Post on 02-Jun-2018
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RESPIRATORY SYSTEMRESPIRATORY SYSTEM
Histology lectureHistology lecture bbyy
Doc. MUDr.Doc. MUDr. DimitrolosDimitrolos KrajKraj,, CScCSc
Department of Histology & EmbryologyDepartment of Histology & Embryology
Faculty of Medicine,Faculty of Medicine, PalackPalackUniversity,University,
Olomouc, CZOlomouc, CZ
10/2009
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R E S P I R A T O R Y S Y S T E MR E S P I R A T O R Y S Y S T E M
It is composed ofIt is composed of2 principal regionsprincipal regions ::
11-- CONDUCTING PORTIONCONDUCTING PORTION
FunctionFunction:: Conducting, conditioningConducting, conditioning
((ccleansing, moistening, warming,)leansing, moistening, warming,)
and sampling (smelling) of airand sampling (smelling) of air
to breath.to breath.
22-- RESPIRATORY PORTIONRESPIRATORY PORTIONFunctionFunction:: Exchange ofExchange of
respiratory gases (Orespiratory gases (O22, CO, CO22))
from the air to blood.from the air to blood.[5]
LUNGS
NASAL,L
ARYNX,TRACHEA,BRO
NCHI
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THE WALLTHE WALLIN RESPIRATORY AIRWAYSIN RESPIRATORY AIRWAYS
A ]A ] Tunica MUCOSATunica MUCOSA-- composed ofcomposed of
a)a)Respiratory lining epitheliumRespiratory lining epithelium
pseudostratified columnarpseudostratified columnar
ciliated.ciliated.
bb)) Lamina propriaLamina propria --composed ofcomposed ofaa loose connective.loose connective.
B]B] TelaTela SUBMUCOSASUBMUCOSA composedcomposed
ofof cconnective tissue joiningonnective tissue joining
the mucosa, may be absent orthe mucosa, may be absent or
may be supported withmay be supported with ccartilageartilage
oror bbone.one.
C]C] Tunica ADVENTITIATunica ADVENTITIA
(May be absent in certain regions.)(May be absent in certain regions.)7Wall of a large bronchus, Tol.blue stain, LM x 250
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A ]A ] Tunica MUCOSATunica MUCOSA
It isIt is composedcomposed of :of :
a)a)Respiratory lining epitheliumRespiratory lining epithelium --
PSEUDOSTRATIFIED COLUMNARPSEUDOSTRATIFIED COLUMNAR
CILIATED EPCILIATED EPITHELIUMITHELIUM whichwhich
consists ofconsists of 6typestypesof cells :of cells :11 -- Columnar ciliated cellsColumnar ciliated cells --
Each cell possesses aboutEach cell possesses about 300 cilia300 cilia
on its apical surfaceon its apical surface ++basalbasal bodies.bodies.
((FFunctionunction: Transport of the mucus: Transport of the mucus
with entrapped dust partwith entrapped dust particlesicles..))
NumerousNumerous mitochondriamitochondriaare locatedare located
in the subsurface zone of thein the subsurface zone of the
apicalapical cytoplasm (sourcecytoplasm (source ofof ATP).ATP).11
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[7]
Apical part of ciliated respiratory
epithelial cells, EM x 9000
A ] Tunica MUCOSAA ] Tunica MUCOSA
[8]Pseudostrat. col. ciliated epithelium, H&E stain, LM x 540
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A ] Tunica MUCOSAA ] Tunica MUCOSA
[7]7Surface of ciliated epithelial cells, SEM x 2500Surface of ciliated epithelial cells, SEM x 2500Apical part of ciliated respiratory
epithelial cells, EM x 9000
MucociliaryMucociliary flowflow
http://localhost/var/www/apps/conversion/tmp/scratch_10/Movies/Cilia%20greyscale.flvhttp://localhost/var/www/apps/conversion/tmp/scratch_10/Movies/Cilia%20greyscale.flvhttp://localhost/var/www/apps/conversion/tmp/scratch_10/Movies/Cilia%20greyscale.flvhttp://localhost/var/www/apps/conversion/tmp/scratch_10/Movies/Cilia%20greyscale.flv8/10/2019 Lect Resp4d
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A ]A ] Tunica MUCOSATunica MUCOSA
(( 6 types of cells6 types of cells -- cont.)cont.)
22 -- Goblet cellsGoblet cells -- single cellsingle cell
mucous glands containingmucous glands containing
mucous droplets (polysaccharidemucous droplets (polysaccharide
rich products, PAS +).rich products, PAS +).33 -- Intermediate cellsIntermediate cells-- are growingare growing
cells transforming into ciliatedcells transforming into ciliated
or goblet cells.or goblet cells.
44 -- Basal cellsBasal cells-- are short cells restingare short cells resting
on basal lamina but not extendedon basal lamina but not extended
to the lumen they areto the lumen they are reregenerativegenerative
cells undergoing mitoses.cells undergoing mitoses.[11]
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A ]A ] Tunica MUCOSATunica MUCOSA
(( 6 types of cells6 types of cells -- cont.)cont.)
22 -- Goblet cellsGoblet cells -- single cellsingle cell
mucous glands containingmucous glands containing
mucous droplets (polysaccharidemucous droplets (polysaccharide
rich products, PAS +).rich products, PAS +).
33 -- Intermediate cellsIntermediate cells-- are growingare growing
cells transforming into ciliatedcells transforming into ciliated
or goblet cells.or goblet cells.
44 -- Basal cellsBasal cells-- are short cells restingare short cells resting
on basal lamina but not extendedon basal lamina but not extended
to the lumen they areto the lumen they are reregenerativegenerative
cells undergoing mitoses.cells undergoing mitoses.
[7]Goblet cells in respiratory ep.,
Tol.blue stain, LM x 350
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A ] Tunica MUCOSAA ] Tunica MUCOSA
(( 6 types of cells6 types of cells -- cont.)cont.)
55 -- Brush cellsBrush cells-- columnar cells withcolumnar cells with
numerous apicalnumerous apical microvillimicrovilliandand
afferent nerve endings on theirafferent nerve endings on their
basal surfacesbasal surfaces (sensory receptor(sensory receptor cells).cells).
66 -- Small granule cellsSmall granule cells-- similar tosimilar to
basal cells but with numerousbasal cells but with numerous
densedense--cored granulescored granules (diam.100(diam.100 --
200 nm) in their cytoplasm.200 nm) in their cytoplasm. They belong to the diffuseThey belong to the diffuse
neuroendocrineneuroendocrine systemsystem
(integration of the mucous and(integration of the mucous and
serous secretory processes).serous secretory processes). [11]
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A ]A ] Tunica MUCOSATunica MUCOSA
bb)) Lamina propriaLamina propria :: Is composed ofIs composed of aa loose connectiveloose connective
tissue with some elastic fibtissue with some elastic fibers,ers,
Mixed (seromucous)Mixed (seromucous) glandsglandsareare
frequently located here.frequently located here. Blood and lymphaticBlood and lymphatic vesselsvesselsandand
nerves are in the c. t.nerves are in the c. t.
Bundles ofBundles of smooth musclesmooth muscle maymay
be present in this layer.be present in this layer. Lymphoid nodulesLymphoid nodules ((MALTMALT== MMucosaucosa
AAssociatedssociated LLymphoidymphoid TTissue)issue)..
This layer may be continuous withThis layer may be continuous with
periosteum or perichondrium.periosteum or perichondrium.[8]Nasal cavity, intraepithelial gland, H&E, LM x 540
LP
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B]B] TelaTela SUBMUCOSASUBMUCOSA
It is composed of connectiveIt is composed of connectivetissue joining the mucosatissue joining the mucosa
with underlying structures.with underlying structures.
It may containIt may contain cartilagenouscartilagenous
segmentssegmentsandand smooth musclesmooth muscle(tunica fibro(tunica fibro--musculomusculo--cartilaginea).cartilaginea).
