Respiratory System
Chapter 21
Structural Anatomy
Upper respiratory system
Lower respiratory system
throat
windpipe
voice box
Function of Respiratory System
• Gas exchange
• Contains receptors for sense of smell
• Filters and warms inspired air
• Produces sound
• Eliminates waste
Gas Exchange
• Intake of O2 and elimination of CO2.
– Cardiovascular involvement?
• 4 steps in respiration (atmosphere ↔ blood ↔ cells)
– Pulmonary ventilation – breathing, inspiration/expiration of air.
– External (pulmonary) respiration – exchange of gases between air
space of lungs and blood in pulmonary capillaries.
– Transport of respiratory gases – transport of gases between the
lungs and body tissues by cardiovascular system.
– Internal (tissue) respiration – exchange of gasses between blood in
systemic capillaries and tissue cells.
Functional Anatomy
• Conducting portion
– “hard tubes”, interconnecting cavities and rigid tubes
that lead to the sites of gas exchange in microscopic
lung tissue.
– Nose, pharynx, larynx, trachea, bronchi, bronchioles
and terminal bronchioles, all serve to conduct air into
lungs.
• Respiratory portion
– “soft spaces”, consists of those portions where the
exchange of gasses occurs.
– Respiratory bronchioles, alveolar ducts, alveolar sacs,
and alveoli, most of lung volume.
The Nose
• Provides:
– air passage
– moistens and warms air
– filters air
– resonating chamber for
sound
– houses olfactory (smell)
receptors.
The Nose
(external and internal portion)
• External nares
– openings
• Nasal bones
– Skeletal framework
provided by nasal
and maxillary bones
• Nasal cartilage
– Flexible plates of
hyaline cartilage
• Lateral, septal, and
alar cartilages
The Nose
(internal portion)
The Nose
(internal portion)
• Nasal cavity – space inside the internal nose, divided into
halves by a vertical petition (septum). Septum formed by
hyaline cartilage, vomer and perpendicular plate.
• Nasal conchae –
subdivide the cavity
into a series of groovelike passages (meatus)
line w/ mucous
membranes.
• Mucous membranes – contain capillaries and epithelial
tissue w/ goblet cells.
Olfactory Receptors
• Olfactory receptors
lie in the superior
portion of the nasal
cavity, olfactory
epithelium.
• Olfactory nerve
communicates with
these recepotrs
through the cribiform
plate of the ethmoid
bone.
Paranasal Sinuses
• Air filled spaces lined w/ respiratory mucosa,
located w/in skull bones.
Paranasal Sinuses
•
•
•
These spaces open into the nasal cavity and are lined with mucous
membranes, and can drain secretions into the nasal cavity.
Inflammation and swelling may cause pressure (sinus headache).
Resonators of the voice sounds.
•
Pharanyx (Throat)
Passage for: 1) food from oral cavity to esophagus and 2) air passing
between nasal cavity and oral cavity to the larynx.
•
Pharanyx (Throat)
3 parts: 1) nasopharynx – swallowing causes uvula and soft palate to
move superiorly to block food from entering this area.
Nasopharynx
• Openings in the nasopharnyx
– Pharyngotympanic tubes (auditory tube), drains the
middle ear.
– Pharyngeal tonsils (adenoids)
Oropharynx
• Oropharynx – intermediate portion of pharynx. Serves as
both passage for air and food.
• Palatine tonsil – pair of tonsils located in faucal wall.
• Lingual tonsil – covers posterior base of tongue.
Laryngopharnyx
•
•
•
Connects esophagus (food tube) with the larynx (voice box), where the
food and airway passage diverge.
It is both a respiratory and digestive pathway.
During swallowing, the food has the “right of way” and air passage is
blocked by the epiglotis in larynx.
The Larynx
• Functions:
– Airway, routes food and air to
proper channel.
– Voice production, voice box.
The Larynx
• The walls are made up of 9 pieces of cartilage.
The Larynx
• 1 thyroid cartilage – prominence (Adam’s apple). Thyroid
gland sits on this triangular piece. Hyoid bone attached to it
via ligaments.
• 1 cricoid cartilage – ring of hyaline cartilage. Landmark for
tracheostomy.
The Larynx
• 1 epiglottis cartilage –acts as trap door over the glottis.
