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HistologyHistologyof theof the

RespiratoryRespiratory

SystemSystemMa. Minda Luz M. Manuguid, M.D.Ma. Minda Luz M. Manuguid, M.D.


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The Respiratory TractThe Respiratory Tract


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The Respiratory TractThe Respiratory Tract

Conducting PortionConducting Portion -- nasal passages,nasal passages,nasopharynx, larynx, trachea, bronchi,nasopharynx, larynx, trachea, bronchi,

bronchiolesbronchioles *epithelium (mucosa):*epithelium (mucosa):

pseudostratified columnar ciliatedpseudostratified columnar ciliated

Respiratory PortionRespiratory Portion -- respiratoryrespiratorybronchioles,bronchioles, alveolar ducts, alveolar sacs,alveolar ducts, alveolar sacs,

alveolialveoli

*epithelium:*epithelium: simple squamoussimple squamous


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Respiratory EpitheliumRespiratory Epithelium


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Nasal cavitiesNasal cavities

External naresExternal nares - watery, filtering- watery, filteringsecretionssecretions & mucinous secretions& mucinous secretions

vibrissaevibrissae- large, short coarse hairs- large, short coarse hairs Nasal conchae/turbinatesNasal conchae/turbinates - superior,- superior,

inferior, & middle plates of scallopedinferior, & middle plates of scallopedbonebone projecting into the nasal cavityprojecting into the nasal cavity

- induce turbulent airflow to trap- induce turbulent airflow to trapdebrisdebris

Extensive vascular bedExtensive vascular bed - warms, cools,- warms, cools,

&& moistens airmoistens air


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Nasal glandsNasal glands


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Olfactory EpitheliumOlfactory Epithelium

Olfactory epitheliumOlfactory epithelium -- upper posteriorupper posteriorportion ofportion of nasal cavities, just lateral tonasal cavities, just lateral tothe nasal septum:the nasal septum:

Bowmans glandsBowmans glands -- serous secretionsserous secretions

moistenmoisten mucosa & bathe the olfactorymucosa & bathe the olfactorycellscells

Olfactory cellsOlfactory cells bipolar neurons with verybipolar neurons with verylonglong nonmotile cilia; containnonmotile cilia; contain

chemoreceptorschemoreceptors;; axons grouped intoaxons grouped into filafilaolfactoriaolfactoria that penetrate the cribriformthat penetrate the cribriformplate of the ethmoid bone to the olfactoryplate of the ethmoid bone to the olfactorylobe of the CNSlobe of the CNS

Sustentacular cellsSustentacular cells have apical microvillihave apical microvilli


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Olfactory epitheliumOlfactory epithelium Olfactory CellsOlfactory Cells (red(red

arrow) - bipolar neuronsarrow) - bipolar neuronsthat span the entire lengththat span the entire lengthof the epithelium, provideof the epithelium, provide

the sense of smell; nucleithe sense of smell; nucleican usually be found in thecan usually be found in themiddle of the epitheliummiddle of the epithelium

supportivesupportiveSustentacularSustentacularcellscells ((blue arrow) - provideblue arrow) - provide

mechanical and metabolicmechanical and metabolicsupport to the olfactorysupport to the olfactorycells; nuclei are usually thecells; nuclei are usually themost superior ones,most superior ones,(closest to the lumen) .(closest to the lumen) .

Basal CellsBasal Cells

(green arrow)(green arrow)

- cells that will give rise to- cells that will give rise to


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NasopharynxNasopharynx

connects nasal cavities to the Larynx;connects nasal cavities to the Larynx;

abuts the oropharynxabuts the oropharynx

Epithelium is mostlyEpithelium is mostly pseudostratifiedpseudostratifiedcolumnarcolumnar, with patches of, with patches ofstratifiedstratified

squamoussquamous, esp. in lower pharynx &, esp. in lower pharynx &

epiglottisepiglottis

Pharyngeal tonsilPharyngeal tonsil ((adenoidadenoid) ) dorsomedialdorsomedial


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LarynxLarynx

GlottisGlottis - laryngeal aperture- laryngeal aperture Vocal folds/cordsVocal folds/cords - folds of laryngeal- folds of laryngeal

mucosa on either side of the glottis:mucosa on either side of the glottis:

upper ventricular (false) & lowerupper ventricular (false) & lowercaudal (true)caudal (true) Laryngeal ventriclesLaryngeal ventricles - deep recesses- deep recesses

between cranial & caudal vocal foldsbetween cranial & caudal vocal folds LiningLining:: stratified squamousstratified squamous on upperon upper

surface, epiglottis, & vocal folds;surface, epiglottis, & vocal folds;

the rest -the rest -pseudostratified columnarpseudostratified columnar

ciliatedciliated


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The LarynxThe Larynx


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LarynxLarynx


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LarynxLarynx Hyoid boneHyoid bone - caps- caps

the laryngeal bodythe laryngeal body

EpiglottisEpiglottis - ventral- ventral

rimrim LaryngealLaryngeal

cartilagescartilages hyaline hyaline

& elastic& elastic

Mucous glandsMucous glands --

especiallyespecially

abundant in theabundant in the

ventricular foldsventricular folds


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Laryngeal cartilagesLaryngeal cartilages

Thyroid cartilageThyroid cartilage - s -- s -anterior, large, broad,anterior, large, broad,shield-like, hyalineshield-like, hyalinecartilagecartilage

ArytenoidArytenoid p - upper p - upperdorsal hyaline & elasticdorsal hyaline & elastic

CorniculateCorniculate p - upper p - upperdorsal, elastic cartilagedorsal, elastic cartilage

