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Chapter 22— The
Respiratory System
22-1
Ch. 22 (Respiratory Sys.)
Study Guide
1. Critically read Chapter 22 pp. 864-886 right
before 22.3 “Gas Exchange and Transport”
section
2. Comprehend Terminology (those in bold)
3. Study-- Figure questions, Think About It
questions, and Before You Go On (sectionending) questions
4. Do end-of-the-chapter questions:
– Testing Your Recall— 1-5, 7, 10, 11-18
– True or False– 1, 2, 4-6, 8
– Testing Your Comprehension– 1, 4, 5
2
Breathe/Breath (1 or 2)
Fear less, hope more;
Whine less, breathe more;
Talk less, say more;
Hate less, love more;
And all good things are yours.
--Swedish proverb
22-3
Breathe/Breath (2 of 2)
Every day brings a chance
for you to draw in a breath,
kick off your shoes,
and dance.
--Oprah Winfrey
22-4
§ I. Anatomical Consideration
Self-Check Question: As we breathe in,
what respiratory organs, in order, does
air pass through?
Answer: Nose (mouth) . . .
Fig. 22.1
22-5
1
§ Organs of
Respiratory
System
2
3
4
5
6
22-6
General Aspects
1. Airflow in lungs
– bronchi  bronchioles  alveoli
2. Conducting & Rspiratory (C/R) divisions-– (C) passages ONLY for airflow, nostrils to
bronchioles
– (R) distal gas-exchange regions and ________
3. Upper/lower (U/L) respiratory tracts
– (U) organs in head and neck, nose through
larynx
– (L) organs of trachea through lungs
22-7
§ 1. Nose
• Bony and cartilaginous; supported by:
– superior half: nasal bones medially and
maxillae laterally
– inferior half: lateral and alar cartilages
– ala nasi: flared portion shaped by alar
cartilages and dense CT; forms lateral wall of
each nostril
– Fig. 22.2 a+b
22-8
Conn. tissues shape the nose
(Ala nasi)
22-9
External Anatomy of Nasal Region
22-10
Nasal Cavity (1)
1. Extends from nostrils to posterior nares
2. Vestibule: dilated chamber inside ala nasi
(just inside the nostril)
– stratified squamous epithelium and vibrissae
(guard hairs)
3. Nasal septum divides cavity into right and
left chambers called nasal fossae
– Makes up of = Perpendicular plate of ethmoid
bone + . . .
22-11
Nasal Cavity (2) - Conchae and Meatuses
1. Superior, middle and inferior nasal
conchae
– 3 folds of tissue on lateral wall of nasal fossa
– mucous membranes lines the cavity
2. Meatuses:
– narrow air passages beneath each conchae
– narrowness and turbulence ensures most air
contact the mucous membrane.
Fig. 22.3
22-12



22-13
Skull--
2
3
1
Figure 8.4b
4
5
6
8
10
11
7
9







Palatine bones

Functions of the nose
• Nose (mouth)—air enters the body
through here
Functions—
• Warm and moisten air
• Produce nasal mucus– how much
each day? By epi. cells
• Cilia– push particles toward the
throat
22-16
§ 2. Pharynx (throat)
Functions—
• Common entryway of . . .
• Food and air diverge into two
separate branches
• Air  which organ next?
• Food  which organ next?
Which passage way (air or food) is at
the anterior?
Figure 22.3 b+c
22-17
22-17
Lower respiratory tract
22-18
Three Regions of Pharynx
Hyoid
bone
Cricoid
cartilage
22-19
§ 2. Pharynx (continued)
• Nasopharynx (pseudostratified epithelium)
– posterior to choanae, dorsal to soft palate
– receives auditory tubes; houses _____ tonsil
– 90 downward turn; traps large particles (>10m)
• Oropharynx (stratified squamous epithelium)
– space between soft palate and root of tongue,
inferiorly as far as hyoid bone, contains
palatine and lingual tonsils
• Laryngopharynx (stratified squamous epi.)
– hyoid bone to level of cricoid cartilage
22-20
§ 3. Larynx (Voice box)
– Anatomy—anterior protrusion called ?
