...increased to approximately 762mmHg
from high pressure to low pressure…exhalation
178
Forced Exhalation
Exhalation becomes an active process only during
forceful breathing (ex's: Playing a wind instrument, Exercise)
179
Forced Exhalation
During this process, muscles of exhalation contract
Abdominals – contraction moves...
... inferior ribs downward, compressing abdominal viscera
180
Forced Exhalation
– pulls ribs inferiorly when contracting, helps put pressure on abdominal viscera
Internal intercostals
181
Other Factors Affecting Ventilation
We know that pressure differences drive airflow, but three other factors contribute to the rate of airflow and the ease of pulmonary ventilation
Surface tension of alveolar fluid
Compliance of the lungs
Airway resistance
182
Remember…a thin layer of fluid coats the luminal surface of the alveoli (the inside of the bubble)
This fluid exerts a force known as
surface tension
183
Found at all air-water interfaces due to the polar water molecules being strongly attracted to each other rather than to gases
surface tension
184
When liquid surrounds a gas circumferentially (as in an alveolus or a soap bubble) it creates an inwardly directed force
surface tension
185
slide 165
165
186
Surface Tension of Alveolar Fluid
Surface tension (in the lungs)
Causes alveoli to assume...
...their smallest possible diameter (around the gas inside)
187
Surface tension must be overcome to...
expand the lungs during each inhalation
188
Accounts for 2/3rds of elastic recoil during exhalation
Surface tension
189
Surfactant role
Reduces the amount of what affecting which part of the lungs?
constant inward pressure that is pulling the walls of the alveoli together
190
Helps alveoli avoid collapse
Also allows alveoli to open with less air pressure (becomes more compliant)
Surfactant
look at slide 167 for a great visual
