nervous system: general and special senses · nervous system: general and special senses human...
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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