– Functions—
• Air passageway with cilia
• Epiglottis– superior opening of larynx
• Voice production by ____________
• Laryngitis—Inflammation of the vocal
cords; symptoms? Three major causes?
22-21
Larynx
• Glottis – vocal cords and opening between
them
• Epiglottis
– flap of tissue that guards glottis, directs food
and drink to esophagus
• Infant larynx; epiglottis touches soft palate
– higher in throat, forms a continuous airway
from nasal cavity to the larynx that allows
breathing while swallowing
– by age 2, more muscular tongue, forces larynx
down to lower position
22-22
Nine Cartilages of Larynx
The superior three (large):
1.Epiglottic cartilage (1)- most superior
2.Thyroid cartilage (1)– largest; laryngeal
prominence is the Adam’s apple
3.Cricoid cartilage (1)- connects larynx to
trachea
• Fig. 22.4
22-23
Views of Larynx
1
2
4
5-6
3
22-24
Nine Cartilages of Larynx
The other 3 small pairs of cartilages:
4.Arytenoid cartilages (2) - posterior to thyroid
cartilage
5.Corniculate cartilages (2) - attached to
arytenoid cartilages like a pair of little horns
The above two pairs of cartilages function in speech
6.Cuneiform cartilages (2) - support soft tissue
between arytenoids and epiglottis
22-25
Walls of Larynx
• Interior wall has 2 muscular folds on each
side, from thyroid to arytenoid cartilages
– Vestibular folds (superior pair) and vocal
cords/folds (inferior) (produce sound)
• Intrinsic muscles (deep)- rotate corniculate
and arytenoid cartilages (Fig. 22.6)
– adducts (tightens: high pitch sound) or abducts (loosens: low
pitch sound) vocal cords
• Extrinsic muscles (superficial)- connect
larynx to hyoid bone, elevate larynx during
swallowing
22-26
High pitch
low pitch
22-27
§ 4.Trachea (windpipe)
Anatomy/Histology: Beginning of lower
respiratory tract (Fig. 22.7 a-c +x)
1. Rigid tube 5 in. long and 1 in. diameter,
anterior/posterior (?) to the esophagus
2. Supported by 16 to 20 C-shaped rings;
openings facing anterior/posterior (?)
•
The lowermost cartilage called ________
3. A smooth m. (trachealis) spans opening in
rings, adjusts airflow; facing (ant./post.?)
4. (Histology) Larynx and trachea lined with
ciliated pseudostratified columnar epi. which
functions as mucociliary escalator
22-28
Larynx
Trachea
Carina
See
next
three
slides
22-29
22-30
Ciliated Pseudostratified Epi.
22-31
Mucosa
22-32
ID structures: Practice at home
A
B
C
D
E
22-33
§ 4. Trachea (continued)
Functions:
– Air passageway
– Warm and moisten air
– Remove particles & debris
Clinical applications:
– Trachea obstruction and Heimlich
Maneuver
– Tracheostomy (Insight 22.1) when the
obstruction is superior to the level of
the larynx; pitfall?
22-34
§ 5. Bronchi (supported by cartilages)
A. Primary bronchi (2); with C-shaped rings
– from trachea; after 2-3 cm enter hilum of lungs
– right bronchus slightly wider and more vertical
B. Secondary (lobar) bronchi (2 L. lung+ 3 R.
lung); one secondary bronchus for each
lobe of lung; cartilage plates
C. Tertiary (segmental) bronchi (8 L. lung +
10 R. lung); cartilage plates
– bronchopulmonary segment: portion of lung
supplied by each tertiary bronchus
22-35
Fig. 22.7
All bronchi
are
supported
by
cartilages
22-36
§ 6. Bronchioles
Bronchioles (lack cartilage; 1 mm or less in diameter;
ciliated simple columnar to ciliated simple cuboidal epi.)
A. Each divides into 50 - 80 terminal bronchioles
• Mostly nonciliated simple cuboidal; end of
conducting division
B. Each terminal bronchiole branches into
respiratory bronchioles (respiratory div.
now); smallest ones are nonciliated epi.
