NERVOUSSYSTEM:GENERALANDSPECIALSENSES

HumanAnatomyUnit4

InAnatomyToday

Receptors

• Receptorsensitivity– Eachreceptorhasacharacteristicsensitivity• Pressure• Pain• Temperature• Chemicalsensitivity

• Receptivefield

StructuralClassification

• Nakednerveendings• Encapsulatednerveendings

• Neuroepithelium– epitheliummodifiedforsomeneuronfunctions

GeneralSenses• Nociceptors– involvedin“pinprick” sensation,itching,tickling

• Thermoreceptors– Respondtochangesintemperature

• Mechanoreceptors– Respondtophysicaldistortion,contact,pressureontheirplasmolemma

• Chemoreceptors– Monitorchemicalcompositionofbodyfluids– Respondtopresenceofspecificchemicals

Nociceptors

• Locations– Numerousinsuperficial

areasofskin– Jointcapsules– Periostea ofbone– Wallsofbloodvessels– Fewindeeptissue,organs

• Respondto– Temperature– Mechanicaldamage– Dissolvedchemicals

• Sensations– Fastpain

• Pricklingpain(cuts)

– Slowpain• Burning,aching

– Referredpain

ReferredPain

• Impulsesfromcertainvisceramappedtoothersitesindermatomesofskin

• Mappedto‘mostlikelysource’

• Usuallyfollowssympatheticnervepathways(canalsofollowparasympatheticpathways)

Thermoreceptors

• Locations– Dermisofskin– Skeletalmuscles– Liver– Hypothalamus

• Coldmorenumerousthanhot• Freenerveendings

Mechanoreceptors

• Respondto:– Stretch– Compressionalforce– Tensileforce– Distortion

• Types– Tactilereceptors– Barroreceptors– Proprioceptors

Chemoreceptors

• Detectsmallchangesintheconcentrationofspecificchemicalorcompounds

• Dissolvedinfluid(plasma)

• Carotid/Aorticbodies

Olfaction

Gustation

• Alltastequalitiesaretastedeverywhereontongue

• Someareasaremoresensitivetocertainqualities

• Canchangeinanindividualwithtime

• Chemoreceptorslocatedintongue

• Fiveprimarysensations– Sweet,sour,salty,bitter,andumami(savory)

Gustation

EquilibriumandHearing• ExternalEar

– Auricle/Pinna– Externalauditorymeatus– Tympanicmembrane– Ceruminousglands

• MiddleEar– Tympaniccavity– Eustaciantube– Auditoryossicles

• Malleus• Incus• Stapes

– Muscles• Tensortympani• Stapediusmuscle

• InnerEar– Membranouslabyrinth

• Containsspecializedcellsthatdetectsoundandmonitorequilibrium

– Bonylabyrinth• fluidfilledcavityofthepetrous

portionofthetemporalbone– Cochlea

• OrganofCorti– Vestibule

• Semicircularcanals• Utricle• Saccule

– Haircells– Supportingcells

AnatomyoftheEar

TheMiddleEar

VestibularApparatus• Semicircularcanals– 3canalsatrightanglestoeachother(anterior,posterior,lateral)

– eachcontains2ampullaewithreceptors– senseangularrotation

• UtricleandSaccule– receptorsforstaticequilibriumchanges– Detectlinearacceleration

SemicircularCanalsandDucts

SemicircularCanalsandDucts

TheMaculaeoftheVestibule

TheCochleaandOrganofCorti

TheCochleaandOrganofCorti

Vision

SectionalAnatomyoftheEye

SectionalAnatomyoftheEye

AccessoryStructuresoftheEye

LacrimalApparatus

ExtrinsicEyeMuscles

TunicsofTheEye

• FibrousTunic– Fibrousoutertunic– composedofscleraproperandcornea

• Vasculartunic– choroid

• Neuraltunic– Retina

FibrousTunic

• Structures– Sclera– Cornea

• Functions–Mechanicalsupport– Physicalprotection– Attachmentforextra-occularmuscles– Assistinaccomodation(focusing)

VascularTunic• Choroid

– Posteriortolens– Networkofcapillaries– Heavilypigmentedwith

melanin• Ciliary body

– heavilypigmented– hasamuscleandprocesses

• Iris– Pigmentedmuscle– 2smoothmusclelayers

• Sphincterpupillae muscle• Dilatorpupillae muscle

– Pupil=holeinmiddle

• Functions– Routeforbloodvessels,

lymphatics– Regulatestheamountoflight

thatenterstheeye– Secretingandreabsorbing

aqueoushumor– Controllingtheshapeofthe

lens(accomodation)

VascularTunic

• Choroid– Posteriortolens– Networkofcapillaries– Heavilypigmentedwithmelanin

• Iris– Pigmentedmuscle– 2smoothmusclelayers

• Pupillarysphinctermuscle

• Pupillarydilatormuscle– Pupil=holeinmiddle

• Ciliary body– heavilypigmented– Ora serrata– Ciliary body

• Ciliary muscle• Ciliary processes

– Suspensory ligaments

VascularTunic

NeuralTunic• Functionoftheretina=photoreception• Pigmentedlayer• Neurallayer– retina– Photoreceptors

• Rods,cones– Maculalutea– foveacentralis

• inlinewiththevisualaxis• “focuspoint”

– opticdisc• blindspot• Exitsiteforbloodvesselsandopticnerve

RetinalOrganization

RetinalOrganization

TheChambersoftheEye

• Anteriorcavity– Anteriorchamber– Posteriorchamber– Aqueoushumor– CanalofSchlemm– Lens

• PosteriorCavity– Vitreouschamber

TheLens

• Composedofalphacrystallineprotein

• Flexible• Bi-convexlens• Accommodates– focusatdifferentdistances