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
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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 RotationSlide59Slide60
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