C. Each divides into 2-10 alveolar ducts
(nonciliated simple squamous epi.); end in
alveolar sacs
22-37
• Fig. 22.11
§ Bronchial tree
Def. --Highly branched system of air
tubes from the primary bronchi to
about 65,000 terminal bronchioles
Resemble inverted trees
Fig. 22.0 + X
22-38
Right lung; 10
segments
CO 22
Each
bronchopulmonary
segment by
a different
color of
resin
Left lung; 8
segments
22-39
Right lung;
10 bronchopulmonary
segments
Left lung; 8
bronchopulmonary
segments
22-40
§ 7. Lungs (Fig. 22.9 a + b)
– Concave base and blunt apex
– Costal surface-– Concave mediastinal surface—
– The hilum (hilus)– slits/depression where
bronchi, blood vessels, nerves
entering/leaving
– The right lung– shorter; the left lung–
narrower, with cardiac impression
– L– 2 lobes separated by a fissure
– R– 3 lobes separated by two fissures
22-41
22-42
22-43
§ 8. Alveoli meaning hollow
1. Def.– tiny air sacs where . . .
2. Anatomy/physiology—
•
Each alveolus– single layer of epithelium
surrounded by ____________________
•
Numerous alveoli (150 million) in each
lung
Figure 22.12
22-44
Alveolar
Blood
Supply
22-45
§ Alveoli—Pore of Kohn
Pore of Kohn
•
Location?
•
Function?
•
Analogy—
Fig. x
22-46
1.Terminal
bronchiole
A. Branch of
pulmonary
artery
Smooth
muscle
C. Branch of
pulmonary
vein
2. Respiratory
Bronchiole
(beginning of
respiratory
division)
3. Alveolus
Pores of Kohn
B. Pulmonary
capillaries
Alveolar sac
22-47
§ Alveoli—Three types of cells
A. Squamous (Type I) alveolar cells—
•
•
•
Location?
Function--Gas exchange through these
sites; What type of epi.?
Respiratory membrane– 0.5 micrometer;
the barrier between alveolar air and _____
B. Great (Type II) alveolar cells—
•
•
Location? Embed within alveolar walls
Functions— secretes surfactant & repairs
Figure 22.12
22-48
Fluid lining
With surfactant
B. Great
alveolar cell
Pulmonary
capillary
A. Squamous
alveolar cell
C. Alveolar
macrophage
Alveolus
O2
Respiratory mem.
RBC
22-49
§ Alveoli—Three types of cells
C. Alveolar macrophages (dust cells)—
• Most numerous of all cells in the
lung
• Large tissue-bound phagocytes
• Location– within the alveolar lumen
• Function-- Phagocytosis
22-50
Practice
at home
D
A
B.
Identify A,
B, C, and D.
C
Fig. 22.11
What is
respiratory
membrane?
b and c
Respiratory mem.
22-51
Questions (muddiest
points)?
22-52
§ II. Pulmonary Ventilation
1. Respiratory cycle– One complete cycle of
inspiration and expiration
– Breathing (pulmonary ventilation) – repeated
cycles above
2. Quiet respiration vs. forced respiration –
3. Basic requirement of respiration:
– Flow of air in and out of lung requires a
______________ between air pressure within
lungs and outside body; why? (next slide) 22-53
§ Breathing- mechanical steps
1. Why flow of air into and out of the lungs
during the breathing?
2. A rule of thumb—
•
•
PV = K (Boyle’s law) with Temp. is constant
For example, during inspiration: lung volume
increases lung pressure decreases 
therefore, air flow (from where to where?
_____________________)
Figure x (Boyle’s Law explained)
22-54
Each container Figure
with the same
13.10
number of gas molecules
Piston
Page 467
Piston
Piston
Pressure
gauge
A. Volume = 1/2
Pressure = 2
B. Volume = 1
Pressure = 1
C. Volume = 2
Pressure = 1/2
PV = K
22-55
§ Breathing- mechanical steps
3. Mechanism of Inspiration (resting)—
A. Diaphragm contracts and move ______?
B. External intercostals muscles contract 
the ribs move __________?
