Presentation on theme: "Respiratory System The University of Nottingham"— Presentation transcript:
1Respiratory System The University of Nottingham School of Veterinary Medicine and ScienceCreated by Chloe HughesVeterinary Student
2Nares (nostrils)The nares are surrounded by hairless skin and supported by nasal cartilagesSpecies differences:Carnivores: a nasal plate that is divided by a medium groove called the philtrum.Bovine: a nasolabial plate that has cornified stratified epithelium and serous glandsEquine: have an incomplete cartilaginous ring allowing distensible nostrilsAvian: slit-like openings with an overhanging operculum.Porcine: snout contains os rostrale (bone)
3Upper Respiratory System Consists of the nasal cavity, paranasal sinuses, nasopharynx and larynx.Functions: heating/moistening air and defence against incoming particles.Nasal CavityNasopharynxHard PalateOesophagusOropharynxLarynxOral CavityTracheaTongueLaryngopharynxEpiglottisSoft Palate
4Nasal Cavity Paired chambers separated by a nasal septum. Connected anteriorly to the nares and posteriorly to the nasopharynx through choanae.Divided into meatus by nasal conchae that consist of turbinate bone and the covering respiratory mucosa (pseudostratified columnar epithelium and the underlying lamina propria)Allows a defence (sneeze reflex and cilia) and warming and moistening functionDorsal conchaeCaudal conchaeVestibuleChoanaeVentral conchae
5Nasal Cavity The nasal conchae divide the nasal cavity into meatus. Dorsal meatusMiddle meatusVentral meatusCommon meatusNasal SeptumThe nasal conchae divide the nasal cavity into meatus.In the horse:Dorsal meatus leads to the olfactory mucosaMiddle meatus leads to the paranasal sinusesVentral and the common meatus lead to the pharynxThe nasal cavity anatomy is fairly simple in horse compared to the complex structure of the canine nasal cavity.
6Vomeronasal OrganIn addition to the olfactory cells at the end of the dorsal meatus, there is also an accessory olfactory structure, the vomeronasal organ.The vomeronasal organ consists of paired blind ending ducts contained within the hard palate. It connects the nasal and oral cavities and contains unique chemoreceptors.Functions:Pheromone detectionFlehmen responseVomeronasal Organ
7Paranasal Sinuses Frontal sinus Sphenopalatine sinus 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 sinusesBirds have an infraorbital sinus below the eyeFrontal sinusSphenopalatine sinusRostral maxillary sinusCaudal maxillary sinus
8PharynxThe 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.NasopharynxLaryngopharynxOropharynx
9Eustachian tube and Guttural Pouch The Eustachian tube connects the nasopharynx to the middle ear. In the horse, an out pouching forms the guttural pouch. The guttural pouch is approximately a cm³ 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.
10LarynxThe 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.Functions:PhonationSwallowingBreathingIt 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
11Larynx and Hyoid Apparatus Equine larynx and hyoid apparatusArytenoid cartilageEpiglottisStylohyoidEpihyoid (vestigial)Cricoid cartilageCeratohyoidThyrohyoidBasohyoidThyroid cartilage
12EpiglottisThe epiglottis channels food towards the epiglottis during swallowing, preventing ingesta entering the lungs through the tracheaThe 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.