C] Tunica ADVENTITIA] Tunica ADVENTITIA(if present)(if present)
Is composed of a looseIs composed of a loose
connective tissue withconnective tissue with
blood vessels, peripheral nervesblood vessels, peripheral nerves
and lobules of adipose tissue.and lobules of adipose tissue.[8]Layers of the wall of trachea, H&E, LM x 200
LP
TS
TA
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NASAL CAVITYNASAL CAVITY
[A][A] VESTIBULEVESTIBULE
[B][B] NASAL FOSSAENASAL FOSSAE
Respiratory regionRespiratory regionOlfactory regionOlfactory region
[C][C] PARANASALPARANASAL
SINUSESSINUSES
[D][D] NASOPHARYNXNASOPHARYNX
[3]
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[A][A] VESTIBULEVESTIBULE of the nasal cavityof the nasal cavity
Lined byLined by stratified squamousstratified squamousepitheliumepithelium(thinly keratinized)(thinly keratinized)
Sebaceous glands and sweat glandsSebaceous glands and sweat glands
are in the lamina propria.are in the lamina propria.
Thick short hairsThick short hairs VIBRISSAEVIBRISSAE
are there to filter the air.are there to filter the air.
[11]
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[B][B] NASAL FOSSAENASAL FOSSAE
Composed ofComposed of: +: + Nasal CavitiesNasal Cavities++ Nasal SeptumNasal Septum
++ 3 Nasal Conchae3 Nasal Conchae-- sup., middle, inf.sup., middle, inf.
Two regions:Two regions:
1 Respiratory regionespiratory region :
Middle and inferior conchae areMiddle and inferior conchae are
covered by respir. lining epith.covered by respir. lining epith.
Lamina propria containsLamina propria contains
VENOUS PLEXUSESVENOUS PLEXUSES (swell bodies)(swell bodies)causing distention of conchalcausing distention of conchal
mucosa and decrease of airmucosa and decrease of air
flow velocity to warm up the airflow velocity to warm up the air
passing by.passing by.
x
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[B][B] NASAL FOSSAENASAL FOSSAE
Respiratoryespiratory
mucosaucosa :
Lamina propriaLamina propria
containscontains
VENOUS PLEXUSESVENOUS PLEXUSES(swell bodies)(swell bodies)
causing distentioncausing distention
of conchalof conchal
mucosa andmucosa anddecrease of airdecrease of air
flow velocity toflow velocity to
warm up the airwarm up the air
passing by.passing by. [11]
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Respiratory
and olfactory
mucosa,
Human, H&E,
LM x 270 [dk]OlfactoryOlfactorymucosamucosaOlfactoryOlfactorymucosamucosa
Respiratory mucosaRespiratory mucosaRespiratory mucosaRespiratory mucosa
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[B][B] NASAL FOSSAENASAL FOSSAE
2 Olfactory regionlfactory region:
Superior concha is coveredSuperior concha is covered
byby OLFACTORY EPITHELIUMOLFACTORY EPITHELIUM
which is awhich is a modifiedmodified
pseudostratified columnarpseudostratified columnar
(non(non--ciliated) epith.ciliated) epith. withoutwithout
goblet cells.goblet cells.
Lamina propria containsLamina propria contains
tuboalveolar (seromucous)tuboalveolar (seromucous)
BOWMANS GLANDSBOWMANS GLANDS andand
abundant blood vesselsabundant blood vessels
and nerves (fila olfactoria).and nerves (fila olfactoria).[3]
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[B][B] NASAL FOSSAENASAL FOSSAE
Olfactorylfactory
mucosa:ucosa:
OLFACTORYOLFACTORY
EPITHELIUMEPITHELIUMLamina propriaLamina propria
contains tuboalveolarcontains tuboalveolar
(seromucous)(seromucous)
BOWMANSBOWMANSGLANDSGLANDS andand
abundant bloodabundant blood
vessels and nervesvessels and nerves
(fila olfactoria).(fila olfactoria).[11]
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OLFACTORY EPITHELIUMOLFACTORY EPITHELIUM
It is composed of :It is composed of : Supporting cellsSupporting cells-- tall columnartall columnar
cells with microvilli.cells with microvilli.
Basal cellsBasal cells-- conical cells atconical cells at
the basal lamina.the basal lamina.
Olfactory cellsOlfactory cells-- bipolar neuronsbipolar neurons
with narrow apex and nonmotilewith narrow apex and nonmotile
cilia (9 +1 double microtubules).cilia (9 +1 double microtubules).
Afferent axons of these neuronsAfferent axons of these neurons
are directed toward CNSare directed toward CNS
(olfactory bulb).(olfactory bulb).
Fila olfactoriaFila olfactoria==unmyelinated ax.unmyelinated ax. [11]
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OLFACTORY EPITHELIUMOLFACTORY EPITHELIUM
BRAINBRAIN
[16]NASAL CAVITYNASAL CAVITY
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OLFACTORYOLFACTORY
EPITHELIUM (function)EPITHELIUM (function)
[1]
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[C][C] PARANASAL SINUSESPARANASAL SINUSES
FRONTAL, MAXILLARY, ETHMOID AND SPHENOID SINUSESFRONTAL, MAXILLARY, ETHMOID AND SPHENOID SINUSES are:are:
Lined with a thinner respiratory ciliated epithelium with a few goblet cells.Lined with a thinner respiratory ciliated epithelium with a few goblet cells.
Mucus drains into the nasal passages.Mucus drains into the nasal passages.
Lamina propria is continuous with periosteum of surrounding bones andLamina propria is continuous with periosteum of surrounding bones and
contains only a few glands.contains only a few glands.
[D][D] NASOPHARYNXASOPHARYNX
Is lined with respiratory typeIs lined with respiratory type
of epithelium.of epithelium.
There is aThere is a nasopharyngealnasopharyngeal
tonsiltonsil (adenoid) located(adenoid) located
in mucosa of the pharyngealin mucosa of the pharyngeal
fornix.fornix. x
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L A R Y N XL A R Y N X
It is a tube that connects the pharynx withIt is a tube that connects the pharynx with
the trachea, its functions are:the trachea, its functions are:
a) To createa) To create soundssoundsfor vocation.for vocation.
b) To prevent inspired airb) To prevent inspired air
enteringentering esophagus.esophagus.
c) To prevent ingested food andc) To prevent ingested food and
liquids entering theliquids entering the trachea.trachea.
It is composed of:It is composed of:
EPIGLOTTISEPIGLOTTIS andand
LARYNX PROPERLARYNX PROPER
5
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EPIGLOTTISEPIGLOTTIS
Has two surfaces:Has two surfaces:
11 -- Linqual surfaceLinqual surface -- coveredcoveredwithwith
stratified squamous noncornifiedstratified squamous noncornified
epithelium (oral).epithelium (oral).
22 -- Laryngeal surfaceLaryngeal surface -- coveredcoveredwithwith
pseudostratified columnar ciliatedpseudostratified columnar ciliated
epithelium (respiratory).epithelium (respiratory).
+ Supporting+ Supporting elasticelastic cartilage..cartilage..
+ Mixed glands.+ Mixed glands.
3
Larynx, vocal cords, laryngoscopic view
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EPIGLOTTISEPIGLOTTIS
1
Epiglottis, elastic cartilage, elastin stain, LM x 132Epiglottis, elastic cartilage, elastin stain, LM x 132
8
8 Detail of elastic cartilage, elastin stain, LM x 540Detail of elastic cartilage, elastin stain, LM x 540
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LARYNX PROPERLARYNX PROPER
Parts of the larynxParts of the larynx::
Vestibule.Vestibule.
False vocal cordsFalse vocal cords
(vestibular folds).(vestibular folds).
Laringeal ventricle.Laringeal ventricle. True vocal cordsTrue vocal cords
(vocal folds).(vocal folds).
StructureStructure::11-- MUCOSAMUCOSA:: Lined mostly withLined mostly with
pseudostratified columnar ciliatedpseudostratified columnar ciliated
epithelium with goblet cellsepithelium with goblet cells
(except for true vocal cords!).(except for true vocal cords!). 11
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LARYNX PROPERLARYNX PROPER
StructureStructure:: (cont.)(cont.)