C.  Chest volume _________?
D.  Air pressure is _________?
(Boyle’s law)
E.  Air flows inward
4. Deeper Inspiration—
A. Neck muscles (among others) are also
involved
5 Figures
22-56
Diaphragm
A 2-dimentional figure
22-57
2. Contraction
of external
intercostal
muscles
increases
side-to-side
dimension
(x)
increases
front-toback
Dimension
(y)
Quiet Inspiration
1. Contraction
of diaphragm
increases
vertical
dimension of
(z)
A 3-dimentional figure
22-58
Equilibrated;
no net
movement of
air
760 mmHg
Before inspiration
Preinspiratory
size of thorax
760 mmHg
Preinspiratory
size of lungs
22-59
760 mm Hg
During inspiration
Size of thorax  on
contraction of
inspiratory muscles
757-759
mm Hg
(from 760)
Size of lungs  as
they
are stretched to fill
the expanded
thorax; pressure 
Demonstration
—lung model
22-60
Muscles of
deeper
inspiration
1. Sternocleidomastoid
2. Scalenus
Muscles
of active/forced
expiration
Internal
intercostal
muscles
1. External
intercostal
muscles
2. Diaphragm
Major
muscles of
inspiration
Abdominal
muscles
22-61
§ Breathing- mechanical steps (students
practice on this; KEY on next slide)
5. Mechanism of Expiration—
A. Diaphragm ________ and becomes ______
B. External intercostal muscles ____  the ribs
move ______
C.  Chest volume _________?
D.  Air pressure is _________?
(Boyle law)
E.  Air flows outward
6. Forced expiration: abdominal and
internal intercostal muscles are involved
Figures 22.13
22-62
Relaxation
of external
intercostal
muscles
Contraction
of internal
intercostal
muscles
Contraction of internal intercostal
muscles flattens ribs and
sternum, further reducing
side-to-side and front-to-back
dimensions of thoracic cavity
A review slide
on expiration
Contraction
of abdominal muscles
Relaxation of
diaphragm
Passive expiration
Return of diaphragm, ribs, and sternum
to resting position on relaxation of
inspiratory muscles restores thoracic
cavity to preinspiratory size
Position of relaxed
abdominal muscles
Contractions of abdominal
muscles cause diaphragm to
be pushed upward, further
reducing vertical dimension
of thoracic cavity
Active expiration
22-63
760 mm Hg
During expiration
Size of thorax on
relaxation of
inspiratory
muscles
761 mm Hg
(from 760)
Size of lungs as
they recoil
22-64
§ Summary of respiratory muscles (This
slide for review with Fig. x next)
1. Diaphragm (dome shaped)
– contraction flattens diaphragm
2. External intercostals
– increases X&Y diameter; stiffen thoracic cage
3. Scalenes - hold first 2 pair of ribs stationary
4. Pectoralis minor, sternocleidomastoid and
erector spinae muscles
– used in forced inspiration
5. Abdominals, internal intercostals, and
latissimus dorsi
– forced expiration (to sing, cough, sneeze)
– Valsalva maneuver– raise abdominal pressure . . .
22-65
Forced Inspiration
Forced
Expiration
Quiet
Inspiration
22-66
§ III. Neural Control of Breathing
22-67
§ Neural Control of Breathing (1)
1. Breathing depends on repetitive stimuli from the
brain—controlled at two levels (A & B below):
A. Neurons in medulla oblongata and pons
control unconscious breathing
• Ondine’s curse – brainstem damage
• Causes– Poliomyelitis etc.