CuneiformCuneiform p - form p - formthe rim of the larynx,the rim of the larynx,elasticelastic

CricoidCricoid s - circular, s - circular,hyaline, on top of tracheahyaline, on top of trachea


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Larynx: the Voice BoxLarynx: the Voice Box

The muscles inserting onto the outside wall canThe muscles inserting onto the outside wall canchange the shape of the box, and in so doingchange the shape of the box, and in so doingchange the tension and vibration frequencies of thechange the tension and vibration frequencies of the

vocal folds.vocal folds. Air being moved through from the depths of theAir being moved through from the depths of the

respiratory system causes the vibration to occur.respiratory system causes the vibration to occur. Overtones, harmonics, and other sounds are addedOvertones, harmonics, and other sounds are added

by the echoes produced in the chest cavity, theby the echoes produced in the chest cavity, the

tongue, the teeth, and the oral cavity.tongue, the teeth, and the oral cavity. PhonationPhonation involves distortion of the shape so thatinvolves distortion of the shape so that

the vocal folds at the cranial end vibrate at differentthe vocal folds at the cranial end vibrate at differentrates and produce different tones.rates and produce different tones.


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TracheaTrachea

MucosaMucosa Goblet cellsGoblet cells -- apical microvilli, apocrineapical microvilli, apocrine

secretion ofsecretion of mucin/mucusmucin/mucus

Ciliated cellsCiliated cells -- numerous cilianumerous cilia

Short/basal cellsShort/basal cells -- undifferentiatedundifferentiated Brush cellsBrush cells -- apical microvilli (brush border):apical microvilli (brush border):

brush 1 cells- unusually longbrush 1 cells- unusually longmicrovilli;microvilli; brush 2 cells-brush 2 cells-

short microvillishort microvilli Small granule (APUD) cellsSmall granule (APUD) cells --

catecholamine-catecholamine- like secretionlike secretion

Free nerve endingsFree nerve endings

Mucous glands with serous demilunesMucous glands with serous demilunes


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TracheaTrachea


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TracheaTrachea Lamina propriaLamina propria areolarareolar

connective tissue, irregularconnective tissue, irregular

weave of collagen & elasticweave of collagen & elastic

fibers; many fibroblasts; alsofibers; many fibroblasts; also

lymphocytes, plasma cells,lymphocytes, plasma cells,macrophages, segmentersmacrophages, segmenters

Elastic membraneElastic membrane

between mucosa &between mucosa &

submucosasubmucosa

SubmucosaSubmucosa collagen,collagen,

fibroblasts, blood vessels,fibroblasts, blood vessels,

lymphaticslymphatics

CartilagesCartilages C-shapedC-shaped

hyaline cartilages; openhyaline cartilages; open


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BronchiBronchi


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BronchiolesBronchioles

BronchiolesBronchioles - simple columnar ciliated- simple columnar ciliatedepithelium;epithelium; bronchiolar (Clara) cells; brushbronchiolar (Clara) cells; brushcells; few smallcells; few small granule cells; smoothgranule cells; smooth

muscle cells; fibroblasts;muscle cells; fibroblasts; reticular, collagen &reticular, collagen &

elastic fibers; no cartilageelastic fibers; no cartilage

Terminal bronchiolesTerminal bronchioles - simple cuboidal non-- simple cuboidal non-ciliatedciliated epithelium;epithelium;

Respiratory bronchiolesRespiratory bronchioles - simple cuboidal- simple cuboidal

epitheliumepithelium with cilia; bronchiolar cells;with cilia; bronchiolar cells;smooth muscles;smooth muscles; fibroblasts; collagen fibersfibroblasts; collagen fibers

***NO cartilage in walls of bronchioles***NO cartilage in walls of bronchioles


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Bronchus & BronchioleBronchus & Bronchiole


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Alveolar Ducts, Atria, & SacsAlveolar Ducts, Atria, & Sacs

Respiratory bronchioleRespiratory bronchiole Alveolar ducts Alveolar ducts

Atria Alveolar sacsAtria Alveolar sacs AlveoliAlveoli Epithelium:Epithelium:

-- simple squamoussimple squamous (< 1m thick)(< 1m thick) type Itype Icellscells-- great alveolar/septal/ type II cellsgreat alveolar/septal/ type II cells

rounded or low cuboidal cells that protruderounded or low cuboidal cells that protrudeinto alveolar spaces; containinto alveolar spaces; contain multivesicular &multivesicular &multilamellar bodiesmultilamellar bodies (cytosomes); secrete(cytosomes); secretesurfactant (DPPC:surfactant (DPPC:DiPalmitoylPhosphatidylCholine); are alsoDiPalmitoylPhosphatidylCholine); are also

reserve cellsreserve cells can produce morecan produce more


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Alveolar Ducts, Sacs, AlveoliAlveolar Ducts, Sacs, Alveoli


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Alveolar CapillariesAlveolar Capillaries


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Alveolar CellsAlveolar Cells


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Pulmonary AlveolarPulmonary Alveolar

MacrophagesMacrophages


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The PleuraThe Pleura Visceral layerVisceral layer --

adherent to theadherent to theouter surface ofouter surface ofthe lungs;the lungs; simplesimple

squamoussquamousmesotheliummesothelium;;secretes pleuralsecretes pleuralfluidfluid

Parietal layerParietal layer --outer layer; linedouter layer; linedbyby mesotheliummesothelium;;separated fromseparated from

visceral layer byvisceral layer by


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The PleuraThe Pleura


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Thank You !Thank You !

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