22-- LAMINA PROPRIALAMINA PROPRIA:: containscontains
Loose connective tissue withLoose connective tissue with
Mixed glands andMixed glands and
Laryngeal cartilages:Laryngeal cartilages: thyroidthyroid,,cricoidcricoid,,arytenoidarytenoid
cartilcartil. are. are hyalinehyaline cartilages,cartilages,
epiglottis, cuneiform,epiglottis, cuneiform,
corniculatecorniculateandand tips oftips of
arytenoidarytenoidareare elasticelastic cartilagescartilages
Binding ligamentsBinding ligaments
Intrinsic muscles of the larynx.Intrinsic muscles of the larynx.(striated muscle)(striated muscle)
11
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LARYNX PROPERLARYNX PROPER
StructureStructure:: (cont.)(cont.)
FALSE VOCAL CORDS :FALSE VOCAL CORDS :
(vestibular folds)(vestibular folds)
Are covered by respiratory liningAre covered by respiratory lining
epithelium (pseudostratifiedepithelium (pseudostratifiedcolumnar ciliated).columnar ciliated).
SeroSero--mucous glands in the laminamucous glands in the lamina
propria.propria.
Fibrocollagenous stroma withFibrocollagenous stroma withlymphatic nodules.lymphatic nodules.
Ventricular recessVentricular recess invaginatesinvaginates
between the false and true vocalbetween the false and true vocal
folds.folds.11
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LARYNX PROPERLARYNX PROPER
StructureStructure:: (cont.)(cont.)
TRUE VOCAL CORDS :TRUE VOCAL CORDS :
Are covered by stratifiedAre covered by stratified
squamoussquamous uncornifieduncornified epithelium.epithelium.
Bundles of elastic fibers in laminaBundles of elastic fibers in laminapropriapropria ( VOCAL LIGAMENT ).( VOCAL LIGAMENT ).
Skeletal muscleSkeletal muscle ( VOCALIS( VOCALIS
MUSCLE ).MUSCLE ).
10Larynx, frontal section, LM x 10
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LARYNX PROPERLARYNX PROPER
Human larynx, frontal section, H&E, LM x 14 8Vocal cords in actionVocal cords in action
http://localhost/var/www/apps/conversion/tmp/scratch_10/Movies/Laryngoscopy%20-%20Vocal%20Cords%20in%20Action.flvhttp://localhost/var/www/apps/conversion/tmp/scratch_10/Movies/Laryngoscopy%20-%20Vocal%20Cords%20in%20Action.flvhttp://localhost/var/www/apps/conversion/tmp/scratch_10/Movies/Laryngoscopy%20-%20Vocal%20Cords%20in%20Action.flv8/10/2019 Lect Resp4d
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T R A C H E AT R A C H E A
Is a thinIs a thin--walled rigid tubewalled rigid tube
(10 cm long x 2.3 cm in diam.)(10 cm long x 2.3 cm in diam.)
extending from the base of larynxextending from the base of larynx
to the bifurcation into twoto the bifurcation into two
primary bronchi.primary bronchi.
Its wall is has the following layers:Its wall is has the following layers:
A] T. MUCOSAA] T. MUCOSA
B] T. SUBMUCOSAB] T. SUBMUCOSA
C] T. ADVENTITIAC] T. ADVENTITIA
11
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T R A C H E AT R A C H E A
A]A] T. MUCOSAT. MUCOSA:: consisting ofconsisting of
Respiratory liningRespiratory lining PSEUDOSTRATIFIEDPSEUDOSTRATIFIED
COLUMNAR CILIATEDCOLUMNAR CILIATEDEPITHELIUMEPITHELIUM
with tall columnar ciliated cells,with tall columnar ciliated cells,
basal cells and some goblet cells.basal cells and some goblet cells. L.P.L.P. is a loose connective tissueis a loose connective tissue
with serowith sero--mucous glandsmucous glands
((tracheal glandstracheal glands). These are more). These are more
numerous within the posteriornumerous within the posteriorwall of the tracheawall of the trachea (membranous part).(membranous part).
Some lymphoid nodules.Some lymphoid nodules.
Blood vesselsBlood vessels (mainly capillaries).(mainly capillaries).11
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T R A C H E AT R A C H E A
A]A] T. MUCOSAT. MUCOSA:: consisting ofconsisting of
Respiratory liningRespiratory lining PSEUDOSTRATIFIEDPSEUDOSTRATIFIED
COLUMNAR CILIATEDCOLUMNAR CILIATEDEPITHELIUMEPITHELIUM
with tall columnar ciliated cells,with tall columnar ciliated cells,
basal cells and some goblet cells.basal cells and some goblet cells. L.P.L.P. is a loose connective tissueis a loose connective tissue
with serowith sero--mucous glandsmucous glands
((tracheal glandstracheal glands). These are more). These are more
numerous within the posteriornumerous within the posteriorwall of the tracheawall of the trachea (membranous part).(membranous part).
Some lymphoid nodules.Some lymphoid nodules.
Blood vesselsBlood vessels (mainly capillaries).(mainly capillaries).8Trachea, l.s., H&E, LM x 270
E
SMG
LP
HC
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T R A C H E AT R A C H E A
B]B] T. SUBMUCOSAT. SUBMUCOSA::
the fibrothe fibro--musculomusculo--cartilaginouscartilaginous
layer containslayer contains
CC--shaped (incomplete) ringsshaped (incomplete) rings
(16(16--20 pcs) of the20 pcs) of the hyaline cartilagehyaline cartilage
surrounded by a connective tissue,surrounded by a connective tissue,
openings of the rings are orientedopenings of the rings are oriented
to the posterior surface of theto the posterior surface of the
trachea and transversed withtrachea and transversed with
fibroelastic ligamentfibroelastic ligamentandand
Smooth muscle bundlesSmooth muscle bundles
(TRACHEALIS MUSCLE).(TRACHEALIS MUSCLE). 11
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T R A C H E AT R A C H E A
C]C] T. ADVENTITIAT. ADVENTITIA::
Is composed of a looseIs composed of a loose
connective tissue withconnective tissue with
blood vesselsblood vessels..
Branches of peripheralBranches of peripheralnervesnerves and lobules ofand lobules of
adipose tissueadipose tissue..
It fixes the trachea to theIt fixes the trachea to the
surrounding connectivesurrounding connective
tissue oftissue of mediastinummediastinum..
11Childs trachea, overview, t.s., LM x 25Childs trachea, overview, t.s., LM x 25
Trachea LMTrachea LM
EE
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Trachea LMTrachea LM
8Layers of the wall of trachea, H&E, LM x 200
EE
LPLP
CC
AA
TRACHEOTOMYTRACHEOTOMY
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BRONCHIAL TREEBRONCHIAL TREE
The bronchial tree can be divided into:The bronchial tree can be divided into:
[A][A] EXTRAPULMONARYEXTRAPULMONARYBRONCHIBRONCHI-- Direct continuation of trachea beyondDirect continuation of trachea beyond
itsits bifucrationbifucration..
-- Located in theLocated in the mediastinummediastinum outsideoutside
lungs.lungs.
[B][B] INTRAPULMONARY BRONCHIINTRAPULMONARY BRONCHI-- Located inside lungs.Located inside lungs.
-- Always surrounded with alveoli andAlways surrounded with alveoli and
the other structures of the lung.the other structures of the lung.
[C] BRONCHIOLES[C] BRONCHIOLES
[D] TERMINAL BRONCHIOLES[D] TERMINAL BRONCHIOLES
[E] RESPIRATORY BRONCHIOLES[E] RESPIRATORY BRONCHIOLES 5
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BRONCHIAL TREEBRONCHIAL TREE
10
The bronchial tree can be divided into:The bronchial tree can be divided into:
[A][A] EXTRAPULMONARYEXTRAPULMONARYBRONCHIBRONCHI-- Direct continuation of trachea beyondDirect continuation of trachea beyond
itsits bifucrationbifucration..
