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Chapter 13 – Part 1
The Respiratory System
Organs of the Respiratory system
 Nose
 Pharynx
 Larynx
 Trachea
 Bronchi
 Lungs –
alveoli
Function of the Respiratory System
1. Oversees gas exchanges between the
blood and external environment
2. Exchange of gasses takes place within
the lungs in the alveoli
3. Passageways to the lungs purify,
warm, and humidify the incoming air
The Nose
 The only externally
visible part of the
respiratory system
 Air enters the nose through
the external nares (nostrils)
 The interior of the nose consists of a
nasal cavity divided by a nasal
septum
Figure 13.2
Anatomy of the Nasal Cavity
 Olfactory receptors for the sense of
smell are located in the mucosa on the
slitlike superior part of the nasal cavity
 The rest of the cavity is lined with
respiratory mucosa, which function to:
1. Warm the air
2. Moistens the air
3. Traps incoming foreign particles (cleanse)
Anatomy of the Nasal Cavity
 The ciliated cells of the nasal
mucosa create a gentle current
that moves contaminated mucous
posteriorly towards the throat (pharynx)
 It is then swallowed and digested by stomach
juices.
 When it is extremely cold, these cilia become
sluggish, allowing mucus to accumulate in
the nasal cavity and to dribble outward
through the nostrils.
 This is why you have a “runny” nose on a cold
day.
Nosebleeds
 The respiratory mucosa
rests on a rich network of
thin-walled veins (warms
the air as it flows by).
 Because of the
superficial location of
these blood vessels,
nosebleeds are
common and often
profuse.
Anatomy of the Nasal Cavity
 The lateral walls of the nasal
cavity have three projections
or lobes called conchae,
which function to:
1. Increases surface area
2. Increases air turbulence within the nasal
cavity
 Helps to deflect inhaled particles onto the
mucus-coated surfaces, where they are
trapped and prevented from entering the
lungs.
Anatomy of the Nasal Cavity
 The nasal cavity is separated from the
oral cavity by the palate
 Anterior hard palate (bone)
 Posterior soft palate (muscle)
Cleft Palate
 Cleft Palate – The bones forming the
palate fail to fuse medially
 Genetic defect
 Results in breathing difficulties and
problems with oral cavity functions
(chewing and speaking)
Paranasal Sinuses
 The nasal cavity is surrounded by a ring
of paranasal sinuses.
 Are located in the:
1. Frontal bone
2. Sphenoid bone
3. Ethmoid bone
4. Maxillary bone
Paranasal Sinuses
 Function of the sinuses
1. Lighten the skull
2. Act as resonance chambers for speech
3. Produce mucus that drains into the nasal
cavity
•
The suctioning effect created by nose
blowing helps to drain the sinuses.
•
The nasolacrimal ducts, which drain
tears from the eyes, also empty into
the nasal cavities
Sinusitis
 Sinusitis – Sinus inflammation
 Difficult to treat
 Can cause marked changes in voice
quality
 When the passageways connecting the
sinuses to the nasal cavity are blocked
with mucus or infectious matter, the air in
the sinus cavities is absorbed
 The result is a partial vacuum and a sinus
headache
Pharynx (Throat)
 Pharynx - Muscular
passage from nasal
cavity to larynx
 About 5 inches long
 Commonly called the throat
 Serves as a common passageway for
food and air
 Is continuous with the nasal cavity
anteriorly via the internal nares
Pharynx (Throat)
 Three regions of the
pharynx:
 Nasopharynx – Superior
region behind nasal cavity
 Oropharynx – Middle region behind mouth
 Laryngopharynx – Inferior region attached
to larynx
 The oropharynx and laryngopharynx are
common passageways for air and food
 Air then passes through the larynx, while food
is directed into the esophagus posteriorly
Structures of the Pharynx
 The auditory tubes,
which drain the middle
ear, open into the
nasopharynx
 Since the mucosae of
these two regions are
continous, ear infections
may follow a sore throat
or other types of
pharyngeal infections
Structures of the Pharynx
 Tonsils (clusters of lymphatic
tissue) are also found in the
pharynx
 Their job is to trap and remove any bacteria
or other foreign pathogens entering the
throat
 Pharyngeal Tonsil – Located high in the
nasopharynx
 Palatine Tonsils – Located in the oropharynx at
the end of the soft palate
 Lingual Tonsils – Located at the base of the
tongue
Tonsillitis
 Tonsillitis – Inflammation and swelling of
the pharyngeal tonsil
 Can occur during a bacterial infection
 It obstructs the nasopharnyx and forces the
person to breathe through the mouth
 In mouth breathing, air is not properly moistened,
warmed, or filtered before entering the lungs
 Years ago, the belief was that the tonsils were
more trouble than they were worth and they
were routinely removed.
 Now, this is no longer necessary because of the
large use of antibiotics
Larynx (Voice Box)
 Functions of the Larynx:
1. Routes air and food
into proper channels
2. Plays a role in speech
(voice production)
3. Acts as an airway
 Made of eight rigid hyaline cartilages
and a spoon-shaped flap of elastic
cartilage (epiglottis)
Structures of the Larynx
 Thyroid Cartilage
 Largest hyaline
cartilage
 Shield-shaped
 Protrudes
anteriorly
 Commonly called
the Adam’s apple
Structures of the Larynx
 Epiglottis
 Protects the superior
opening of the larynx
 Routes food to the esophagus
and air toward the trachea
 The epiglottis moves positions when swallowing
 When we are not swallowing: The epiglottis does
not restrict the passage of air into the lower
respiratory passages
 When we are swallowing: The larynx is pulled
upward and the epiglottis tips, forming a lid over
the opening of the larynx; this routes food into the
esophagus
Structures of the Larynx
 Palpate your larynx by placing your
hand midway on the anterior surface of
your neck. Swallow. Can you feel the
larynx rising as you swallow?
Cough Reflex
 If anything other than air
enters the larynx, a cough
reflex is triggered to expel
the substance and to prevent it from
continuing into the lungs.
 Because this protective reflex does not
work when we are unconscious, it is never
a good idea to try to give fluids to an
unconscious person when attempting to
revive him or her.
Structures of the Larynx
 Vocal Cords (vocal folds)
 Pair of folds
 Vibrate with expelled air to
create sound
 Allows us to speak
 Glottis – The slitlike
passageway between the
vocal cords