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C h a p t e r 9 The General and Special Senses C h a p t e r 9 The General and Special Senses

C h a p t e r 9 The General and Special Senses - PowerPoint Presentation

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C h a p t e r 9 The General and Special Senses - PPT Presentation

PowerPoint Lecture Slides prepared by Jason LaPres Lone Star College North Harris Copyright 2010 Pearson Education Inc 91 Sensory receptors connect our internal and external environments with the nervous system ID: 745994

receptors figure eye sensory figure receptors sensory eye pressure taste olfactory visual ear sensations cells touch equilibrium information provide

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Slide1

C h a p t e r9The General and Special Senses

PowerPoint® Lecture Slides prepared by Jason LaPres

Lone Star College - North Harris

Copyright © 2010 Pearson Education, Inc.Slide2

9-1: Sensory receptors connect our internal and external environments with the nervous systemSlide3

Sensory ReceptorsSpecialized cells that monitor specific conditions in the body or external environmentWhen stimulated, a receptor passes information to the CNS in the form of action potentials along the axon of a sensory neuronSlide4

Sensory ReceptorsSensationThe arriving information from these sensesPerceptionConscious awareness of a sensationSlide5

Sensory ReceptorsThe Detection of StimuliReceptor sensitivity:Each receptor has a characteristic sensitivityReceptive field:Area is monitored by a single receptor cell

The larger the receptive field, the more difficult it is to localize a stimulusSlide6

Receptors and Receptive FieldsFigure 9-1 Slide7

Sensory ReceptorsThe Interpretation of Sensory InformationArriving stimulus: Takes many forms:physical force (such as pressure)

dissolved chemicalsound

lightSlide8

Sensory ReceptorsThe Interpretation of Sensory Information Sensations: Taste, hearing, equilibrium, and vision provided by specialized receptor cellsCommunicate with sensory neurons across chemical synapsesSlide9

Sensory ReceptorsAdaptationReduction in sensitivity of a constant stimulusYour nervous system quickly adapts to stimuli that are painless and constant

For example think about the background music at a doctor’s officeSlide10

Sensory ReceptorsGeneral Senses Describe our sensitivity to:TemperaturePainTouchPressure

VibrationProprioceptionSlide11

Sensory ReceptorsSpecial SensesOlfaction (smell)Vision (sight)Gustation (taste)Equilibrium (balance)HearingSlide12

Sensory ReceptorsStimulation of a receptor produces action potentials along the axon of a sensory neuron The frequency and pattern of action potentials contain information about the strength, duration, and variation of the stimulus Your perception of the nature of that stimulus depends on the path it takes inside the CNSSlide13

9-2: General sensory receptorscan be classified by the typeof stimulus that excites themSlide14

Classifying Sensory ReceptorsGeneral sensory receptors are divided into four types by the nature of the stimulus that excites themNociceptors (pain)

Thermoreceptors (temperature)Slide15

Classifying Sensory ReceptorsMechanoreceptors (physical distortion)Tactile receptors

(touch)Baroreceptors (pressure)

Proprioceptors (position)Chemoreceptors (chemical concentration)Slide16

PainNociceptors (also called pain receptors)Are common in the superficial portions of the skin, joint capsules, within the periostea of bones, and around the walls of blood vessels

May be sensitive to temperature extremes, mechanical damage, and dissolved chemicals, such as chemicals released by injured cells

Figure 15–2Slide17

PainNociceptors Are free nerve endings with large receptive fields:Branching tips of dendrites

Not protected by accessory structures Can be stimulated by many different stimuli

Two types of axons: Type A and Type C fibersSlide18

PainNociceptors Myelinated Type A fibers: Carry sensations of fast pain, or prickling pain, such as that caused by an injection or a deep cutSensations reach the CNS quickly and often trigger somatic reflexes

Relayed to the primary sensory cortex and receive conscious attentionSlide19

PainNociceptors Type C fibers:Carry sensations of slow pain, or burning and aching painCause a generalized activation of the reticular formation and thalamus