-- Located in theLocated in the mediastinummediastinum outsideoutside
lungs.lungs.
[B][B] INTRAPULMONARY BRONCHIINTRAPULMONARY BRONCHI-- Located inside lungs.Located inside lungs.
-- Always surrounded with alveoli andAlways surrounded with alveoli and
the other structures of the lung.the other structures of the lung.
[C] BRONCHIOLES[C] BRONCHIOLES
[D] TERMINAL BRONCHIOLES[D] TERMINAL BRONCHIOLES
[E] RESPIRATORY BRONCHIOLES[E] RESPIRATORY BRONCHIOLES
O C SO C S
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[A][A] --PRIMARY BRONCHUSPRIMARY BRONCHUS
The structure is similar to trachea exceptThe structure is similar to trachea except
for the cartilage and smooth muscle !!for the cartilage and smooth muscle !!
The lamina propria is moreThe lamina propria is moredensedensewithwith
higher proportion of elastic fibers.higher proportion of elastic fibers.
SeroSero--mucousmucous glandsglandsand lymphocytesand lymphocytesare well developed.are well developed.
TheThe cartilagecartilage (hyaline) is irregular in(hyaline) is irregular in
shape and formsshape and forms incomplete rings orincomplete rings or
segments.segments. The smooth muscle layer in the laminaThe smooth muscle layer in the lamina
propria is ofpropria is of spiralspiralarrangement andarrangement and
progressively more prominent.progressively more prominent.17
Primary bronchus, van Gieson/Alcian blue, LM x 150
[B][B] INTRAPULMONARY BRONCHIINTRAPULMONARY BRONCHI[B][B] INTRAPULMONARY BRONCHIINTRAPULMONARY BRONCHI
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[B][B] -- INTRAPULMONARY BRONCHIINTRAPULMONARY BRONCHI[B][B] -- INTRAPULMONARY BRONCHIINTRAPULMONARY BRONCHI
Located inside lungsLocated inside lungs -- secondary,secondary,
tertiary etc., (diam.tertiary etc., (diam.>1 mm>1 mm).).
Their structure is similar to the primaryTheir structure is similar to the primary
bronchus but it has :bronchus but it has :
Less goblet cellsLess goblet cells in the respiratoryin the respiratoryepithelium.epithelium.
The cartilage is moreThe cartilage is more fragmentedfragmented
(incomplete profiles).(incomplete profiles).
Only a fewOnly a few serosero--mucous glands inmucous glands inlamina propria.lamina propria.
Bundles ofBundles of smooth musclesmooth muscle areare
more prominent.more prominent.
Located inside lungsLocated inside lungs -- secondary,secondary,
tertiary etc., (diam.tertiary etc., (diam.>1 mm>1 mm).).
Their structure is similar to the primaryTheir structure is similar to the primary
bronchus but it has :bronchus but it has :
Less goblet cellsLess goblet cells in the respiratoryin the respiratoryepithelium.epithelium.
The cartilage is moreThe cartilage is more fragmentedfragmented
(incomplete profiles).(incomplete profiles).
Only a fewOnly a few serosero--mucous glands inmucous glands inlamina propria.lamina propria.
Bundles ofBundles of smooth musclesmooth muscle areare
more prominent.more prominent.7
[B][B] INTRAPULMONARY BRONCHIINTRAPULMONARY BRONCHI[B][B] INTRAPULMONARY BRONCHIINTRAPULMONARY BRONCHI
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Small bronchus, H&E stain, LM x 75
[B][B] -- INTRAPULMONARY BRONCHIINTRAPULMONARY BRONCHI[B][B] -- INTRAPULMONARY BRONCHIINTRAPULMONARY BRONCHI
Located inside lungsLocated inside lungs -- secondary,secondary,
tertiary etc., (diam.tertiary etc., (diam.>1 mm>1 mm).).
Their structure is similar to the primaryTheir structure is similar to the primary
bronchus but it has :bronchus but it has :
Less goblet cellsLess goblet cells in the respiratoryin the respiratoryepithelium.epithelium.
The cartilage is moreThe cartilage is more fragmentedfragmented
(incomplete profiles).(incomplete profiles).
Only a fewOnly a few serosero--mucous glands inmucous glands inlamina propria.lamina propria.
Bundles ofBundles of smooth musclesmooth muscle areare
more prominent.more prominent.6
[B][B] INTRAPULMONARY BRONCHIINTRAPULMONARY BRONCHI[B][B] INTRAPULMONARY BRONCHIINTRAPULMONARY BRONCHI
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[B][B] -- INTRAPULMONARY BRONCHIINTRAPULMONARY BRONCHI[B][B] -- INTRAPULMONARY BRONCHIINTRAPULMONARY BRONCHI
(Cont.)(Cont.)
Numerous lymphocytes andNumerous lymphocytes and
lymphoid noduleslymphoid nodules ((BALTBALT))areare
located in the lamina propria withlocated in the lamina propria with
diapedesis of lymphocytesdiapedesis of lymphocytesthrough the epithelium.through the epithelium.
Each intrapulmonary bronchus isEach intrapulmonary bronchus is
accompanied by branches of theaccompanied by branches of the
pulmonary artery and veinpulmonary artery and vein+ lymphatic vessels,+ lymphatic vessels,
+ smaller bronchial artery.+ smaller bronchial artery.
7
Wall of a bronchus with lymphoid tissue LM x 250
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Intrapulmonary bronchusIntrapulmonary bronchus
[8]
Intrapulmonary bronchus, t. s., H&E, LM x 132
EE
SMSM
CC CC
[C][C] BRONCHIOLESBRONCHIOLES[C][C] BRONCHIOLESBRONCHIOLES
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[C][C] -- BRONCHIOLESBRONCHIOLES[C][C] -- BRONCHIOLESBRONCHIOLES
(( diameterdiameter< 1 mm< 1 mm))
TheyThey hahaveve the epithelium stillthe epithelium still
pseudostratified columnar ciliatedpseudostratified columnar ciliated
butbut ::
It is lower and withIt is lower and with very few gobletvery few goblet
cells.cells.
No glandsNo glands mucosal glands are inmucosal glands are in
lamina propria.lamina propria.
No cartilageNo cartilage is present in the wall.is present in the wall.
It has well developed continuousIt has well developed continuous
layer of spirallayer of spiral smooth musclesmooth muscle cellscells
and elastic fibers.and elastic fibers.
8Bronchiol, t.s., H&E, LM x 270
Lumen
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Bronchiol,LMBronchiol,LM
17
Bronchiol, t.s., H&E, LM x 160
[D][D] TERMINAL BRONCHIOLESTERMINAL BRONCHIOLES
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[D][D] -- TERMINAL BRONCHIOLESTERMINAL BRONCHIOLES
(( diam.diam. 0.30.3 -- 0.1 mm0.1 mm ))
It has :It has :
EpitheliumEpithelium simplesimplecolumnarcolumnar
ciliated (withciliated (withnono goblet cellsgoblet cells
butbutClara cellsClara cellsinsteadinstead).).
NoNo glands andglands and nono cartilage incartilage in
lamina propria.lamina propria.
Elastic fibresElastic fibres
areare in lamina proprin lamina propriaia..
Thin layer ofThin layer of smooth musclesmooth muscle
hashas spiral arrangement.spiral arrangement.
8
[D][D] TERMINAL BRONCHIOLESTERMINAL BRONCHIOLES
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[D][D] -- TERMINAL BRONCHIOLESTERMINAL BRONCHIOLES
(( diam.diam. 0.30.3 -- 0.1 mm0.1 mm ))
It has :It has :
EpitheliumEpithelium simplesimplecolumnarcolumnar
ciliated (withciliated (withnono goblet cellsgoblet cells
butbutClara cellsClara cellsinsteadinstead).).
NoNo glands andglands and nono cartilage incartilage in
lamina propria.lamina propria.
Elastic fibresElastic fibres
areare in lamina proprin lamina propriaia..
Thin layer ofThin layer of smooth musclesmooth muscle
hashas spiral arrangement.spiral arrangement.
