eyes Phisiology

8/20/2019 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

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