• Symptoms– disabled automatic respiratory
functions
• Cure-B. Voluntary control provided by motor
cortex is cerebral and consciously controlled
22-68
§ Neural Control of Breathing (2)
2. Unconscious breathing:
A. Inspiratory neurons: fire during
inspiration
B. Expiratory neurons: fire during forced
expiration
C. Fibers of phrenic nerve go to
diaphragm; intercostal nerves to
intercostal muscles
22-69
§ Three Respiratory Control Centers
in the brainstem (Fig. 14.4)
1. Ventral respiratory group (VRG) in medulla
• Primary generator of respiratory rhythm
• Having both inspiratory and expiratory neurons,
taking turns to fire  spinal integrating centers
2. Dorsal respiratory group (DRG) in medulla
• An integrating center– inputs from . . . (Fig. 22.4)
• Output to the VRG modifying respiratory rhythm
3. Pontine respiratory group (PRG) in pons
• Modifies the rhythm of the VRG
• Making each breath shorter/shallower OR longer/
deeper– during sleep, exercise, etc.
22-70
Anterior
1. from higher
brain centers
Pons
3. Central Chemoreceptors
4. CN IX and X
2. PRG
DRG
VRG
Medulla
Spinal integrating
centers
22-72
§ Input to the respiratory centers
1. Central chemoreceptors (in medulla)
• primarily monitor pH (and CO2) of CSF
2. Peripheral chemoreceptors (Fig. 22.15)
– Monitor pH, O2 and CO2 and fibers synapse
to the DRG
3. Stretch receptors (bronchi and bronchioles)
– Excessive inflation triggers inflation reflex
and stops inspiration
4. Irritant receptors (epithelial cells of the airway)
– Respond to particles and trigger coughing
etc.
22-73
22-74
§ Voluntary Control of breathing
• Neural pathways
– motor cortex of frontal lobe of cerebrum sends
impulses down corticospinal tracts to
respiratory neurons in spinal cord, bypassing
brainstem
• Limitations on voluntary control
– blood CO2 and O2 limits cause automatic
respiration overrides one’s will
• Voluntary control is important in singing,
speaking, breath-holding
22-75
Check Point Questions
Q--Where exactly are the medulla
oblongata and the pons located,
respectively?
Answer: medulla oblongata is the most caudal
part of the brainstem (stalklike lower
portion of the brain), immediately superior
to the spinal cord
• The pons is a part of the brainstem located
immediately superior to the medulla
oblongata and ventral to the cerebellum
22-76
Q-- Is it possible that
temperamental children may
hold their breath until they die?
§ Next section--IV. Pressure,
Resistance, and Airflow
22-77
§ Pressure and Airflow (1)
Introduction– (Mostly we have talked about)
1.Atmospheric (barometric) pressure-– 1 atmosphere (atm) = 760 mmHg
2.Intrapulmonary pressure and lung volume
– pressure is inversely proportional to volume
• for a given amount of gas, as volume , pressure 
and as volume , pressure 
3.Pressure gradients matters to airflow-– difference between atmospheric and
intrapulmonary pressure
– Airflow (F) = ΔP (pressure gradient)
22-78
§ Pressure and Airflow (2)
During inspiration; how lungs are expanded?
1. Ribs swing upward and outward  lungs
expand with thoracic cage
•  intrapulmonary pressure (-3 mm Hg; 3 mm
Hg below atmospheric pressure)
• 500 ml of air flows into the lungs (tidal volume)
2. Another force expands the lungs– warming of
the inhaled air. Inhaled air expands, it helps to
inflate the lungs. (Charles’s law)
• Charles’s law– volume of given quantity of gas
is directly proportional to its absolute
temperature
22-79
§ Pressure and Airflow (3)
Recoiling mechanisms during expiration:
1. During quiet breathing, expiration achieved by
elasticity of lungs and thoracic cage etc.
2. As volume of thoracic cavity , intrapulmonary
pressure  (+3 mm Hg) and air is expelled
3. Pulmonary elasticity related disorders:
– Atelectasis– The collapse of a lung
– Causes– A) Pneumothorax (air in the pleural
cavity; see next slide), B) airway obstruction
(that part of lung collapses b/c it cannot be
reventilated, for example inadequate
surfactant, aspirated object etc.
22-80
§ Pneumothorax
•
•
•
Def.—abnormal condition of air
entering the pleural sac
Causes— (see fig. x)
Consequences— transmural pressure
gradient no longer exists and . . .