8Lung, terminal bronchioles, H&E, LM x 132
[D][D] TERMINAL BRONCHIOLESTERMINAL BRONCHIOLES
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[D][D] -- TERMINAL BRONCHIOLESTERMINAL BRONCHIOLES
CLARA CELLSCLARA CELLSin the epithelium are:in the epithelium are:
NonNon--ciliatedciliatedcolumnar cells withcolumnar cells withindented nuclei.indented nuclei.
Contain membraneContain membrane--boundboundgranulesgranules(0.3 um in diam.)(0.3 um in diam.)
in their bulbous apical cytoplasm.in their bulbous apical cytoplasm.
They are secretory cells to produceThey are secretory cells to produce
glycosaminoglycansglycosaminoglycans andandcholesterol as a protective layer.cholesterol as a protective layer.
10
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Clara cellsClara cells
[7]Clara cells in the epithelium of a terminal bronchiole, Tol. blue stain, LM x 350
[E][E] RESPIRATORY BRONCHIOLESRESPIRATORY BRONCHIOLES
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Terminal
bronchioleElasticfibers
[E][E] -- RESPIRATORY BRONCHIOLESRESPIRATORY BRONCHIOLES
They make a transition between conductingThey make a transition between conducting
and respiratory portions of the lung.and respiratory portions of the lung.Their structure is identical to the terminalTheir structure is identical to the terminal
bronchioles but they:bronchioles but they:
Are linedAre lined onlyonly byby nonnon--ciliatedciliatedsimplesimple
cuboidal epithelium withcuboidal epithelium withClara cellsClara cells.. Have numerousHave numerous saccularsaccular alveolialveoli
attached to their wallsattached to their walls (as the first(as the firstspots of gas exchange)spots of gas exchange)which arewhich are
lined by simple squamous alveolarlined by simple squamous alveolarepithelium.epithelium.
TThey have some smooth musclehey have some smooth muscle
cells and elastic fibcells and elastic fibeersrs in the wall.in the wall.1
[E][E] RESPIRATORY BRONCHIOLESRESPIRATORY BRONCHIOLES
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[E][E] -- RESPIRATORY BRONCHIOLESRESPIRATORY BRONCHIOLES
They make a transition between conductingThey make a transition between conducting
and respiratory portions of the lung.and respiratory portions of the lung.Their structure is identical to the terminalTheir structure is identical to the terminal
bronchioles but they:bronchioles but they:
Are linedAre lined onlyonly byby nonnon--ciliatedciliatedsimplesimple
cuboidal epithelium withcuboidal epithelium withClara cellsClara cells.. Have numerousHave numerous saccularsaccular alveolialveoli
attached to their wallsattached to their walls (as the first(as the firstspots of gas exchange)spots of gas exchange)which arewhich are
lined by simple squamous alveolarlined by simple squamous alveolarepithelium.epithelium.
TThey have some smooth musclehey have some smooth muscle
cells and elastic fibcells and elastic fibeersrs in the wall.in the wall.8
Respiratory bronchiole, H&E, LM x 270
RBRB
[F][F] ALVEOLAR DUCTSALVEOLAR DUCTS
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[F][F] -- ALVEOLAR DUCTSALVEOLAR DUCTS
They are tiny tubular spacesThey are tiny tubular spaces
completely surrounded bycompletely surrounded byalveolialveoli..
TheyThey
Are lined with simple squamousAre lined with simple squamous
alveolar cells (alveolar cells ( type 1type 1).). Contain thin bundles of smoothContain thin bundles of smooth
muscle cells encircling the duct asmuscle cells encircling the duct as
well as its opening into alveoliwell as its opening into alveoli
((sphinctersphincter--like bundleslike bundles).). Are supported also by bundles ofAre supported also by bundles of
reticular and elastic fibers in theirreticular and elastic fibers in their
thin wall.thin wall.8
[G][G] ALVEOLIALVEOLI
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[G][G] -- ALVEOLIALVEOLI
ATRIAATRIA -- are initial portions ofare initial portions of
ALVEOLAR SACSALVEOLAR SACS(groups of alveoli).(groups of alveoli).
ALVEOLIALVEOLI -- are the terminal portionsare the terminal portions
of the bronchial tree directlyof the bronchial tree directly
responsible for Oresponsible for O22and COand CO22exchange.exchange.
they are sackthey are sack--like evaginationslike evaginations
(200(200 m in diam.) lined bym in diam.) lined by
veryvery thinthin simple squamoussimple squamous
epitheliumepitheliumcomposed ofcomposed of
2 kinds2 kindsof cells:of cells: Type I cellsType I cells
Type II cellsType II cells
8x 270
Alveolarduct
Alveolarsac
Alveolus
Alveolus
Alveolus
Alveolus
Alveolus
x 270
[G][G] ALVEOLIALVEOLI
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[G][G] -- ALVEOLIALVEOLI
1.1. Type I cellsType I cells ::((PneumocytePneumocyte I)I)
(SQUAMOUS ALVEOLAR CELLS,(SQUAMOUS ALVEOLAR CELLS,97 %97 %))TheyThey
are veryare veryflatflatcells with continuouscells with continuousplasma membraneplasma membrane
have organelles (GER, GA, M)have organelles (GER, GA, M)
located mainly around thelocated mainly around the
nucleusnucleus
have abundanthave abundant pinocytoticpinocytotic
vesicles located in the thin areasvesicles located in the thin areas
of the cytoplasmof the cytoplasm havehave desmosomesdesmosomesandand
occluding junctionsoccluding junctions to jointo join
the cells tightly togetherthe cells tightly together
7
Alveolus
Alveolus
Alveolus
[G][G] ALVEOLIALVEOLI
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Alveolus
Alveolus
[G][G] -- ALVEOLIALVEOLI
22.. Type II cells :Type II cells : ((PneumocytePneumocyte II)II)
(GREAT ALVEOLAR CELLS(GREAT ALVEOLAR CELLSor SEPTAL CELLS,or SEPTAL CELLS, 3 %3 %))
TheyThey
Are interspersed among theAre interspersed among the
type I cells.type I cells.
Are cuboidal or polygonal in shape,Are cuboidal or polygonal in shape,
found solitary or in groups infound solitary or in groups in
corners of alveoli.corners of alveoli.
AreAresecretory cellssecretory cellscontainingcontaining
several organelles (M, GER,several organelles (M, GER,
well developed GA), andwell developed GA), and
numerousnumerous microvillimicrovilli areare
on their apical surfaces.on their apical surfaces. 7
[G][G] ALVEOLIALVEOLI
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[G][G] -- ALVEOLIALVEOLI
22.. Type II cells:Type II cells:((PneumocytePneumocyte II)II)
(Cont.)(Cont.)
Have special membraneHave special membrane--limitedlimitedlamellar bodieslamellar bodies,, observedobserved
in their cytoplasm under EMin their cytoplasm under EM
(diam.1(diam.1--22 m), containingm), containing
phospholipids and proteins.phospholipids and proteins.
TheyThey produceproduce pulmonarypulmonary
surfactantsurfactant (which contains(which contains
dipalmitoyldipalmitoyl lecithin) to lowerlecithin) to lower
alveolar surface tension andalveolar surface tension and
to prevent alveoli fromto prevent alveoli from
collapsing during expiration.collapsing during expiration.
It also has bactericidal effect .It also has bactericidal effect .7
Alveolus
EM x 270
Alveolus
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Type II cellType II cell
7
INTERINTER--ALVEOLAR SEPTUMALVEOLAR SEPTUM
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INTERINTER--ALVEOLAR SEPTUMALVEOLAR SEPTUM
Is a very thin wall between twoIs a very thin wall between two
neighboring alveoli which consists of:neighboring alveoli which consists of:
11 -- Thin squamousThin squamous epithelial cellsepithelial cells((pneumocytespneumocytes I) on both sides.I) on both sides.
22 -- Blood capillariesBlood capillariessandwiched insandwiched inbetween the two layers of cells.between the two layers of cells.