13Lower Respiratory System The lower respiratory system consists of the trachea down to the alveoli.Functions:Gas exchangeMetabolic functions (surfactant synthesis, histamine synthesis, activation of angiotensin)Body temperature regulationAcid-base regulationVocalisationConsists of two types of airways:Conducting – carry, warm, filter and saturate air going to respiratory airwaysRespiratory – undergo gaseous exchange
14Lungs The lungs obtain their appearance through the deep fissures. Canine:the right lung is larger and is divided into cranial, middle, caudal and accessory lobes.The left lung is divided into a cranial and caudal lobe.Equine:The lungs are more equal in size.There is no external lobation other than the accessory lobe of the right lung.Bovine:The right lung is significantly larger than the leftThe left lung is divided into a cranial and caudal lobe, with the cranial further divided into two parts.The right lung is divided into cranial, middle, caudal and accessory lobes
15Lower Respiratory System TracheaBronchusBronchioleConducting SystemRespiratory BronchioleAlveolar ductAlveolar sacAlveolusRespiratory SystemFallow deer lung castNB. The upper respiratory system is also part of the conducting system
16Trachea Flexible tube held open by cartilaginous c-shaped rings Rings are joined by connective tissueTrachealis muscle runs along the dorsal aspectlined by ciliated columnar epithelium that functions as a ‘mucociliary escalator’Mucus traps small particles which are moved towards the pharynx by the cilia, removing debris from the lungs.Various goblet cells line the trachea, producing the mucous coat.Cartilaginous C- shaped rings
18Conducting System Bronchi Lined by pseudostratified epithelium and goblet cellsDeveloped spiral bands of bronchial smooth muscle regulate the volume of the conducting zoneOutside the smooth muscle are irregular plates of bronchial cartilageSurrounded by a highly vascular peribronchial sheath that contains lymphatic vesselsBronchioleThe epithelium is reduced to cuboidal with no mucus secreting glandsAlthough cartilage is absent, the spiral bronchial muscle is well developed in this regionThere is collateral ventilation (connections) between bronchioles, making them less vulnerable to blockageLacks the vascular sheath
19Conducting System Bundles of smooth muscle Cartilage (hyaline) BronchusBlood vessel
20Respiratory System Respiratory Bronchiole: Has a few alveolar scattered along its wallLined by typical bronchiolar epithelium, but changes to simple squamous at alveolus entranceThe alveoli entrance is guarded by bronchial smooth muscleAlveolar duct:Have alveoli on its walls with the openings guarded by smooth muscleAlveolar sac:Usually there are clusters of alveolar sacs on the end of the alveolar ductAlveolus:Minute polygonal chambers whose diameter changes with breathingThe wall is a thin irregular sandwich with the two outer surfaces formed by epithelial cells and an inner network of capillaries
22Thoracic cavity and pleura Intercostal muscles:External – run in a caudoventral direction and are responsible for inspirationInternal – run in a caudodorsal direction and consists of 2 components: the interosseus, responsible for expiration, and interchondral, responsible for inspiration.Pleura:A serous membrane lining the contents of the thoracic cavityConsists of a single layer of flat epithelium and underlying propriaThe thoracic cavity is lined by parietal pleura.Each lung is covered in visceral pleura, arranged as closed pleural sacs.The space between the right and left pleural sacs is the mediastinumThe narrow space between the parietal and visceral pleura is the pleural cavity. This is under sub-atmospheric pressure.
23Diaphragm Muscular part Tendinous part A dome shaped structure separating the thoracic and abdominal cavities.Convex on its cranial surface.Has a muscular peripheral part and a tendinous central area.Muscular part has sections arising from the xiphoid process of sternum, vertebral column and caudal ribs.Supplied by the phrenic nerveDuring inspiration, the diaphragm contracts to increase the volume of the thoracic cavity, thus decreasing its pressure to draw air in.Vice versa occurs for expiration with the diaphragm relaxing.
24Avian Respiratory Tract The avian tract differs in the following ways:A choana (opening) connecting the nasal and oral cavityThe larynx does not have an epiglottis, so muscles constrict, closing the glottis, to allow passage of foodThe trachea is longer and wider than in mammals, and consists of interlocking rigid cartilages.A syrinx is located at the trachea bifurcation and is responsible for sound productionAir sacs, acting as bellows, may store air during respiration, allowing the lungs to be constantly supplied by fresh air.The lungs are stiffer and do not expand like mammalian lungs due to more cartilage being presentThere is a counter current exchange in the lungs of the bird, allowing for efficient exchangeBirds experience a continuous unidirectional air flow through the lungsParabronchi