R espiratory System. The University of Nottingham School of Veterinary Medicine and Science Created by Chloe Hughes Veterinary Student. Nares (nostrils). The nares are surrounded by hairless skin and supported by nasal cartilages Species differences:
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The University of Nottingham
School of Veterinary Medicine and Science
Created by Chloe Hughes
The nares are surrounded by hairless skin and supported by nasal cartilages
Consists of the nasal cavity, paranasal sinuses, nasopharynxand larynx.
Functions: heating/moistening air and defence against incoming particles.
The nasal conchae divide the nasal cavity into meatus.
In the horse:
The nasal cavity anatomy is fairly simple in horse compared to the complex structure of the canine nasal cavity.
Air filled sinuses connected to the nasal cavity through the middle meatus. Functions include resonating (voice), insulation and cooling of the brain and light weight skull construction. The frontal and maxillary sinuses are common to all species.
The frontal sinus drains into the ethmoidal meatus (except in the horse).It has a rostral and caudal part, with the caudal part communicating with horn in cattle.
Maxillary sinus is divided into two compartments and drains into the middle meatus.It contains the cheek teeth (molars and premolars).
Cattle have palatine, sphenoid, lacrimal and palatomaxillary sinuses
Birds have an infraorbital sinus below the eye
Rostral maxillary sinus
Caudal maxillary sinus
The pharynx connects the oral cavity and nasal cavity to the trachea and oesophagus. It functions as a passageway for air and food but also as a resonating chamber. It is split into three regions, the nasopharynx, oropharynx and laryngopharynx.
The Eustachian tubeconnects the nasopharynx to the middle ear. In the horse, an out pouching forms the guttural pouch. The guttural pouch is approximately a 300-500cm³ space in the equine skull, between the skull base, atlas, pharynx and oesophages.It is divided into medial and lateral compartments by the stylohyoid bone. It functions in cooling of the blood entering the brain.
The larynx is a structure connecting the pharynx to the trachea and oesophagus. It is suspended by the hyoid bones that articulate with the base of the skull.
It consists of hyaline and elastic cartilages: cricoid, thyroid, epiglottis and 2 arytenoid cartilages.
The larynx contains the vocal cords required for phonation.
In birds, the larynx consists of only cricoid and arytenoid cartilages. It does not have vocal folds therefore sound is created by the syrinx at the tracheal bifurcation
Equine larynx and hyoid apparatus
The epiglottis channels food towards the epiglottis during swallowing, preventing ingesta entering the lungs through the trachea
The larynx, and most of the epiglottis, is lined with stratified squamous epithelium up to the vocal cords . The rest of the larynx is lined by pseudostratified columnar epithelium, like the respiratory tract.
The lower respiratory system consists of the trachea down to the alveoli.
Consists of two types of airways:
The lungs obtain their appearance through the deep fissures.
Fallow deer lung cast
NB. The upper respiratory system is also part of the conducting system
Cartilaginous C- shaped rings
Bundles of smooth muscle
The avian tract differs in the following ways: