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Transcript of eyes Phisiology
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SPECIAL SENSESSPECIAL SENSES(INDERA KHUSUS)(INDERA KHUSUS)
Dr.Milahayati DaulayDr.Milahayati Daulay
Departemen FisiologiDepartemen FisiologiFK USUFK USU
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Eye and AssociatedEye and Associated
StructuresStructures
70% o a!! sensory rece"tors are70% o a!! sensory rece"tors are
in t#e eyein t#e eye
$ost o t#e eye is "rotected y a$ost o t#e eye is "rotected y a
cus#ion o at and t#e ony oritcus#ion o at and t#e ony orit
Accessory structures inc!ude Accessory structures inc!ude
eyero&s' eye!ids' conunctia'eyero&s' eye!ids' conunctia'
!acri*a! a""aratus' and e+trinsic!acri*a! a""aratus' and e+trinsic
eye *usc!eseye *usc!es
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Eyebrows
Coarse hairs that overlie the supraorbitalmargins
Functions include: Shading the eye
Preventing perspiration from reaching the eye
Orbicularis muscle – depresses the
eyebrows Corrugator muscles – move the eyebrows
medially
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Pa!"erae (Eye!ids)
Protect t#e eye anterior!y
Pa!"era! issure , se"arates eye!ids
Cant#i , *edia! and !atera! an-!es(co**issures)
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Palpebrae (Eyelids)Palpebrae (Eyelids)
Lacrimal caruncle – contains glands thatLacrimal caruncle – contains glands that
secrete a whitish, oily secretion (Sandman’ssecrete a whitish, oily secretion (Sandman’s
eye sand)eye sand)
Tarsal plates of connective tissue support theTarsal plates of connective tissue support the
eyelids internallyeyelids internally
Levator palpebrae superioris – gives the upperLevator palpebrae superioris – gives the upper
eyelid mobilityeyelid mobility
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Pa!"erae (Eye!ids)
Eye!as#es
Proect ro* t#e ree *ar-in o eac# eye!id
Initiate re!e+ !in.in-
Luricatin- -!ands associated &it# t#e
eye!ids
$eio*ian -!ands and seaceous -!ands
Ci!iary -!ands !ie et&een t#e #air o!!ic!es
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Pa!"erae (Eye!ids)
Figure !"!b
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ConunctiaConunctia
/rans"arent *e*rane t#at/rans"arent *e*rane t#at
Lines t#e eye!ids as t#e "a!"era! conunctiaLines t#e eye!ids as t#e "a!"era! conunctia
Coers t#e ites o t#e eyes as t#e ocu!arCoers t#e ites o t#e eyes as t#e ocu!ar
conunctiaconunctia
Luricates and "rotects t#e eyeLuricates and "rotects t#e eye
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Lacrimal ApparatusLacrimal Apparatus
• Consists of the lacrimal gland andConsists of the lacrimal gland and
associated ductsassociated ducts
• Lacrimal glands secrete tearsLacrimal glands secrete tears
• TearsTears– Contain mucus, antibodies, and lysozymeContain mucus, antibodies, and lysozyme
– Enter the eye via superolateral excretoryEnter the eye via superolateral excretory
ductsducts
– Exit the eye medially via the lacrimal punctumExit the eye medially via the lacrimal punctum
– Drain into the nasolacrimal ductDrain into the nasolacrimal duct
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Lacri*a! A""aratus
Figure !"#
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Extrinsic Eye MusclesExtrinsic Eye Muscles
Six straplike extrinsic eye musclesSix straplike extrinsic eye musclesEnable the eye to follow moving obectsEnable the eye to follow moving obects
Maintain the shape of the eyeballMaintain the shape of the eyeball
Four rectus muscles originate fromFour rectus muscles originate from
the annular ringthe annular ring
!wo obli"ue muscles move the eye in !wo obli"ue muscles move the eye inthe vertical planethe vertical plane
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E+trinsic Eye $usc!es
Figure !"$a, b
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Su**ary o Crania! Neres and
$usc!e Actions1 Na*es' actions' and crania! nere
inneration o t#e e+trinsic eye *usc!es
Figure !"$c
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Structure o t#e Eyea!!
A s!i-#t!y irre-u!ar #o!!o& s"#ere &it#
anterior and "osterior "o!es
/#e &a!! is co*"osed o t#ree tunics ,
irous' ascu!ar' and sensory
/#e interna! caity is i!!ed &it# !uids
ca!!ed #u*ors
/#e !ens se"arates t#e interna! caity into
anterior and "osterior se-*ents
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Structure o t#e Eyea!!
Figure !"%a
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Fibrous Tunic
2or*s t#e outer*ost coat o t#e eye and is
co*"osed o , 3"a4ue sc!era ("osterior!y) , C!ear cornea (anterior!y)
/#e sc!era "rotects t#e eye and anc#ors
e+trinsic *usc!es /#e cornea !ets !i-#t enter t#e eye
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Vascular Tunic (Uvea): Choroid
Region
Has t#ree re-ions c#oroid' ci!iary ody'
and iris
C#oroid re-ion1 A dar. ro&n *e*rane t#at or*s t#e
"osterior "ortion o t#e uea
1Su""!ies !ood to a!! eye tunics
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5ascu!ar /unic Ci!iary 6ody
A thicened ring of tissuesurrounding the lens
Composed of smooth musclebundles !ciliary muscles"
Anchors the suspensory ligamentthat holds the lens in place
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5ascu!ar /unic Iris
/#e co!ored "art o t#e eye
Pu"i! , centra! o"enin- o t#e iris
Re-u!ates t#e a*ount o !i-#t enterin- t#e eyedurin- C!ose ision and ri-#t !i-#t , "u"i!s constrict
Distant ision and di* !i-#t , "u"i!s di!ate
C#an-es in e*otiona! state , "u"i!s di!ate en t#e
suect *atter is a""ea!in- or re4uires "ro!e*so!in-
s.i!!s
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Pu"i! Di!ation and Constriction
Figure !"&
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Sensory Tunic' etina
A de!icate t&o!ayered *e*rane
Pi-*ented !ayer , t#e outer !ayer t#at
asors !i-#t and "reents its scatterin-
Neura! !ayer' ic# contains P#otorece"tors t#at transduce !i-#t ener-y
6i"o!ar ce!!s and -an-!ion ce!!s
A*acrine and #ori8onta! ce!!s
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Sensory /unic Retina
Figure !"a
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/#e Retina 9an-!ion Ce!!s and
t#e 3"tic Disc
9an-!ion ce!! a+ons
Run a!on- t#e inner surace o t#e retina
Leae t#e eye as t#e o"tic nere
/#e o"tic disc
Is t#e site ere t#e o"tic nere !eaes
t#e eye
Lac.s "#otorece"tors (t#e !ind s"ot)
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/#e Retina 9an-!ion Ce!!s and t#e 3"tic Disc
Figure !"b
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#he $etina: Photoreceptors
$ods: $espond to dim light
Are used for peripheral vision
Cones: $espond to bright light
%ave high&acuity color vision
Are found in the macula lutea
Are concentrated in the fovea centralis
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6!ood Su""!y to t#e Retina
/#e neura! retina receies its !ood
su""!y ro* t&o sources
/#e outer t#ird receies its !ood ro*t#e c#oroid
/#e inner t&ot#irds is sered y t#e
centra! artery and ein
S*a!! esse!s radiate out ro* t#e o"ticdisc and can e seen &it# an
o"#t#a!*osco"e
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Inner C#a*ers and 2!uids
/#e !ens se"arates t#e interna! eye into
anterior and "osterior se-*ents
/#e "osterior se-*ent is i!!ed &it# a c!ear-e! ca!!ed itreous #u*or t#at/rans*its !i-#t
Su""orts t#e "osterior surace o t#e !ens
Ho!ds t#e neura! retina ir*!y a-ainst t#e
"i-*ented !ayer
Contriutes to intraocu!ar "ressure
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Anterior Segment
Co*"osed o t&o c#a*ers ,
Anterior , et&een t#e cornea and t#e iris , Posterior , et&een t#e iris and t#e !ens
A4ueous #u*or , A "!as*a!i.e !uid t#at i!!s t#e anterior se-*ent
, Drains ia t#e cana! o Sc#!e**
Su""orts' nouris#es' and re*oes &astes
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Anterior Se-*ent
Figure !"*
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Lens
A icone+' trans"arent' !e+i!e' aascu!arstructure t#at A!!o&s "recise ocusin- o !i-#t onto t#e retina
Is co*"osed o e"it#e!iu* and !ens iers Lens e"it#e!iu* , anterior ce!!s t#at
dierentiate into !ens iers
Lens iers , ce!!s i!!ed &it# t#e trans"arent
"rotein crysta!!in :it# a-e' t#e !ens eco*es *ore co*"act
and dense and !oses its e!asticity
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LightLight
• Electromagnetic radiation – all energyElectromagnetic radiation – all energy
aves from short gamma rays to longaves from short gamma rays to long
radio avesradio aves
• !ur eyes respond to a small portion of!ur eyes respond to a small portion ofthis spectrum called thethis spectrum called the
visible visible
spectrumspectrum
• Di"erent cones in the retina respondDi"erent cones in the retina respondto di"erent avelengths of the visibleto di"erent avelengths of the visible
spectrumspectrum
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Li-#t
Figure !"+
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#efraction an$ %enses#efraction an$ %enses
