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Chapter 23 – Anatomy of
the Respiratory System
Dr. Kim Wilson
Introduction to the Respiratory System
• 1. Providing an extensive surface area
for gas exchange between air and
circulating blood.
• 2. Moving air to and from the exchange
surfaces of the lungs.
• 3. Protecting respiratory surfaces from
the outside environment.
• 4. Producing sounds.
• 5. Participating in the olfactory sense.
Filters, warms, and humidifies the air
we breathe
The respiratory tract consists of a
conducting portion (from the nasal cavity to
the terminal bronchioles) and a respiratory
portion (the respiratory bronchioles and
Alveoli are the air-filled pockets within the
lungs where all gas exchange takes place.
Introduction to the Respiratory System
Divided into two divisions for
purpose of study
Upper respiratory tract
• Composition: nose,
nasopharynx, oropharynx,
laryngopharynx, & larynx
Lower respiratory tract
• Composition: trachea, all
segments of the bronchial
tree, & lungs
Accessory structures:
• Oral cavity
• Rib cage
• Diaphram
Upper Respiratory Tract Organs - Nose
• STRUCTURE (2 portions)
• Internal portion (nasal cavity)
• Lies over the roof of the mouth,
separated by the palatine bones
• If bones fail to unit  cleft
palate  difficulty swallowing
• Cribriform plate: separates the
roof of the nose from the cranial
• Septum: separates the nasal
cavity into right and left cavities
• Consists of four structures
• Ethmoid bone, the
vomer bone, the
vomeronasal cartilages,
and the septal nasal
Upper Respiratory Tract Organs - Nose
• Structure cont.
• External portion (visible
• Consists of a bony and
cartilaginous frame
covered by skin containing
sebaceous glands
• The two nasal bones
meet and are surrounded
by the frontal bone to form
the root
• The nose is surrounded by
the maxilla
Upper Respiratory Tract Organs - Nose
• Superior
• Middle
• Inferior
• The meatuses are
passageways that
produce air
turbulence, giving
incoming air time to
warm and humidify,
and particles to be
Upper Respiratory Tract Organs - Nose
• Anterior nares (nostrils):
external openings to the
nasal cavities; open into the
• Posterior nares: internal
openings between nasal
cavities and nasopharynx
• Sequence of air flow through
the nose into the pharynx:
anterior nares  vestibule 
three meatuses simultaneously
 posterior nares
Upper Respiratory Tract Organs – Nose
Nasal mucosa
• A mucous membrane that air passes
over; it contains a rich blood supply
(Figure 23-4)
Olfactory epithelium: special sensory
membrane containing many olfactory nerve
cells and a rich lymphatic plexus
• Tissue Type: Pseudostratified ciliated
columnar epithelium
• Mucous membrane with goblet cells
• Contains cilia
FUNCTION of nasal mucosa
• Prepares inhaled air for arrival at the
lower respiratory organs (warming and
• Breathing through your mouth
bypasses this important step.
Upper Respiratory Tract Organs –
• Paranasal sinuses
• Four pairs of air-containing
spaces that open or drain into
the nasal cavity; each is lined
with respiratory mucosa (Figure
• FUNCTIONS of the nose
• Provides a passageway for
air traveling to and from the
• Filters the air, aids speech,
and makes possible the
sense of smell
Upper Respiratory Tract Organs –
Pharynx (throat)
• Pathway for the respiratory and digestive tracts
• STRUCTURE: a tubelike structure extending from the base of the skull to
the esophagus
• 3 parts
• Nasopharynx - Extends from posterior nares to soft palate
• Oropharynx - Extends from soft palate to hyoid bone
• Contains: the palatine tonsils (most commonly removed) and the
lingual tonsils (rarely removed)
• Laryngopharynx - Extends from hyoid bone to esophagus
• Pharyngeal tonsils: located in the nasopharynx, called adenoids when they
become enlarged
Upper Respiratory Tract Organs –
• Larynx (voice box)
• Air from the pharynx enters the larynx, a
cartilaginous structure that surrounds
the glottis.
• LOCATION: positioned between the root
of the tongue and the upper end of the
• STRUCTURE: consists of cartilages
attached to each other by muscle; lined
by a ciliated mucous membrane, which
forms two pairs of folds
• Vestibular folds (false vocal
• Vocal folds
Upper Respiratory Tract Organs – Larynx
CARTILAGES (framework) of the larynx:
Formed by nine cartilages
Three large, unpaired cartilages form the
• 1. The thyroid cartilage (Adam’s
• hyaline cartilage
• forms anterior and lateral walls
of larynx
• ligaments attach to hyoid bone,
epiglottis, laryngeal cartilages
• 2. The cricoid cartilage:
• hyaline cartilage
• form posterior portion of larynx
• ligaments attach to first tracheal
• articulates with arytenoid
• 3. The epiglottis:
• elastic cartilage
• ligaments attach to thyroid
cartilage and hyoid bone
Upper Respiratory Tract Organs – Larynx
The thyroid and cricoid cartilages surround and protect the glottis and the
entrance to the trachea. During swallowing, the larynx is elevated and the
epiglottis folds back over the glottis, preventing entry of food and liquids into
the respiratory tract.