You become aware of the pain but only have a general idea of the area affectedSlide20

Referred PainFigure 9-2Slide21

TemperatureThermoreceptors Also called temperature receptorsAre free nerve endings located in:

The dermisSkeletal musclesThe liver

The hypothalamusSlide22

TemperatureThermoreceptors Temperature sensations:Conducted along the same pathways that carry pain sensations

Sent to:the reticular formation (RAS)

the thalamusthe primary sensory cortex (to a lesser extent)Slide23

Touch, Pressure, and PositionMechanoreceptors Sensitive to stimuli that distort their plasma membranesContain mechanically gated ion channels whose gates open or close in response to

StretchingCompressionTwisting

Other distortions of the membraneSlide24

Touch, Pressure, and PositionTactile receptorsProvide the sensations of touch, pressure, and vibration:Touch sensations provide information about shape or texturePressure sensations indicate degree of mechanical distortion

Vibration sensations indicate pulsing or oscillating pressureSlide25

Tactile Receptors in the SkinFigure 9-3

Sensitive to touch and pressureSlide26

Tactile Receptors in the SkinFigure 9-3

Monitor movement and changes across the surface of your bodySlide27

Tactile Receptors in the SkinFigure 9-3

Fine touch & pressure receptorsSlide28

Tactile Receptors in the Skin

Figure 9-3

Aka Meissner’s corpuscles

Fine touch & pressure, low freq vibrationSlide29

Tactile Receptors in the Skin

Figure 9-3

Aka Pacinian corpusclesSensitive to deep pressure, pulses or high freq vibrationSlide30

Tactile Receptors in the Skin

Figure 9-3

Sensitive to pressure & skin distortion but located deep in the dermisSlide31

Touch, Pressure, and PositionBaroreceptors Monitor change in pressureConsist of free nerve endings that branch within elastic tissues in wall of distensible organ (such as a blood vessel)

Respond immediately to a change in pressure, but adapt rapidlySlide32

BaroreceptorsFigure 9-4Slide33

Touch, Pressure, and PositionProprioceptors Monitor:Position of jointsTension in tendons and ligaments

State of muscular contractionSlide34

Touch, Pressure, and PositionMajor Groups of Proprioceptors Muscle spindles: Monitor skeletal muscle length Trigger stretch reflexes

Golgi tendon organs:Located at the junction between skeletal muscle and its tendon

Stimulated by tension in tendonMonitor external tension developed during muscle contractionSlide35

Chemical DetectionChemoreceptors Respond only to water-soluble and lipid-soluble substances dissolved in surrounding fluidReceptors exhibit peripheral adaptation over period of secondsSlide36

Classifying Sensory ReceptorsChemoreceptors Located in the: Carotid bodies:

near the origin of the internal carotid arteries on each side of the neckAortic bodies

: between the major branches of the aortic archReceptors monitor pH, carbon dioxide, and oxygen levels in arterial bloodSlide37

ChemoreceptorsFigure 9-5Slide38

9-3: Olfaction, the sense of smell,involves olfactory receptorsresponding to chemical stimuliSlide39

Figure 17–1aSmell (Olfaction)

Olfactory OrgansProvide sense of smell

Located in nasal cavity on either side of nasal septumMade up of two layers:Olfactory epithelium Lamina propria Slide40

The Olfactory Organs

Figure 9-6Slide41

The Olfactory OrgansSlide42

Smell (Olfaction)Olfactory Glands Secretions coat surfaces of olfactory organsOlfactory ReceptorsHighly modified neurons

Olfactory reception:Involves detecting dissolved chemicals as they interact with odorant-binding proteinsSlide43

Smell (Olfaction)Olfactory PathwaysAxons leaving olfactory epithelium: Collect into 20 or more bundlesPenetrate cribriform plate of ethmoid

Reach olfactory bulbs of cerebrum where first synapse occursAxons leaving olfactory bulb:

travel along olfactory tract to reach olfactory cortex, hypothalamus, and portions of limbic systemSlide44

Smell (Olfaction)Olfactory DiscriminationCan distinguish thousands of chemical stimuliCNS interprets smells by the pattern of receptor activityOlfactory Receptor Population

Considerable turnoverNumber of olfactory receptors declines with ageSlide45

9-4: Gustation, the sense of taste, involves taste receptors responding to chemical stimuliSlide46

Taste (Gustation)Gustation provides information about the foods and liquids consumedTaste receptors (or gustatory receptors) are distributed on tongue and portions of pharynx and larynx

Clustered into taste budsSlide47

Taste (Gustation)Taste budsAssociated with epithelial projections (lingual papillae) on superior surface of tongueThree types of lingual papillae:Filiform papillae:

provide frictiondo not contain taste buds

Fungiform papillae: contain five taste buds eachCircumvallate papillae: contain 100 taste buds eachSlide48

Gustatory ReceptorsFigure 9-7Slide49

Gustatory ReceptorsSlide50

Taste (Gustation)Gustatory DiscriminationPrimary taste sensations:SweetSaltySourBitterUmami (savory)Slide51

Taste (Gustation)Additional human taste sensationsWater:Detected by water receptors

in the pharynxSlide52

Taste (Gustation)Gustatory Discrimination Dissolved chemicals contact taste hairsBind to receptor proteins of gustatory cellSalt and sour receptors:

Chemically gated ion channels Stimulation produces depolarization of cell

Sweet, bitter, and umami stimuli:G proteins:gustducinsSlide53

9-5: Internal eye structurescontribute to vision, while accessory eye structures provide protectionSlide54

Accessory Structures of the Eye Provide protection, lubrication, and supportIncludesThe

palpebrae (eyelids) The superficial epithelium of eye

The lacrimal apparatus

The Eye: Accessory StructuresSlide55

Accessory Structures of the Eye

Figure 9-8aSlide56

Accessory Structures of the Eye

Figure 9-8bSlide57

The EyeThree Layers of the EyeOuter fibrous tunicMiddle vascular tunicInner neural tunic

EyeballIs hollowIs divided into two cavities:

Large posterior cavitySmaller anterior cavitySlide58

The Extrinsic Eye MusclesFigure 9-9

Eye Muscles 3D RotationSlide59
Slide60

The Eye

Figure 9-10aSlide61

The Eye

Figure 9-10bSlide62

Figure 9-10cSlide63

The EyeThe Fibrous Tunic Sclera (white of eye)CorneaLimbus (border between cornea and sclera) Slide64

The EyeVascular Tunic (Uvea) Functions Provides route for blood vessels and lymphatics that supply tissues of eyeRegulates amount of light entering eye

Secretes loose and reabsorbs aqueous humor that circulates within chambers of eyeControls shape of lens, which is essential to focusingSlide65

The Pupillary MusclesFigure 9-11Slide66

The EyeThe Neural Tunic (Retina) Outer layer called pigmented partInner neural part:Contains visual receptors and associated neuronsRods and cones are types of photoreceptors:

rods:do not discriminate light colorshighly sensitive to light

cones:provide color visiondensely clustered in fovea, at center of macula luteaSlide67

Retinal OrganizationFigure 9-12Slide68

Retinal Organization

Figure 9-12Slide69

Retinal OrganizationFigure 9-12

Blind SpotSlide70

The Blind SpotSlide71

The EyeThe Neural Tunic (Retina) Inner neural part: Bipolar cells: neurons of rods and cones synapse with ganglion cells

Horizontal cells:extend across outer portion of retina

Amacrine cells:comparable to horizontal cell layerwhere bipolar cells synapse with ganglion cells

Figure 17–6aSlide72

The EyeThe Chambers of the EyeCiliary body and lens divide eye into:Large posterior cavity (vitreous chamber)