33 -- InterstitiumInterstitiumwith reticular andwith reticular and
elastic fibers and some fibroblasts,elastic fibers and some fibroblasts,
mast cells and macrophagesmast cells and macrophages
(interstitial dust cells).(interstitial dust cells).
8
Alveolus
Alveolus
Alveolus
Lung, interalveolar septum, H&E, LM x 540
STRUCTURE OF THE BLOODSTRUCTURE OF THE BLOOD AIR BARRIERAIR BARRIER
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STRUCTURE OF THE BLOODSTRUCTURE OF THE BLOOD--AIR BARRIERAIR BARRIER
It is composed ofIt is composed of33componentscomponents11-- Cytoplasm of theCytoplasm of the flat alveolarflat alveolar
cellscells (type I.)(type I.)
22-- Fused basal laminaFused basal lamina ofof
apposed alveolar andapposed alveolar andendothelial cells.endothelial cells.
33-- Cytoplasm of the flatCytoplasm of the flat
endothelial cellsendothelial cells (which is(which is
the continuous type ofthe continuous type ofcapillary).capillary).
NoteNote :: 300 million alveoli in lungs300 million alveoli in lungs
= 140 m= 140 m22of exchange surface area.of exchange surface area.10
AIR
AIR
BLOOD
STRUCTURE OF THE BLOODSTRUCTURE OF THE BLOOD AIR BARRIERAIR BARRIER
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STRUCTURE OF THE BLOODSTRUCTURE OF THE BLOOD--AIR BARRIERAIR BARRIER
It is composed ofIt is composed of33componentscomponents11-- Cytoplasm of theCytoplasm of the flat alveolarflat alveolar
cellscells (type I.)(type I.)
22-- Fused basal laminaFused basal lamina ofof
apposed alveolar andapposed alveolar andendothelial cells.endothelial cells.
33-- Cytoplasm of the flatCytoplasm of the flat
endothelial cellsendothelial cells (which is(which is
the continuous type ofthe continuous type ofcapillary).capillary).
NoteNote :: 300 million alveoli in lungs300 million alveoli in lungs
= 140 m= 140 m22of exchange surface area.of exchange surface area.10Electron micrograph of lung alveoli, EM x 5800
AIR
AIR
BLOOD
STRUCTURE OF THE BLOODSTRUCTURE OF THE BLOOD AIR BARRIERAIR BARRIER
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STRUCTURE OF THE BLOODSTRUCTURE OF THE BLOOD--AIR BARRIERAIR BARRIER
10
AIR
AIR
BLOOD
Electron micrograph of lung alveoli, EM x 5800
It is composed ofIt is composed of33componentscomponents11-- Cytoplasm of theCytoplasm of the flat alveolarflat alveolar
cellscells (type I.)(type I.)
22-- Fused basal laminaFused basal lamina ofof
apposed alveolar andapposed alveolar andendothelial cells.endothelial cells.
33-- Cytoplasm of the flatCytoplasm of the flat
endothelial cellsendothelial cells (which is(which is
the continuous type ofthe continuous type ofcapillary).capillary).
NoteNote :: 300 million alveoli in lungs300 million alveoli in lungs
= 140 m= 140 m22of exchange surface area.of exchange surface area.
STRUCTURE OF THE BLOODSTRUCTURE OF THE BLOOD--AIR BARRIERAIR BARRIER
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STRUCTURE OF THE BLOODSTRUCTURE OF THE BLOOD--AIR BARRIERAIR BARRIER
11
AIR
AIR
BLOOD
7
DUST CELLSDUST CELLS
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DUST CELLSDUST CELLS
TheyThey
Are cells derived fromAre cells derived from monocytesmonocytes..
Are found in the interior ofAre found in the interior of alveolaralveolarseptumseptum (interstitial(interstitial localilocalizzationation))
as well as on theas well as on the alveolar surfacealveolar surface
((intralveolarintralveolar localilocalizzationation, alveolar, alveolarmacrophages).macrophages).
Accumulate dust and otherAccumulate dust and othermicroparticlesmicroparticles and store themand store them
mainly within themainly within the perivascularperivascular
spaces and in the pleura.spaces and in the pleura.
SomeSome intralveolarintralveolar macrophages maymacrophages may
be expectorated or swallowed later.be expectorated or swallowed later.8
Lung, dust cells, H&E, LM x 270
DUST CELLSDUST CELLS
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DUST CELLSDUST CELLS
[8]
AIR
AIR
AIR
BLOOD
[8]
AIR
AIR
AIR
AIR
Lung, dust cells, H&E, LM x 540Lung, dust cells, H&E, LM x 540
ALVEOLAR PORESALVEOLAR PORES
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ALVEOLAR PORESALVEOLAR PORES
Pores of KohnPores of Kohn aarere
1010 -- 1515 m pores within them pores within theinteralveolarinteralveolar septum connectingseptum connecting
the neighboring alveoli.the neighboring alveoli.
They equalize pressure in theThey equalize pressure in the
alveoli and allow for collateralalveoli and allow for collateral
circulation (when necessary).circulation (when necessary).
11
L
2Lung, EM x 7000Lung, EM x 7000
[H][H] -- PLEURAPLEURA
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[H][H] PLEURAPLEURA
It is the serous membraneIt is the serous membrane
covering lungs withcovering lungs with 22 layers:layers:
1. parietal pleura1. parietal pleura
2. visceral pleura2. visceral pleura
Both layers are composed ofBoth layers are composed of
one layer ofone layer of MESOTHELIALMESOTHELIAL
CELLSCELLS(simple squamous(simple squamous epep.)..).
They are supported by fineThey are supported by fineconnective tissue layerconnective tissue layer
(with some elastic fibers).(with some elastic fibers).
7
[I][I] -- PULMONARY BLOOD VESSELSPULMONARY BLOOD VESSELS
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[I][I] PULMONARY BLOOD VESSELSPULMONARY BLOOD VESSELS
They are of two kinds:They are of two kinds:
1)1) Nutrient circulationNutrient circulation::(systemic)(systemic) These blood vessels follow theThese blood vessels follow the
bronchial tree up to the respiratorybronchial tree up to the respiratory
bronchioles and then they anastomosebronchioles and then they anastomose
with the functional circulation.with the functional circulation.
2)2) Functional circulationFunctional circulation::(pulmonary)(pulmonary)
Pulmonary arteries are thin walledPulmonary arteries are thin walled
with more smooth muscle and elasticwith more smooth muscle and elastic
fibers andfibers and prominent internalprominent internal
elastic membraneelastic membrane..
They branch alongside the bronchialThey branch alongside the bronchial
tree and their adventitia fusestree and their adventitia fuses
with the same layer of bronchi.with the same layer of bronchi.
Veins follow the same route.Veins follow the same route.
3
L
Bronchial artery, elast. stain, LM x 250Bronchial artery, elast. stain, LM x 250
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Histologic features in the course of theHistologic features in the course of the
bronchial treebronchial tree
10
DEVELOPMENT OF THE RESPIRATORY SYSTEMDEVELOPMENT OF THE RESPIRATORY SYSTEM
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CONTENTSONTENTS
ORIGIN OF THE RESPIRATORY PRIMORDIUMORIGIN OF THE RESPIRATORY PRIMORDIUM (RESP. DIVERTICULUM)(RESP. DIVERTICULUM)
DEVELOPMENT OF THE LARYNXDEVELOPMENT OF THE LARYNX
DEVELOPMENT OF EXTRAPULMONARY BRONCHIDEVELOPMENT OF EXTRAPULMONARY BRONCHI
DEVELOPMENT OF INTRAPULMONARY BRONCHIAL TREEDEVELOPMENT OF INTRAPULMONARY BRONCHIAL TREE
DEVELOPMENT OF LUNG ALVEOLIDEVELOPMENT OF LUNG ALVEOLI
SEPARATION OF THE THORACAL CAVITYSEPARATION OF THE THORACAL CAVITY
DEVELOPMENT OF THE RESPIRATORY SYSTEMDEVELOPMENT OF THE RESPIRATORY SYSTEM
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TheThe primordiumprimordium of the lowerof the lower
respiratory system developsrespiratory system developsas an outgrowth from theas an outgrowth from the
ventral wall of the foregutventral wall of the foregut
calledcalled respiratoryrespiratory
diverticulumdiverticulum.. TheThe epitheliumepithelium of the resp.of the resp.
diverticulumdiverticulum is ofis of
endodermalendodermal originorigin..