The larynx also contains 3 pairs of smaller hyaline cartilages:
1. the arytenoid cartilages
2. the corniculate cartilages
3. the cuneiform cartilages
Upper Respiratory Tract Organs – Glottis
FUNCTION – sound production (air
passing through the glottis vibrates the
vocal folds and produces sound waves)
• The corniculate and arytenoid
cartilages function in the opening and
closing of the glottis and the
production of sound.
LOCATION – space between the vocal
Upper Respiratory Tract Organs –
• Intrinsic muscles both insert and originate within the larynx
• Extrinsic muscles insert in the larynx but originate on some other
• FUNCTION: forms part of the airway to the lungs and produces the
Upper Respiratory Tract Organs –
Trachea (Windpipe)
LOCATION - Extends from the larynx to the primary bronchi
• Extends from the cricoid cartilage into the mediastinum where it branches into the
right and left pulmonary bronchi.
Furnishes part of the open airway to the lungs; obstruction causes death
Mucous coat = beneath the mucosa, the trachea has a submucosa that contains the
mucous glands.
The trachea has 15-20 tracheal cartilages that strengthen and protect the airway.
The tracheal cartilages are discontinuous on the posterior side, where the trachea
contacts the esophagus. An elastic ligament and the trachealis muscle connect the
ends of each tracheal cartilage.
Upper Respiratory Tract Organs – Bronchi
• Distribute air to the lung’s interior
• Lower end of the trachea divides into two
primary bronchi (right and left)
• Separated by an internal ridge called the
• The primary bronchi enter the lung and divide
into secondary bronchi, which branch into
bronchioles and eventually divide into
alveolar ducts and alveoli
• The right primary bronchus is larger in
diameter than the left, and descends at a
steeper angle.
• Each primary bronchus travels to a groove
(the hilus) along the medial surface of its
lung, where pulmonary nerves, blood vessels
and lymphatics enter, anchored in a
meshwork of connective tissue. This
complex, called the root of the lung, is
anchored to the mediastinum.
Upper Respiratory Tract
Organs – Alveoli
FUNCTION - Primary gas
exchange structures
Microscopic grapelike sacs
located Within the alveolar sacs
Respiratory membrane: the
barrier between which gases are
exchanged by alveolar air and
blood (Figure 23-15)
Respiratory membrane
• alveolar epithelium
• capillary endothelium
• their joined basement
Surfactant: a component of the
fluid coating the respiratory
membrane that reduces surface
tension; produced by type II cells
Upper Respiratory Tract Organs – Alveoli
Lower Respiratory Tract Organs – Lungs
FUNCTIONS: air distribution and gas
LOCATION – in the left and right
pleural cavities
The inferior portion of each lung (the
base) rests on the superior surface of
the diaphragm.
• STRUCTURE: cone-shaped
organs extending from the
diaphragm to above the clavicles
(Figure 23-17)
• Hilum: slit on the lung’s
medial surface where the
primary bronchi and
pulmonary blood vessels enter
• Base: the inferior surface of
the lung that rests on the
• Costal surface: lies against
the ribs
Lower Respiratory Tract Organs –
Lobes are further divided into functional units
(bronchopulmonary segments)
Right lung = 10 segments
Left lung = 8 segments
• Left lung is divided into 2 lobes: superior
and inferior
• Right lung is divided into 3 lobes:
superior, middle, and inferior
Lower Respiratory Tract Organs –
• COVERING – visceral pleural
Lower Respiratory Tract Organs –
Thorax (Thoracic Cavity)
FUNCTION: brings about
inspiration and expiration in
respiration by generating pressure
• Pleural divisions: the part
occupied by the lungs
Parietal pleura – lines the entire
thoracic cavity; adheres to the
internal surface of the ribs and
superior surface of the diaphragm;
partitions the mediastinum
• Mediastinum: part occupied by
the esophagus, trachea, large
blood vessels, and heart
Visceral pleura
• Lies against the parietal pleura
Parts of the parietal pleura (parietal pleura
in blue; visceral pleura in purple):
1. costal
2. mediastinal
Image source:
Clinical Correlations
• Pharyngitis – inflammation or
infection of the pharynx (“sore throat”
• Laryngitis – inflammation of the
mucous lining of the larynx,
characterized by edema of the vocal
• “croup” in children under age 5
• Epiglottitis – rare, severe and
rapidly progressing form of
laryngitis (swollen larynx)
• Medical emergency – can cause
airway obstruction
• Tonsillitis – inflammation of one of
more of the masses of lymphatic
tissue embedded in the mucous
membrane of the pharynx
Image source:
Image source:
Clinical Correlations – Anatomical Disorders
• Deviated septum – nasal
obstruction caused by
displacement of the nasal
septum from the midline of
the nasal cavity
• Sleep apnea
• Epistaxis – nosebleed
• Causes - nose blowing,
chronic infection,
inflammation, hypertension,
blow to the nose
• Excellent resource for the thoracic cavity and lungs