– During swallowing, the larynx rises causing the apparatus to move
down to block liquids and food en route to esophagus.
The Larynx
• 2 arytenoid cartilage – anchors the vocal chords.
– 2 corniculate & 2 cuneiform help in support of vocal folds and lateral
aspects of layrnx.
Voice Production
•
•
•
•
•
Vocal cords are elastic and when air is directed against them they
vibrate.
Pitch is controlled by the tension of the cords, provided by laryngeal
muscles.
Loudness depends on the force of the air across the folds.
Inflammation of the cords can cause laryngitis.
Upper respiratory pathway (pharynx & nasal) responsible for forming
recognizable sounds with help of the paranasal sinuses and muscles in
throat and face help in enunciation of words.
• Tubular passageway located anterior to esophagus,
from the larynx down into the thoracic cavity where
it splits into 2 bronchi.
• Tracheal cartilage – 16-20 C shaped hyaline
cartilage rings.
Trachea
• Opening of cartilage ring pointed posteriorly
which allows for expansion of esophagus as
food passes through.
• Rings also keep the trachea from collapsing
and blocking the airway.
Bronchi and Subdivisions: Bronchial Tree
• A branched airway that leads from the trachea to
the microscopic air sacs in lungs.
• Primary, Secondary and Tertiary Bronchi.
Bronchi and Subdivisions: Bronchial Tree
• Primary Bronchi – trachea divide into left and right
primary bronchi and then enters lung at medial
hilus.
Bronchi and Subdivisions: Bronchial Tree
• Secondary (lobar) bronchi – primary bronchi divide
into secondary bronchi.
• Bronchi undergo successive divisions to create the
bronchial tree, about 23 in all.
Bronchi and Subdivisions: Bronchial Tree
• Tertiary (segmental) bronchi – supplies a portion of
the lung called the bronchopulmonary segment.
• Right lung (largest) is divided into 3 lobes – upper,
middle, and inferior.
• Left lung divided into 2 lobes – upper and lower.
Bronchopulmonary Segments
• Each lobe is separated by C.T. into segments with tertiary
bronchi, veins, and arteries.
Bronchi and Subdivisions: Bronchial Tree
•
•
•
Bronchiole – branches of the segmental bronchi under 1 mm in diameter
that enter the lobes of the lungs.
Terminal bronchiole – branches from bronchiole under 0.5 mm.
This is where the respiratory system begins!
Respiratory Bronchiole
• Respiratory bronchiole – 2 or more branches from each
terminal bronchiole with air sac buds.
• This is the first level of air exchange.
• Alveoli are covered in “cobweb” of pulmonary capillaries.
• Comprises some 70-80 sq. meters.
• Gas exchange is by diffusion through these respiratory
membranes.
• Alveoli are lined with simple squamos epithelium (Type I)
which aid in gas exchange.
• Type II, cuboidal epithelial cells are present and secrete
surfactant to prevent alveoli from sticking together.
Tissue Composition Changes in the
Respiratory Tree
• As branching becomes more extensive in the bronchial
tree there are structural changes….epithelia, cartilage
and smooth muscle changes.
• Epithelia changes – epithelium changes from
psuedostratified ciliated columnar in bronchi to
nonciliated simple cuboidal cells in the terminal
bronchioloes. (macrophages clear debris at this level)
• Cartilage changes – incomplete cartilage rings in
primary bronchi give way to cartilage plates which finally
disappear in the distal bronchioles.
Tissue Composition Changes in the
Respiratory Tree
• Smooth muscle dominates the respiratory zone
– as cartilage decreases, the amount of smooth
muscle increases.
– Contraction of these spiral bands of muscle is
controlled by the ANS and chemicals
(epinephrine relaxes, histamine contracts).
– Muscle layer persists to the end of the
respiratory bronchioles.
– Excessive contraction can close off airways
and create life-threatening event (asthma?)
Lungs and Pleural Cavities
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Lungs are paired, cone shaped, spongy organs located in the thoracic
cavity separated by the heart and mediastinum.
They are enclosed by the diaphragm and thoracic cage.
The bronchi and blood vessels enter medially through the hilus
(depression).
Lung tissue is mostly open space with supporting elastic C.T.
Ventilation
Ventilation
•
•
Muscles of inspiration – diaphragm and external intercostals
Muscles of forced expiration – internal intercostals and abdominal
muscles