TheThe cartilaginouscartilaginousandandmuscularmuscularcomponents arecomponents are
derived from thederived from the
surroundingsurrounding splanchnicsplanchnic
mesodermmesoderm..x
DEVELOPMENT OF THE RESPIRATORY SYSTEMDEVELOPMENT OF THE RESPIRATORY SYSTEM
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Initially the respiratoryInitially the respiratory diverticulumdiverticulum communicatescommunicates widely with the foregut,widely with the foregut,
but later thebut later the esophagotrachealesophagotracheal ridgesridgesappear and theappear and the esophagotrachealesophagotrachealseptumseptumdevelops to separate the respiratory and digestive canals.develops to separate the respiratory and digestive canals.
x
4 weeks 5 weeks
DEVELOPMENT OF THE LARYNXDEVELOPMENT OF THE LARYNX
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DEVELOPMENT OF THE LARYNXDEVELOPMENT OF THE LARYNX
TheThe internal lininginternal lining develops from thedevelops from theendodermendoderm of the upper portion ofof the upper portion of
the respiratorythe respiratory diverticulumdiverticulum ((laryngolaryngo--tracheal tube).tracheal tube). TheThe laryngeal orificelaryngeal orificechanges from achanges from a sagittalsagittal slitslit to ato a TT--shapedshaped
opening due to the development of pairedopening due to the development of paired arytenoidarytenoid swellingsswellings..
The epiglottis develops from theThe epiglottis develops from theepiglottal swellingepiglottal swellinglocated ventrally tolocated ventrally to
the orifice.the orifice. TheThe laryngeal epithelium proliferateslaryngeal epithelium proliferates rapidly andrapidly andtemporary closestemporary closes
lumen of the developing larynx.lumen of the developing larynx.
x
4 weeks 5 weeks
DEVELOPMENT OF THE LARYNXDEVELOPMENT OF THE LARYNX
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DEVELOPMENT OF THE LARYNXDEVELOPMENT OF THE LARYNX
RecanalizationRecanalizationoccurs by theoccurs by the 1010ththweekweekand theand the laryngeal ventricleslaryngeal ventricles formform
subsequently.subsequently. The folds of tissue on both sides of the recess differentiate into theThe folds of tissue on both sides of the recess differentiate into the falsefalseandand
true vocal cordstrue vocal cords..
TheThe laryngeal cartilageslaryngeal cartilages( thyroid,( thyroid, cricoidcricoid and arytenoids) develop from theand arytenoids) develop from the
mesenchymemesenchyme of the last twoof the last two branchialbranchial arches (arches (44thth
+ 6+ 6thth
).). TheThe laryngeal muscleslaryngeal musclesdevelop fromdevelop from myoblastsmyoblasts in the 4th and 6thin the 4th and 6th
branchialbranchial arches.arches.
x
6 weeks 10 weeks
DEVELOPMENT OF THE TRACHEADEVELOPMENT OF THE TRACHEA
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TheThetracheatrachea developsdevelopsfrom thefrom the distaldistalportion of theportion of the laryngotracheallaryngotracheal tubetube..
ItsIts endodermendodermgives rise to thegives rise to theepitheliumepithelium andandglands.glands.
TheTheconnective tissue, cartilage and musclesconnective tissue, cartilage and muscles of the trachea develop fromof the trachea develop from
the surroundingthe surrounding splanchnicsplanchnic mesenchymemesenchyme..
TheThe distal enddistal endof theof the laryngotracheallaryngotracheal tube swells and forms thetube swells and forms the lung budlung budwhich divides soon (5which divides soon (5thth week) to form two branchesweek) to form two branches -- thethe right and leftright and left
bronchial buds.bronchial buds.
x
6 weeks 10 weeks
DEVELOPMENT OF EXTRAPULMONARY BRONCHIDEVELOPMENT OF EXTRAPULMONARY BRONCHI
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TheThe right branchright branch soon divides intosoon divides intothree main branchesthree main branchesand theand the leftleft
branchbranch divides intodivides intotwo main branchestwo main branches (secondary bronchi).(secondary bronchi).
TheThe endodermalendodermal bronchial and lung buds grow in distal and lateral directionsbronchial and lung buds grow in distal and lateral directions
and penetrate theand penetrate thepericardioperitonealpericardioperitoneal canalscanalsfrom which thefrom which the pleuralpleural
cavitycavity develops when it is separated from the peritoneal and pericardialdevelops when it is separated from the peritoneal and pericardial
cavities by projections calledcavities by projections called pleuropericardialpleuropericardial foldsfolds..
x
10 weeks
INTRAPULMONARY BRONCHIAL TREEINTRAPULMONARY BRONCHIAL TREE
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TheThe intrapulmonary bronchial treeintrapulmonary bronchial treedevelops during furtherdevelops during further
dichotomousdichotomousdivisions of thedivisions of thesecondary bronchi to supply thesecondary bronchi to supply the
pulmonary lobes withpulmonary lobes with segmentalsegmental
bronchibronchiand bronchi ofand bronchi oflowerlower
ordersorders..
By the end of theBy the end of the66thth monthmonth
approximatelyapproximately 1717generationsgenerations
of subdivided bronchi are formedof subdivided bronchi are formedto reach the level of respiratoryto reach the level of respiratory
bronchioles.bronchioles.
== PRENATAL STAGEPRENATAL STAGEx
INTRAPULMONARY BRONCHIAL TREEINTRAPULMONARY BRONCHIAL TREE
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AdditionalAdditional 6 generations6 generationsdevelopdevelop
during theduring thePOSTNATAL STAGEPOSTNATAL STAGE
of the lung growth.of the lung growth.
While the trachea and theWhile the trachea and thebronchial tree elongatebronchial tree elongate
the lungsthe lungs migrate caudallymigrate caudally
and by the time of birth theand by the time of birth the
bifurcation of the trachea isbifurcation of the trachea isfound opposite thefound opposite the
44ththThThvertebra.vertebra.
x
INTRAPULMONARY BRONCHIAL TREEINTRAPULMONARY BRONCHIAL TREE
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The bronchial liningThe bronchial lining
epitheliumepithelium andand glandsglandsdevelop from thedevelop from theendodermendoderm
of the lung bud.of the lung bud.
TheThe connective tissueconnective tissue,,
cartilagenouscartilagenous plates and theplates and thesmooth musculature developssmooth musculature develops
from thefrom the surroundingsurrounding
mesenchymemesenchyme..
The visceral and parietalThe visceral and parietalsheets of thesheets of the pleurapleuradevelopdevelop
fromfrom splanchnicsplanchnic and parietaland parietal
layers of thelayers of the mesenchymemesenchyme..x
DEVELOPMENT OF LUNG ALVEOLIDEVELOPMENT OF LUNG ALVEOLI
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Stage 1Stage 1
PSEUDOGLANDULAR PERIODPSEUDOGLANDULAR PERIOD
[ 1[ 1 -- 4 month ]4 month ]
The intrapulmonary airways developThe intrapulmonary airways developinto tubes terminated byinto tubes terminated by aciniacini linedlinedbyby tall columnar epithelial cellstall columnar epithelial cells
( resembling glands ).( resembling glands ).
Blood capillariesBlood capillariesare rare andare rare and
separatedseparated from the liningfrom the liningepithelium by a layer of a looseepithelium by a layer of a looseconnective tissue (no sacs or alveoliconnective tissue (no sacs or alveoliare present.are present.