Smaller anterior cavity:anterior chamber:

extends from cornea to irisposterior chamber: between iris, ciliary body, and lensSlide73

The EyeSmaller anterior cavity Aqueous humor:Fluid circulates within eyeDiffuses through walls of anterior chamber into

canal of Schlemm Re-enters circulation

Intraocular pressure:Fluid pressure in aqueous humor Helps retain eye shapeSlide74

The EyeLarge Posterior Cavity (Vitreous Chamber)Vitreous body: Gelatinous mass Helps stabilize eye shape and supports retinaSlide75

The Eye ChambersFigure 9-14

Ciliary MusclesSlide76

The EyeThe LensLens fibers:Cells in interior of lensNo nuclei or organellesSlide77

The EyeThe LensLight refraction:Bending of light by cornea and lens Focal point:

specific point of intersection on retinaFocal distance:

distance between center of lens and focal pointSlide78

The EyeFigure 9-15Slide79

The EyeLight Refraction of LensAccommodation:Shape of lens changes to focus image on retina Astigmatism:

Condition where light passing through cornea and lens is not refracted properly Visual image is distorted

Visual acuity:Clarity of vision“Normal” rating is 20/20

Path of LightSlide80

The Eye

Figure 9-15Slide81

Image Formation

Figure 9-16Slide82

Myopia (Nearsightedness)Slide83

Hyperopia (Farsightedness)Slide84

Image Formation & Visual AbnormalitiesEmmetropia is normal, focused vision.Slide85

9-6: Photoreceptors respondto light and change it intoelectrical signals essentialto visual physiologySlide86

Visual PhysiologyRods Respond to almost any photon, regardless of energy contentCones Have characteristic ranges of sensitivitySlide87

Visual PhysiologyAnatomy of Rods and ConesOuter segment with membranous discsInner segment:Narrow stalk connects

outer segment to inner segment

Visual pigments:Is where light absorption occursDerivatives of rhodopsin

(opsin plus retinal)Retinal: synthesized from vitamin ASlide88

Figure 9-19Slide89

Visual PhysiologyPhotoreceptionPhoton strikes retinal portion of rhodopsin molecule embedded in membrane of discOpsin is activatedBound retinal molecule has two possible configurations:

11-cis form

11-trans formSlide90

Visual Physiology

Figure 9-20Slide91

Figure 17–16Visual Physiology

Color VisionIntegration of information from red, green,

and blue conesColor blindness:Inability to detect certain colorsSlide92

Color Vision

The colors of the rainbow as viewed by a person with no color vision deficiencies.

The colors of the rainbow as viewed by a person with protanopia – affects red receptors

The colors of the rainbow as viewed by a person with deuteranopia – affects green receptors

The colors of the rainbow as viewed by a person with tritanopia – affects blue- yellow receptorsSlide93

Color BlindnessColor vision deficiency, is the inability to perceive differences between some of the colors that others can distinguish. It is most often of genetic nature, but may also occur because of eye, nerve, or brain damage, or exposure to certain chemicals.Slide94

Example of an Ishihara color test plates.Slide95

Visual PhysiologyLight and Dark AdaptationDark:Most visual pigments are fully receptive to stimulationLight:

Pupil constrictsBleaching of visual pigments occursSlide96

Visual PhysiologyThe Visual PathwaysBegin at photoreceptorsEnd at visual cortex of cerebral hemispheresMessage crosses two synapses before it heads toward brain:

Photoreceptor to bipolar cellBipolar cell to ganglion cell Slide97

Figure 9-21Slide98

9-7: Equilibrium sensationsoriginate within the inner ear, while hearing involves the detection and interpretation of sound wavesSlide99

Anatomy of the Ear The External EarAuricle:Surrounds entrance to external acoustic meatus

Protects opening of canal

Provides directional sensitivityExternal acoustic meatus:Ends at tympanic membrane (eardrum)Tympanic membrane:

Is a thin, semitransparent sheetSeparates external ear from middle earSlide100

The Anatomy of the Ear

Figure 9-22

Ear AnatomySlide101

The EarThe Middle Ear Also called tympanic cavity Communicates with nasopharynx via auditory tube:

Permits equalization of pressures on either side of tympanic membraneEncloses and protects three auditory ossicles:

Malleus (hammer)Incus (anvil)Stapes (stirrup)Slide102

The Structure of the Middle Ear

Figure 9-23Slide103

The EarThe Inner Ear Contains fluid called endolymph Bony labyrinth surrounds and protects membranous labyrinthSubdivided into:

VestibuleSemicircular canals

CochleaSlide104

Figure 9-24

The Inner EarSlide105

The EarThe Inner Ear Vestibule:Encloses saccule and utricle Receptors provide sensations of gravity and linear acceleration

Semicircular canals:Contain semicircular ducts

Receptors stimulated by rotation of headCochlea:Contains cochlear duct (elongated portion of membranous labyrinth)

Receptors provide sense of hearingSlide106

The EarThe Inner Ear Round window: Thin, membranous partitionSeparates perilymph from air spaces of middle ear

Oval window:Formed of collagen fibers

Connected to base of stapes Slide107

Equilibrium Sensations provided by receptors of vestibular complexHair cellsBasic receptors of inner ear

Provide information about direction and strength of mechanical stimuli

BalanceSlide108

Equilibrium The Semicircular Ducts Are continuous with utricleEach duct contains:

Ampulla with gelatinous cupula

Associated sensory receptorsStereocilia — resemble long microvilli:are on surface of hair cell

Kinocilium — single, large ciliumSlide109

The Semicircular Ducts

Figure 9-25 a,b,cSlide110

Equilibrium The Utricle and Saccule Provide equilibrium sensationsAre connected with the endolymphatic duct, which ends in endolymphatic sac

Maculae:Oval structures where hair cells cluster

Statoconia:Densely packed calcium carbonate crystals on surface of gelatinous massOtolith (ear stone) = gel and statoconiaSlide111

Equilibrium

Figure 9-25 a,dSlide112

Equilibrium

Figure 9-25 eSlide113

Pathways for Equilibrium SensationsVestibular receptorsActivate sensory neurons of vestibular ganglia Axons form vestibular branch of vestibulocochlear nerve (VIII)

Synapse within vestibular nuclei Slide114

HearingCochlear duct receptors Provide sense of hearingSlide115

Figure 9-26 a

The Cochlea and Organ of CortiSlide116

Figure 9-26 b

The Cochlea and Organ of CortiSlide117

HearingAuditory Ossicles Convert pressure fluctuation in air into much greater pressure fluctuations in perilymph of cochleaFrequency of sound:Determined by which part of cochlear duct is stimulated

Intensity (volume):Determined by number of

hair cells stimulated

Hearing ReceptorsSlide118

Sound and Hearing

Figure 9-27Slide119

Sound and Hearing

Figure 9-27Slide120

HearingAuditory PathwaysCochlear branch:Formed by afferent fibers of spiral ganglion neurons:

enters medulla oblongata synapses at dorsal and ventral cochlear nuclei information crosses to opposite side of brain:

ascends to inferior colliculus of mesencephalon

Figure 17–31Slide121

HearingAuditory PathwaysAscending auditory sensations:Synapse in medial geniculate nucleus of thalamusProjection fibers deliver information to auditory cortex of temporal lobeSlide122

Pathways for Auditory Sensations

Figure 9-28 Slide123

9-8: Aging is accompaniedby a noticeable decline inthe special sensesSlide124

Smell and AgingOlfactory neuron recycling slows, leading to decreased sensitivitySlide125

Taste and AgingNumber of taste buds is reduced, and sensitivity is lostSlide126

Vision and AgingLens stiffensLens cloudsBlood vessels grow in retinaSlide127

Hearing and AgingLoss of elasticity in tympanic membrane