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Respiratory Anatomy and Physiology Parsa& AmeliaDisclaimer • UoMCTSSisnotaffiliatedwithUniversityofManchester MedicalSchoolandtheInformationprovided bythe committeeandthelecturesare aimedtoaid studentsin theirlearningandinnoshapeorform shallreplacethe officiallecturesandlearningmaterialsfromtheMedical School • Enquiries:@uomctsson instagramBonyanatomy-ribs FIRSTRIB TYPICAL RIBS (3-9) ATYPICAL RIBS (1,2,10,11,12) - 2ndrib- thinner& longerthanrib 1.Has 2articular facets. Alphabetically, head, tubercle, scalenetubercle Head- 2 articular facets - 10th,11th&12thribs- only have D- groovefor subclavianartery Tubercle- articulateswith onefacet.Articulatewithasingle E- groovefor subclavianvein transverseprocess vertebra. Groove-intercostalVAN(superior Ribs11 and12have nonecksor Is theshortestand widest rib toinferior) tubercles! Onlyhas onefacetfor articulation withT1 Not coveredbut important: vertebraandfeatures,sternum, scapula,costalcartilages Surfaceanatomy&PIPPAsites Lobe Left lung Right lung Upper ANTERIOR:Above clavicle&Ribs2-4 ANTERIOR:Above clavicle&Ribs2-4 POSTERIOR:abovethescapular spine POSTERIOR:abovethescapular spine Middle N/A ANTERIORONLY: ribs 4-6 Lower ANTERIOR:ribs 6-8 ANTERIOR:ribs 6-8 POSTERIOR:T8-T10 POSTERIOR:T8-T10 *LATERALLY*: ribs6-8 midaxillary line *LATERALLY*: ribs6-8 midaxillary lineDiaphragm - Cavalopening VenaCava(8 letters,T8),rightphrenicnerve High - Aortichiatus yield! 12 letters,T12.Aorta,thoracicduct,azygousvein - Oesophagealhiatus - Oesophagus(10 letters,T10),R+L vagusnerves, Peripheralpart made ofskeletalmuscle anda centraltendinous part Innervation: Phrenicnerve- sensoryand motor (C3-C5keepsthe diaphragm alive!) Intercostalnerves- peripheralsensory Lungstuff! Impressions! Learn acouple for each lung andknow roughly where you'd expect to see them. Left lung Right lung Descendingaorta Oesophagus Aorticarch IVC Subclavianarteries Azygousarch - Bronchusis alwaysposterior - Veins areanterior and inferior Not coveredbut important: transversesections-very - Arteriesareanterior superior highyieldbut unfortunatelyvery timeconsuming! Mediastinum- willcoverincardiacweek! Cartilage! Mainbronchi- completerings Morelungstuff.. Smaller/segmentalbronchi- crescent shape Bronchioles- nocartilage • Flow of air: Trachea, bronchus, lobar bronchi, segmental bronchi, conducting bronchioles, terminal bronchioles, respiratory bronchioles Trachea: ciliated pseudostratifiedcolumnar epitheliumwithgobletcells Bronchi/bronchioles: do not havegoblet cells, insteadhaveclubcells- secretesurfactantChestX-Rays:Imagequality&orientation • First,is thisAP orPA?Whatarethedifferences?ChestX-Rays:Identifyingstructures Physiologyof therespiratorysystem ParsaInspirationandExpiration • Airwillonly flowfroma regionof high pressuretoaregionoflow pressure • expiration: • chest contracts • inspiration: • chestexpands • Its volume decreases. • same amount of air in smaller • Its volumeincreases. volume = higher pressure • sameamountofairinbiggervolume = • ∴ air pressure higher IN lowerpressureofair thorax than OUT side therefore air moves • ∴ lowerpressureairIN thoraxthanOUTside from INside to OUTside thoraxsoairmovesfromOUTside(high pressure)toINside(low pressure)IntrathoracicandIntrapleuralpressures • Lungs have the tendency to collapse (due to elastic recoil explained later) oThinkofyourlungsasballoonsPressurechanges • During tidalbreathing: - Intrpleural pressure=-4mmHg - Alveolar pressuredecreasesaswe inhale so aircomes inand increasesasweexhaleto pushthe airout - Intrapleural pressurealwaysremainsnegative: o During inspiration,thoraciccavity expands,increasingthevolume of pleural cavity-> decreaseinitspressure(-4to –8) o Expiration, thoraciccavitycontracts, decreasingpleural cavity,increasein intrapleural pressurebut stillnegative(-8 