Respiration is not possible.Respiration is not possible.x
DEVELOPMENT OF LUNG ALVEOLIDEVELOPMENT OF LUNG ALVEOLI
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PSEUDOGLANDULAR PERIODPSEUDOGLANDULAR PERIOD
[ 1[ 1 -- 4 month ]4 month ]x
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Stage 2Stage 2
CANALICULAR PERIODCANALICULAR PERIOD[ 4[ 4 -- 6 month ]6 month ]
LuminaLuminaof the bronchi an terminalof the bronchi an terminal
bronchioles becomebronchioles become largerlarger..
The terminal bronchioles give riseThe terminal bronchioles give rise
toto respiratory bronchiolesrespiratory bronchioles..
Their terminal parts are lined withTheir terminal parts are lined with
simple cuboidal epithelium.simple cuboidal epithelium.
The loose connective tissueThe loose connective tissue
surrounding the terminal airwayssurrounding the terminal airways
isismoremore vascularizedvascularized.. x
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Stage 3Stage 3
TERMINAL SAC PERIODTERMINAL SAC PERIOD
[ 6 month[ 6 month -- full term ]full term ]
ManyManyterminal sacsterminal sacsdevelop anddevelop and
theirtheir epitheliumepitheliumbecomesbecomes very thinvery thin(simple squamous,(simple squamous,type I alveolartype I alveolar
cellscells) =) = primitive alveoli.primitive alveoli.
Type II alveolar cellsType II alveolar cells develop anddevelop and
start to producestart to produce surfactant.surfactant. CapillariesCapillaries begin tobegin to bulgebulgeinto theinto the
primitive alveoli and acquire anprimitive alveoli and acquire an
intimate contactintimate contactwith the flat epithelial cells (respiration is possible).with the flat epithelial cells (respiration is possible).
Lymphatic capillariesLymphatic capillariesdevelop from the loosedevelop from the loose mesenchymalmesenchymal tissue.tissue.x
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Stage 4Stage 4
ALVEOLAR PERIODALVEOLAR PERIOD
[ late fetal[ late fetal -- to 8 years ]to 8 years ]
Alveolar lining attenuates toAlveolar lining attenuates to
extremely thin squamousextremely thin squamous
epithelial layer and many newepithelial layer and many new
alveoli developalveoli develop
Surrounding capillaries protrudeSurrounding capillaries protrude
into the alveoli and theinto the alveoli and the bloodbloodairairbarrier is thinbarrier is thin (ready for(ready forrespiration)respiration)
Mature alveoli do not appearMature alveoli do not appear
before birthbefore birth !!!!!! x
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HISTOGENESISHISTOGENESIS
OF THE LUNGOF THE LUNG
x
PSEUDOGLANDULAR
CANALICULAR TERMINAL SAC
Overview of lung developmentOverview of lung development
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PERINATAL AND POSTNATAL LUNGSPERINATAL AND POSTNATAL LUNGS
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Some discontinuousSome discontinuous breathing movements occur before birthbreathing movements occur before birthand causeand cause
aspiration of some amniotic fluid into the lungs.aspiration of some amniotic fluid into the lungs. Before birth theBefore birth the lungs are filled with fluidlungs are filled with fluidwhich containswhich contains ClCl--, proteins, some, proteins, some
mucus and surfactant. The amount of surfactant increases duringmucus and surfactant. The amount of surfactant increases during
the last two weeks before birth.the last two weeks before birth.
When respiration begins at birth most of theWhen respiration begins at birth most of the lung fluid islung fluid is resorbedresorbedby theby theblood and lymph capillaries. At this stage the surfactant remains depositedblood and lymph capillaries. At this stage the surfactant remains deposited
on the alveolar walls and prevents the alveoli to collapse during expirationon the alveolar walls and prevents the alveoli to collapse during expiration
phase. (In stillborn infant the lung fluid is notphase. (In stillborn infant the lung fluid is not resorbedresorbed -- it sinks whenit sinks when
placed in water.)placed in water.) Respiratory movementsRespiratory movements after birth cause the air to enter the lungsafter birth cause the air to enter the lungs whichwhich
subsequently expand and fill the pleural cavity.subsequently expand and fill the pleural cavity.
TheThe postnatal growth of the lungspostnatal growth of the lungsis mainly due to an increase in the numberis mainly due to an increase in the number
of theof the respiratoryrespiratory bronchiolibronchioli and alveoliand alveoli(first 10 years of the postnatal life).(first 10 years of the postnatal life).x
RESPIRATORY DISTRESS SYNDROME :RESPIRATORY DISTRESS SYNDROME :
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A clinical noteA clinical note::
It may develop in premature infants with weights up to 1.5 kg.It may develop in premature infants with weights up to 1.5 kg.
It is caused by deficiency of the pulmonary surfactant.It is caused by deficiency of the pulmonary surfactant.
The lungs are underinflated (partially collapsed) and the alveoli containThe lungs are underinflated (partially collapsed) and the alveoli contain
a fluid with high protein content and many hyaline membranesa fluid with high protein content and many hyaline membranes
(hyaline membrane disease).(hyaline membrane disease).
The infants develop rapid, labored breathing.The infants develop rapid, labored breathing.
x
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The EndThe End
ThisThispresentationpresentationwaswascompiledcompiledonlyonlyforforinternalinternaluseusebyby
medicalmedicalstudentsstudentsatatthetheFacultyFacultyofofMedicine,Medicine,
PalackPalackUniversity, CZ.University, CZ.
ItItcancannotnotbebedistributeddistributedbybyanyanymeans.means.DK.DK.
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11 3322 44
88
55
66 9977 1010
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1111 12121313 1414 1515
17171616
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Some of the pictures and schematics shown in this presentation were scanned
from the following textbooks or CD ROMs:
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(1) Kierszenbaum A.L.: Histology and Cell biology, Mosby, London, 2002
(2) Fawcett D.W., Jensh R.P.: Concise Histology, Chapman&Hill, New York, 1997
(3) Stevens A., Lowe J.: Human Histology, 2nded., Mosby, London, 2000
(4) Cormack D.H.: Essential Histology, Lippincott-Raven, Philadelphia, 1997
(5) Cohen B.D., Wood D.L.: Structure and Function of the Human Body,
7thed. Lippincott Williams & Wilkins, Philadelphia, 2000
(6) Kerr J.B.: Atlas of Functional Histology, Mosby, London, 2000
(7) Junqueira L.C., Carneiro J., Kelly R.O.: Basic Histology, Text and Atlas
Lange McGraw-Hill, New York, 2003
(8) Gartner L.P., Hiatt J.L.: Color Atlas of Histology, 3rded., Wiliams&Wilkins,
Baltimore, 19949)
(9) Krstic R.V.: Illustrated encyclopedia of Human Histology, Springer Verlag,
Berlin. 1984Reference numbers are given in the right bottom corner of pictures.Reference numbers are given in the right bottom corner of pictures.
Some of the pictures and schematics shown in this presentation were scanned
from the following textbooks or CD ROMs:
REFERENCESREFERENCES
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(10) Ross M.H., Kaye G.I., Pawlina W.: Histology, text and atlas, 4thed., Lippincott
Williams & Wilkins, Philadelphia, 2003
(11) Krstic R.V.: Human Microscopic Anatomy, Atlas for students of Medicine and
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(12) Ross M.H., Reith E.J.: Histology, Text and Atlas, Harper& Row, Lippincott Co.,
New York, 1985
(13) Roroschenko V.P.:Di Fiores Altlas of Histology with Functional correlations, 9thed., Lippincott Williams & Wilkins, Philadelphia, 2000
(14) Lamberti A., MarinoT., Sodicoff M: The Histology lab assistant. Interactive CD-
ROM , AGC Educational Media,
(15) Sadler T.W.: Langmans Medical Embryology, 8thed., Lippincott Williams &
Wilkins, Philadelphia, 2000
(16) Gartner L.P., Hiatt J.L.: Color Textbook of Histology, 2nded., W.B. Saunders Co.,
Philadelphia, 2001
(17) Wheater PR, Burkitt HG, Daniels VG: Functional Histology, text and colour atlas,
2nded., Churchill Livingstone, London, 1987
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Some of the pictures and schematics shown in this presentation were scanned
from the following textbooks or CD ROMs:
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