Chapter 22 - The Respiratory SystemRespirationInvolves both the respiratory and the circulatory systemsFour processes that supply the body with O2 and dispose of CO2RespirationPulmonary ventilation (breathing): movement of air into and out of the lungsExternal respiration: O2 and CO2 exchange between the lungs and the bloodTransport: O2 and CO2 in the bloodInternal respiration: O2 and CO2 exchange between systemic blood vessels and tissuesRespiratory System: Functional AnatomyMajor organsNose, nasal cavity, and paranasal sinusesPharynxLarynxTracheaBronchi and their branchesLungs and alveoliFunctional AnatomyRespiratory zone: site of gas exchangeMicroscopic structures: respiratory bronchioles, alveolar ducts, and alveoliConducting zone: conduits to gas exchange sitesIncludes all other respiratory structuresRespiratory muscles: diaphragm and other muscles that promote ventilationThe NoseFunctionsProvides an airway for respirationMoistens and warms the entering airFilters and cleans inspired airServes as a resonating chamber for speechHouses olfactory receptorsThe NoseTwo regions: external nose and nasal cavityExternal nose: root, bridge, dorsum nasi, and apexPhiltrum: a shallow vertical groove inferior to the apexNostrils (nares): bounded laterally by the alaeThe NoseNasal cavity: in and posterior to the external noseDivided by a midline nasal septumPosterior nasal apertures (choanae) open into the nasal pharynxRoof: ethmoid and sphenoid bonesFloor: hard and soft palatesNasal CavityVestibule: nasal cavity superior to the nostrilsVibrissae filter coarse particles from inspired airOlfactory mucosaLines the superior nasal cavityContains smell receptorsNasal CavityRespiratory mucosaPseudostratified ciliated columnar epitheliumMucous and serous secretions contain lysozyme and defensinsCilia move contaminated mucus posteriorly to throatInspired air is warmed by plexuses of capillaries and veinsSensory nerve endings triggers sneezingNasal CavitySuperior, middle, and inferior nasal conchaeProtrude from the lateral wallsIncrease mucosal areaEnhance air turbulenceFunctions of the Nasal Mucosa and ConchaeDuring inhalation, the conchae and nasal mucosaFilter, heat, and moisten airDuring exhalation these structuresReclaim heat and moistureParanasal SinusesIn frontal, sphenoid, ethmoid, and maxillary bonesLighten the skull and help to warm and moisten the airPharynxMuscular tube that connects to theNasal cavity and mouth superiorlyLarynx and esophagus inferiorlyFrom the base of the skull to the level of the sixth cervical vertebraNasopharynxAir passageway posterior to the nasal cavityLining: pseudostratified columnar epitheliumSoft palate and uvula close nasopharynx during swallowingPharyngeal tonsil (adenoids) on posterior wallPharyngotympanic (auditory) tubes open into the lateral wallsOropharynxPassageway for food and air from the level of the soft palate to the epiglottisLining of stratified squamous epitheliumIsthmus of the fauces: opening to the oral cavityPalatine tonsils in the lateral walls of faucesLingual tonsil on the posterior surface of the tongueLaryngopharynxPassageway for food and airPosterior to the upright epiglottisExtends to the larynx, where it is also continuous with the esophagusLarynxAttaches to the hyoid bone and opens into the laryngopharynxContinuous with the tracheaFunctionsProvides a patent airwayRoutes air and food into proper channelsVoice productionLarynxCartilages of the larynxHyaline cartilage except for the epiglottisThyroid cartilage with laryngeal prominence (Adam’s apple)Ring-shaped cricoid cartilagePaired arytenoid, cuneiform, and corniculate cartilagesEpiglottis: elastic cartilage; covers the laryngeal inlet during swallowingLarynxVocal ligamentsAttach the arytenoid cartilages to the thyroid cartilageContain elastic fibersForm core of vocal folds (true vocal cords)Opening between them is the glottisFolds vibrate to produce sound as air rushes up from the lungsLarynxVestibular folds (false vocal cords)Superior to the vocal foldsNo part in sound productionHelp to close the glottis during swallowingVoice ProductionSpeech: intermittent release of expired air while opening and closing the glottisPitch is determined by the length and tension of the vocal cordsLoudness depends upon the force of airChambers of pharynx, oral, nasal, and sinus cavities amplify and enhance sound qualitySound is “shaped” into language by muscles of the pharynx, tongue, soft palate, and lipsLarynxVocal folds may act as a sphincter to prevent air passageExample: Valsalva’s maneuverGlottis closes to prevent exhalationAbdominal muscles contractIntra-abdominal pressure risesHelps to empty the rectum or stabilizes the trunk during heavy liftingTracheaWindpipe: from the larynx into the mediastinumWall composed of three layersMucosa: ciliated pseudostratified epithelium with goblet cellsSubmucosa: connective tissue with seromucous glandsAdventitia: outermost layer made of connective tissue that encases the C-shaped rings of hyaline cartilageTracheaTrachealis muscleConnects posterior parts of cartilage ringsContracts during coughing to expel mucusCarinaLast tracheal cartilagePoint where trachea branches into two bronchiBronchi and SubdivisionsAir passages undergo 23 orders of branchingBranching pattern called the bronchial (respiratory) treeConducting Zone StructuresTrachea  right and left main (primary) bronchiEach main bronchus enters the hilum of one lungRight main bronchus is wider, shorter, and more vertical than the leftEach main bronchus branches into lobar (secondary) bronchi (three right, two left)Each lobar bronchus supplies one lobeConducting Zone StructuresEach lobar bronchus branches into segmental (tertiary) bronchiSegmental bronchi divide repeatedlyBronchioles are less than 1 mm in diameterTerminal bronchioles are the smallest, less than 0.5 mm diameterConducting Zone StructuresFrom bronchi through bronchioles, structural changes occurCartilage rings give way to plates; cartilage is absent from bronchiolesEpithelium changes from pseudostratified columnar to cuboidal; cilia and goblet cells become sparseRelative amount of smooth muscle increasesRespiratory ZoneRespiratory bronchioles, alveolar ducts, alveolar sacs (clusters of alveoli)~300 million alveoli account for most of the lungs’ volume and are the main site for gas exchangeRespiratory Membrane~0.5-m-thick air-blood barrierAlveolar and capillary walls and their fused basement membranesAlveolar wallsSingle