The respiratory system
Respiratory System Function
Major Functions
Upper respiratory system:
1. Air conditioning
2. Defense against pathogens
Lower respiratory system:
1. Speech & other respiratory sounds
2. Gas exchange (Supplies body with oxygen and
Disposes of carbon dioxide )
3. Maintenance of homeostasis, e.g. pH
Organs of the Respiratory System
• Divided into:
– Conducting zone – respiratory passage which
serve as conduits that carry air to the sites of gas
exchange
• Serve to filter, humidify, and warm the
incoming air
– Respiratory zone – the actual site of gas
exchange in the lungs
• Respiratory bronchioles, alveolar ducts,
alveolar sacs – contain alveoli
Functional Anatomy of the Respiratory
System
• Respiratory organs
– Nose, nasal cavity, and paranasal sinuses
– Pharynx, larynx, and trachea
– Bronchi and smaller branches
– Lungs and alveoli
THE NOSE
parts:
• Nasal cartilages
• External nose
• Internal nasal cavity
Functions:
• Provides an airway for respiration
• Moistens and warms air
• Filters inhaled air
• Houses olfactory receptors
The External Nose
• Rostral structure protruding slightly from the face
• Size variation due to differences in nasal cartilages.
• The nostrils (cranial nares) are large and widely
spaced.
• The upper part of the opening leads to a blind nasal
diverticulum which occupies the nasoincisive notch.
• The lower part leads to the nasal cavity
– it is essential when passing a stomach tube to ensure that
it is guided into the lower par
The Nasal Cavity
• External nares – nostrils
• Lies in and posterior to the external nose
• Divided by – nasal septum.
• Continuous with nasopharynx
• Internal nares
– posterior nasal apertures (choana)
• Roof – Ethmoid and sphenoid bones
• Floor – hard palate.
The nasolacrimal duct :
- It is an opening found on the floor about 5cm
internal to the entrance near the mucoutaneous
junction
- it has more than one opening
- Ventral nasal meatus.
Nasal Conchae
• Project medially from each lateral wall of the
nasal cavity.
– Dorsal conchae
– Ethmoid conchae
– Ventral conchae
• Creates turbulence which increases the
amount of contact between nasal mucosa and
inhaled air
• Function: to filter, heat and moisten air
Paranasal Sinuses
 The paranasal sinuses are diverticula of the nasal cavity that
excavate the skull bones largely after birth.
 The separation of the inner and outer tables of the bones alters
the conformation of the head
and is specially striking in pigs and cattle, in which certain
sinuses eventually extend dorsal and even caudal to the cranial
cavity.
Paranasal Sinuses
 The sinuses retain their connections with the nasal cavity
 these openings are generally narrow a relatively slow
exchange of air occurs
 The narrowness and locations of the openings make them
prone to blockage when the mucosa is thickened by
inflammation or congestion.
 Not all the sinuses are of equal importance.
The function
 The function of the sinuses is obscure
 Offer some thermal
 Mechanical protection to the orbit and
nasal and cranial cavities
 Enlarge the skull areas available for
muscular attachment without unduly
increasing weight,
 Affect the resonance of the voice.
 All species have frontal and maxillary systems
 neither communicating with its contralateral counterpart.
 The frontal system consists of one or more spaces
within the bones at the border between the nasal and
cranial cavities.
 In most species the various frontal compartments
open separately into ethmoidal meatus in the nasal
cavity
 in the horse the frontal sinus communicates with the nasal
cavity indirectly via the caudal maxillary sinus.
The maxillary sinus system occupies the
caudolateral part of the upper jaw, above the
caudal cheek teeth
 In some species it sends extensions,
variously described as separate sinuses or
as diverticula




into the hard palate
the sphenoid bones
the medial aspect of the orbit
the ventral concha.
 In the horse the maxillary sinus is
divided into caudal and rostral parts,
both connected to the middle nasal
meatus
 In the dog the cavity communicates freely
with that of the nose and is known as the
maxillary recess.