&hen light passes from one transparent&hen light passes from one transparent
me$ium to another its spee$ changes an$me$ium to another its spee$ changes an$
it refracts 'ben$s(it refracts 'ben$s( %ight passing through a convex lens 'as in%ight passing through a convex lens 'as in
the eye( is bent so that the rays convergethe eye( is bent so that the rays converge
to a focal pointto a focal point
&hen a convex lens forms an image) the&hen a convex lens forms an image) theimage is upsi$e $own an$ reverse$ right toimage is upsi$e $own an$ reverse$ right to
leftleft
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Reraction and Lenses
Figure !"#
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Focusing 'ight on the $etina
Pathway of light entering the eye: cornea(a)ueous humor( lens( vitreous humor( andthe neural layer of the retina to the
photoreceptors 'ight is refracted: At the cornea
Entering the lens
'eaving the lens
#he lens curvature and shape allow for finefocusing of an image
2 i Di t t 5i i
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2ocusin- or Distant 5ision
1 Li-#t ro* adistance needs!itt!e adust*entor "ro"er
ocusin-1 2ar "oint o
ision , t#edistance eyond
ic# t#e !ensdoes not need toc#an-e s#a"e toocus (;0 t
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2ocusin- or C!ose 5ision2ocusin- or C!ose 5ision
*lose vision re"uires+*lose vision re"uires+ ,ccommo$ation - changing the lens,ccommo$ation - changing the lens
shape by ciliary muscles to increaseshape by ciliary muscles to increase
refractory powerrefractory power *onstriction - the pupillary reex*onstriction - the pupillary reex
constricts the pupils to prevent $ivergentconstricts the pupils to prevent $ivergent
light rays from entering the eyelight rays from entering the eye
*onvergence - me$ial rotation of the*onvergence - me$ial rotation of the
eyeballs towar$ the obect being viewe$eyeballs towar$ the obect being viewe$
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2ocusin- or C!ose 5ision
Figure !"$b
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Pro!e*s o Reraction
E**etro"ic eye , nor*a! eye &it#
!i-#t ocused "ro"er!y
$yo"ic eye (nearsi-#ted) , t#e oca!
"oint is in ront o t#e retina
Corrected &it# a concae !ens
Hy"ero"ic eye (arsi-#ted) , t#e oca!
"oint is e#ind t#e retina
Corrected &it# a cone+ !ens
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Pro!e*s o Reraction
Figure !"%
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RodsRods
2unctiona! c#aracteristics2unctiona! c#aracteristics Sensitie to di* !i-#t and est suited or ni-#tSensitie to di* !i-#t and est suited or ni-#t
isionision
Asor a!! &ae!en-t#s o isi!e !i-#t Asor a!! &ae!en-t#s o isi!e !i-#t Perceied in"ut is in -ray tones on!yPerceied in"ut is in -ray tones on!y
Su* o isua! in"ut ro* *any rods eeds intoSu* o isua! in"ut ro* *any rods eeds into
a sin-!e -an-!ion ce!!a sin-!e -an-!ion ce!! Resu!ts in u88y and indistinct i*a-esResu!ts in u88y and indistinct i*a-es
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*ones*ones
=Functional characteristicsFunctional characteristics
/ee$ bright light for activation 'have low/ee$ bright light for activation 'have low
sensitivity(sensitivity(
0ave pigments that furnish a vivi$ly0ave pigments that furnish a vivi$lycolore$ viewcolore$ view
Each cone synapses with a single ganglionEach cone synapses with a single ganglion
cellcell 1ision is $etaile$ an$ has high resolution1ision is $etaile$ an$ has high resolution
C d R d
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Cones and Rods
Figure !"a
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5i ! P t#5i ! P t#
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5isua! Pat#&ays5isua! Pat#&ays
A+ons o retina! -an-!ion ce!!s or* t#e o"tic nere A+ons o retina! -an-!ion ce!!s or* t#e o"tic nere
$edia! iers o t#e o"tic nere decussate at t#e$edia! iers o t#e o"tic nere decussate at t#eo"tic c#ias*o"tic c#ias*
$ost iers o t#e o"tic tracts continue to t#e$ost iers o t#e o"tic tracts continue to t#e!atera! -enicu!ate ody o t#e t#a!a*us!atera! -enicu!ate ody o t#e t#a!a*us
3t#er o"tic tract iers end in su"erior co!!icu!i3t#er o"tic tract iers end in su"erior co!!icu!i(initiatin- isua! re!e+es) and "retecta! nuc!ei(initiatin- isua! re!e+es) and "retecta! nuc!ei(ino!ed &it# "u"i!!ary re!e+es)(ino!ed &it# "u"i!!ary re!e+es)
3"tic radiations trae! ro* t#e t#a!a*us to t#e3"tic radiations trae! ro* t#e t#a!a*us to t#e
isua! corte+isua! corte+
5isua! Pat#&ays
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5isua! Pat#&ays