to–4)Mechanicsofventilation:Inspiration • Active process (opposite to naturalrecoil during expiration) • Normal or Quiet inspirationMechanicsofventilation:Inspiration • Forced Inspiration• Asdiaphragms flattens, lungs' inferior edges move down into the opened costodiaphragmatic recess.Mechanicsofventilation:Expiration • Quiet expiration – passive: • By Elastic/Lung recoil • The connective tissue of the lungs contains elastic fibres and the alveoliare lined with afilm of fluidwhich has surface tension. • Water molevules pullon each other and pullthe alveoli wallswith them • Causing the alveolito recoil and become smaller • intrapleural pressure (as we spoke about earlier)nt and • So mechanism...Mechanicsofventilation:Expiration • Forced expiration – active: • Alongside the elastic recoil (and diaphragm relaxation), muscles of expiration help • Muscles of expiration: • Internal intercostals oDepressthe ribs(andthereforesternum)anddecreasethe APvolume of lungs • Abdominal recti muscles oThey pull downwardonthelowerribsat thesametime thatthey andother abdominal muscles alsocompresstheabdominal contentsupward againstthediaphragmControlofventilation:Nervous Respiratory centreis divided intothreemajor collections ofneurons: (1) DRG in the dorsal medulla - mainly causes inspiration (2) VRG in theventrolateral medulla - mainly causes expiration (3) thepneumotaxiccenter,dorsally in the superior pons - mainly controls rate and depthof breathing.DRG • Determines basicrhythmof breathing • Causescontraction ofdiaphragm andexternal intercostals - Controlsphrenicnerve - >diaphragm - Intercostalnervesto EXTERNALintercostalssince DRGcontrols inspiration - No Sternocleidomastoidsclesthatwespokeabout o Scalenemuscles o Pectoralisminor o SerratusanteriorVRG • areasas: Inspiratory and Expiratory • Inactive during normal quiet breathing • Inspiratory areas activated byDRG during forceful breathing to innervate accessory muscles to aid forced inspiration. • Involved in Forced expiration • Causes contraction of internal intercostals and abdominal musclesRampSignal • The medullaryrespiratory center stimulatesbasic inspiration for about 2 seconds and then basic expiration for about 3 seconds (5sec/breath= 12breaths/min).PneumotaxicandApneusticcentres • Both in Pons • Stimulatesinspiratory area of medullato prolong inhalation – DRG • Inhibits Apneustic area (and DRG) to stop inhalation • Breathing is more rapid when pneumotaxic area is activeHering-Breuerinflationreflex • There are stretch receptors in the wallof bronchi and bronchioles • When lungis overstrectched during inspiration • Afferents sent bythese to DRG through Vagusnerve • Similareffect as the pneumotaxic centre • Stops further inspiration • Just like the pneumotaxic centre, this increases the rate of respirationControlofventilation:Chemical • Peripheralchemoreceptors->aorticand carotidbodies • Mainideais increasedventilation • 2 thingscanhappen: • DecreasearterialO2 (hypoxia) • IncreasearterialCO2 (hypercapnia) • Detection->afferentssenttorespiratory centres->increasedventilation -> decreaseCO2, increaseO2 • Afferents:glossopharyngealnerve(from (fromtheaorticbodies)hevagus nerveControlofventilation:Chemical • Central chemoreceptors -> medulla • CO2 can cross the BBB but H+ ions can not cross the BBB • CO2 reacts with water to form H+ ions • Then H+ ions act on the central chemoreceptors • In hypercapnia there is a lot of CO2 therefore a lot of H+ in brain CSF therefore stimulation of these chemoreceptors and increased ventilation bythe same mechanism of previous slideLungVolumesandCapacities • Volume: different measurable quantities of air within the lungs atspecific points during the respiratory cycle • Capacity:two or more volumesThankyou • Any Questions? • amelia.websdale@student.manchester.ac.uk • parsa.mousazadeh@student.manchester.ac.uk • Insta:@UoMCTSS