Figure x
22-81
760
Atelectasis
(pneumothorax)
A
760
760
B
760
C
760
760; intrapulmonary
pressure
756;
intrapleural
pressure
Collapsed lung
A– Parietal pleura; B—pleural cavity (pleural
fluid); C– Visceral pleura
22-82
§ Pulmonary surfactant (1)
1. A potential problem of breathing
•
•
In alveoli—tiny sacs . . .; why?
b/c surface tension of water— Fig. z
2. Solution-- pulmonary surfactant
•
•
•
What is it? Phospholipoproteins
Where does it from? By what cell type?
Functions?
22-83
Demonstration
H2O molecules
An alveolus
22-84
§ Pulmonary surfactant (2)
3. (Newborn/Infant) respiratory distress
syndrome (IRDS)—
A. What is lacking in premature infants?
B. What are the problems?
•
•
•
When surfactant is produced?
Alveoli collapsed completely —
Newborn’s muscles--
C. Cure-85
Check Point Questions
• What types of cells make up the
wall of an alveolus? Function?
• What type of cell in the lungs
secrete pulmonary surfactant?
Function?
22-86
§ V. Alveolar Ventilation
22-87
§ Alveolar Ventilation (1)
Does all inhaled air enter the alveoli?
1. Dead air (150 ml per breath)
– fills conducting division of airway, cannot
exchange gases with the blood
2. Where is the dead air? In anatomic
dead space:
– It exists in conducting division of airway
– Normally about _______mL
3. Physiological (total) dead space
– sum of anatomic dead space and any
pathological alveolar dead space
22-88
§ Alveolar ventilation (2)
1. Alveolar ventilation rate (AVR): body’s
ability to get oxygen to the tissues per
minute
– alveolar ventilation rate (AVR) = (Tidal
volume - dead space volume) x
respiratory rate
– AVR = (500-150mL) x 12 breaths/min =
4,200 mL/min
89
§ Measurements of Ventilation (1)
1. Spirometer – measures ventilation;
specifically respiratory volumes and
capacities
Fig. x
22-90
Floating drum
Air
Recording
paper
advancing
with time
Spirogram
Water
Expired
air
Inspired air
22-91
§ Measurements of Ventilation (2)
2. Respiratory volumes:
A. Tidal volume (TV) - The air entering or leaving
the lungs in a single breath.
B. Inspiratory reserve volume (IRV) - The extra
air that can be maximally inspired over the
typical resting TV.
C. Expiratory reserve volume (ERV) - The
maximal volume of air that can be actively
expired beyond a tidal volume.
D. Residual volume (RV) - air remaining in lungs
after maximum expiration
92
Fig. 22.17
a capacity is the sum of more than two volumes
2


1

3
4

22-93
§ Measurements of Ventilation (3)
3. Respiratory capacities:
A. Inspiratory capacity (IC) - The maximum
volume of air that can be inspired at the end of a
normal quiet expiration. = TV + IRV
B. Functional residual capacity (FRC) – Amount
of air remaining in the lungs after a normal tidal
expiration; = RV + ERV
C. Vital capacity (VC) - The maximum volume of air
that can be expired following a maximal
inspiration. = TV + IRV + ERV
D. Total lung capacity (TLC) - maximum amount of
94
air lungs can hold; = VC + RV
ID the following respiratory
volumes/capacities
D
A
F
G
H
B
C
E
Work on this figure at home.
22-95
Check Point Question
• If you breathe in as deeply as
possible and then exhale as much
air as you can, which lung volume
or capacity have you
demonstrated?
22-96
§ Lung disorders and spirometry
1. Restrictive disorders– Those having
reduce pulmonary compliance, limiting the
amount to which the lungs can be inflated
• Disorders- black lung disease, tuberculosis
• Spirometry- reduced IC, VC, TLC
2. Obstructive disorders (COPD; Chronic
Obstructive Pulmonary Disease) – those that
interfere with airflow by narrowing or blocking
the airway
• Disorders– asthma, emphysema etc.
• Detection: Forced expiratory volume
(FEV)-- % of vital capacity exhaled/time;
healthy adult - ___________% of VC in 1
97
sec (Fig. Y)
FEV1.0
1 sec interval
22-98