Respiratory

• RESPIRATORY SYSTEM: the connected structures from the nostrils and oral cavity to and including the lungs. It is subdivided at the cranial end of the larynx into upper and lower respiratory tracts. The major function of the respiratory tract is transport and exchange of gaseous oxygen and carbon dioxide into and out of the blood. Oxygen is utilized by the cells for metabolism. Carbon dioxide is the resulting waste product.
• NOSE


  The external nose, its associated cartilage, and the nasal cavity
• The respiratory system is a portal of entry into the body and must be guarded. The tonsils of the pharynx are one part of this protective system. The upper respiratory tract, nasal cavity, and nasopharynx optimally warm or cool the gases brought into the body. Hairs associated with the nares filter out large particles. Smaller particles get stuck in the lining mucosa. Many ciliated lining cells drive the mucous coat back to the oral cavity for elimination.
• Phonation


  Production of sound caused by movement of air across the vocal folds, causing them to vibrate. The associated resonance, changed and modified by the tongue, oral cavity, mouth and lips, produces characteristic sounds.
• Olfaction


  The sense of smell, perceived in the brain (cerebral cortex), involves receptors (olfactory nerve, CN I) located in the nasal cavity. Gaseous material and airborne particles are inhaled and detected (smelled) once dissolved in the mucous coat lining the nasal cavity.
• Heat regulation


  By panting, the dog helps control body temperature via evaporation. The lungs also play a role in acid-base
• External nose


  The rostral structure protruding slightly from the face.
• Philtrum


  The groove in the lip and middle of the nose separating the nostrils.
• Nostrils (cranial nares)


  The external openings into the nasal cavity, thus, the respiratory system.
• Bony nasal aperture


  The rostral ends of the nasal bones and the incisive bones, referred to as the immovable nose. The nasal cartilages extend from the opening rostrally.
• Movable portion of the nose

  The nasal cartilages, their ligaments and skin coverings.
• Cartilage of the nose


  The structures giving the nose its characteristic appearance. The nasal cartilages project rostrally from the bony nasal aperture.
• Philtrum: deep in the carnivores and small ruminants; shallow or absent in the pig, ox and horse.
• NASAL CAVITY


  The facial portion of the respiratory tract extending from the nostrils to the caudal nares. It is divided into halves by the median nasal septum. The nasal cavity can be divided into three parts. The vestibule is the rostral part just inside the nostril. The middle part is filled with nasal conchae. These are thin scrolls of bone covered by mucous membrane. Passages between the conchae are called meatuses (meatus). The caudal part contains the numerous ethmoturbinates. The nasal cavity is connected to the paranasal sinuses (pg. 56) and the nasopharynx.
• Median nasal septum


  The perpendicular partition separating the nasal cavity into left and right halves. It is composed of bony (vomer, nasal and ethmoid bones), cartilaginous, and membranous parts. Its cranial cartilaginous part expands laterally, forming the nasal cartilages for each nostril.
• Ventral nasal concha


  The extensively folded structure filling the middle lumen of the nasal cavity. It is a separate and distinct bone of the skull.
• Ethmoidal conchae

  The delicate, mucosa-covered, bony scrolls known as ethmotubinates filling the caudal part of the nasal cavity. They are part of the ethmoid bone.
• Dorsal nasal concha


  The upper concha extending from the ethmoid bone's cribriform plate to the rostral nasal cavity.
• Nasal conchae

  The bony scrolls covered by nasal mucosa that fill each half of the nasal cavity. With the median nasal septum, they divide the cavity into passageways (meatuses).
• Nasal meatus

  The passageways between the conchae of each half of the nasal cavity.
• Dorsal nasal meatus

  The narrow passageway between the dorsal nasal concha and the nasal bones leading into the caudal nasal cavity.
• Middle nasal meatus


  The passageway between the dorsal nasal concha and the ventral nasal concha leading into the caudal nasal cavity.
• Common nasal meatus


  The narrow vertical space between the median nasal septum and the conchae, from the roof to the floor of the nasal cavity. Laterally it is continuous with the other meatuses.
• Ventral nasal meatus


  The largest meatus located between the ventral nasal concha and the hard palate. It leads directly into the nasopharynx.
• Nasopharyngeal meatus


  The short passageway connecting the ventral nasal meatus with the caudal naris (choana) on each side.
• Caudal nares or choanae

  The two openings of the nasopharyngeal meatus into the nasopharynx, separated by the vomer bone.
• Nasal diverticulum ("false nostril"): the dorsal passage through the horse's nostrils into a blind cutaneous pouch. When "tubing" a horse, a thumb placed in the diverticulum will aid in directing the tube into the ventral nasal meatus.
• Rostral bone (os rostrale) (pg. 52,1): the bone in the nose of a pig to help it "root".
• "Nasogastric tubing" in horses: the passage of a stomach tube through the nasal cavity, pharynx, and esophagus to the stomach. The tube must be passed through the ventral nasal meatus, nasopharyngeal meatus, and caudal nares to reach the pharynx and the esophagus. Passing the tube in the dorsal or middle nasal meatus would lead into the ethmoturbinates and cause massive hemorrhage.
• Rhinitis: inflammation of the nasal cavity.
• Epistaxis: bleeding from the nose.
• Dyspnea: difficult breathing.
• Ethmoid hematoma horses: hematoma of the mucosa lining ethmoid conchae, resulting in intermittent epistaxis.
• Pharyngeal lymphoid hyperplasia: disease of young horses resulting in cough and pharyngeal pain.
• "Strangles", horse distemper: Streptococcus equi infection of horses causing abscesses and swelling of lymph nodes (submandibular and retropharyngeal). Untreated horses sound like they are strangling, hence the name.
• "Bastard strangles": metastasis of S. equi to other organs (lungs, mesentery, liver, spleen, kidney and brain).
• Dorsal displacement of the soft palate - horse: the soft palate is on top of the epiglottis, resulting in exercise intolerance due to the soft palate being drawn into the larynx during inspiration. Normally the epiglottis overlaps the dorsal side of the soft palate.
• Epiglottic entrapment - horse: displacement of subepiglottic tissue over the epiglottis resulting in exercise intolerance. Endoscopic examination through the nose can differentiate entrapment from displacement. In entrapment the margins of the epiglottis, but not the epiglottis itself are obscured, in displacement the epiglottis is obscured.
• "Summer snuffles", Allergic rhinitis: type I hypersensitivity in cattle resulting in dyspnea and intense pruritis (itching).
• "Rednose": hyperemia of the muzzle in cattle due to infectious bovine rhinotracheitis (IBR) virus.