EQUINE
 On each side there are frontal, caudal maxillary, and rostral maxillary sinuses
of importance
 sphenopalatine and ethmoidal spaces of less account.
 the frontal sinus communicates with the nasal cavity indirectly via the caudal
maxillary sinus.
 The two maxillary sinuses together occupy a large part of the upper jaw,
where they have a critically important relationship to the embedded portions
of the caudal cheek teeth.
 They share a slit like communication (nasomaxillary opening) with the middle
meatus of the nasal cavity
 The frontal sinus occupies the dorsal part of the skull medial to the orbit.
 It overlaps both cranial and nasal cavities.
 Since it also occupies the closed part of the dorsal concha, it is more correctly
known as the conchofrontal sinus
BOVINE, OVINE, CAPRINE
 The paranasal sinus system is very poorly developed in the
young calf, Even in the mature animal, the maxillary
compartment continues to adjust to extrusion of the cheek
teeth.
 The complete set of sinuses is very complicated.
It comprises:
1.
2.
3.
4.
5.
Frontal compartments within the bones of the cranial roof and side walls;
Platomaxillary complex within the caudal part of the hard palate and the
face, both before and below the orbit;
Lacrimal sinus within the medial orbital wall;
Sphenoidal sinuses that extend past the orbit into the rostral part of the
cranial floor
Conchal sinuses within the nasal conchae.
The Pharynx
• Funnel-shaped passageway.
• Connects nasal cavity and mouth to the larynx
dorsally and the esophagus ventrally.
• Divided into three locations.
– Nasopharynx, oropharynx, and laryngopharynx
The Nasopharynx
• Superior to the point where food enters
• Only an air passageway
• Closed off during swallowing by soft palate
• Contains the opening to the auditory tube
The Oropharynx
• Posterior to oral cavity, extends from soft
palate to the epiglottis
• Passageway for food and air
The Laryngopharynx
• Dorsal to the larynx and continuous with the
esophagus
• Extends from the epiglottis to the larynx
• Passageway for both food and air
The Larynx (Voice Box)
• Extends from the level of the 2nd to 3th cervical
vertebra
• Cranially attached to the hyoid bone and opens
into the laryngopharynx
• Caudally is continuous with the trachea
• Three functions
– Voice production
– Provides an open airway
– Routes air and food into the proper channels
• The larynx is the part that forms the connection
between the pharynx and the tracheobronchial
tree.
• Position: the larynx can be found behind the
mouth, below the pharynx.
• Its position is altered when the animal swallows
due to its connection with the hyoid apparatus
and tongue.
• The larynx's main function is to protect the rest
of the respiratory tract and system as well as
producing sound (vocalisation)
The Larynx is formed from the following
cartilages
• The Median Epiglottic Cartilage
• The Thyroid Cartilage
• The Cricoid Cartilage
• A Pair of Arytenoid Cartilages
The Musculature of the Larynx
•
•
Extrinsic Laryngeal muscles; these pass
between the larynx and pharynx, tongue, hyoid
bone and sternum.
Intrinsic muscles; connect the laryngeal
cartilages to each other.
–
They are all innervated by the recurrent laryngeal
nerve.
There are 5 muscles:
1.
2.
3.
4.
5.
Cricothyroideus,
Cricoarytenoideus Dorsalis
Cricoarytenoideus Lateralis
Arytenoideus Transversus
Thyroarytenoideus
The hyoid apparatus provides an attachment platform for the tongue and
larynx. Hyoid bones are: stylohyoid (1), epihyoid (2), ceratohyoid (3),
thyrohyoid (4), and basihyoid (5), the latter is the only unpaired hyoid bone.
Thyroid cartilage of the larynx (6), cricothyroideus m. (7), and the trachea
(8).
Right: epiglottic cartilage (1), arytenoid cartilages (2), aryepiglottic fold (3), thyroid cartilage
(4), cricoid cartilage (5), cricoarytenoideus dorsalis m. (6), trachea (7), and root of the tongue
(8).
Left top: The left side of the larynx has been removed. Identify: thyroid cartilage (1),
epiglottic cartilage (2), arytenoid cartilage (3), cricoid cartilage (4), cricoarytenoideus
lateralis m. (5), cricoarytenoideus dorsalis m. (6)
Left bottom: thyroid cartilage (1), cricoid cartilage (2), cricothyroid ligament (asterisk),
cricothyroideus m. (3), trachea (4), basihyoid bone (5), and ceratohyoid bone (6).
The Trachea
• Descends from the larynx through the neck, into
the mediastinum.
• Divides into two main bronchi in the thorax .
• Made up of 35-75 C-shaped cartilage rings of
hyaline cartilage, allow it to be flexible.
• Made of 3 layers of membranes that contain
mucus and help filter the air and allow for
flexibility.
Bronchi in the Conducting Zone
• Bronchial tree – extensively branching
respiratory passageways within the lungs
– Division of the trachea at T4/T7
• Primary bronchi (main bronchi) – largest
bronchi or conduits in the bronchial tree
• Right main bronchi – wider and shorter than
the left and more vertical (clinical important)
Bronchi in the Conducting Zone
• Secondary (lobar) bronchi – each of which supply
one lung lobe
– Three-four on the right, Two on the left
• Tertiary (segmental) bronchi
– Branch into each lung segment
• Overall, 23 orders of air passageways
• Bronchioles – little bronchi, less than 1 mm in
diameter
• Terminal bronchioles – less than 0.5 mm in
diameter
From Bronchi to Lungs
 1 bronchi (enter lungs at hilus, complete
cartilage rings)
 2 bronchi (from now on cartilage plates)
 3 bronchi
 Bronchioles
 Terminal bronchioles
 Respiratory bronchioles
 Alveolar ducts
 Alveolar sacs
Conducting
portion
Respiratory
portion
The Respiratory Zone
• Consists of air-exchanging chambers – called alveoli
• Begins at the terminal bronchioles
• Respiratory bronchioles – branch from terminal
bronchioles, have scattered alveoli protruding from their
walls
– Lead to alveolar ducts – walls consist almost entirely
of alveoli
• Lead to alveolar sacs – terminal clusters of alveoli
• The opening from an alveolar sac into an alveolar
sac is call an atrium “entrance chamber”
The Pleurae
Membranes that cover the lungs and line the pleural
cavity.
• A double-layered sac surrounding each lung
• Parietal pleura
• Visceral pleura
• Pleural cavity - Potential space between the
visceral and parietal pleurae, filled with pleural
fluid
Gross Anatomy of the Lungs
• Each lung roughly cone shaped, in contact with
ribs – costal surface
• Apex – the rounded, cranial tip of the lung
• Base – the concave caudal surface that rests on
the diaphragm
• Hilus – medial indentation
Lungs in the dog
Gross Anatomy of the Lungs
• Lobes – deep fissures separate the lungs into
divisions
• Left lung – 2 lobes
• Right lung – 3-4 lobes
• Lobule – smallest subdivision of the lung seen
by naked eye
• In horses the lungs are elongated and shallow
• The left and right lungs are more equally in size than the
other species
• The difference between left and right manly in thickens
,the right lung more thicker than the left lung and it ha an
accessory lob appended to the base
• There is no evidence of lobation
• The right lung consist of cranial,caudal and accessory
lobes
• The left lung consist of cranial and caudal lobes
• The tow lungs are extensively joined by connective
tissue caudal to the bifurcation of the trachea
• At the junction between the trachea and the bronchi
there are lymph nods which called (tracheobronchial
lymph nodes)
-The pattern in sheep often varies between parts
of the lung some show the connective tissue
septa through the visceral pleura while others
unmarked.
-The lung of cattle possess the usual roughly
pyramidal shape .
Blood Supply and Innervation of the Lungs
• Pulmonary arteries – deliver oxygen-poor
blood to the lungs
• Pulmonary veins – carry oxygenated blood to
the heart
• Innervation
– Sympathetic, parasympathetic, and visceral
sensory fibers
• Parasympathetic – constrict airways
• Sympathetic – dilate airways