Upload
theslaps
View
1.098
Download
0
Tags:
Embed Size (px)
Citation preview
© 2012 Pearson Education, Inc.
18The Nervous System: General and Special Senses
PowerPoint® Lecture Presentations prepared bySteven BassettSoutheast Community College Lincoln, Nebraska
© 2012 Pearson Education, Inc.
Introduction
• Stimulation of the receptor directly or indirectly alters the production of action potentials in a sensory neuron.
• The sensory information arriving at the CNS is called a sensation.
• A perception is a conscious awareness of a sensation.
• Sensory receptors are the interface between the nervous system and the internal and external environment
© 2012 Pearson Education, Inc.
Receptors
• General senses• Refers to temperature, pain, touch, pressure, vibration,
and proprioception• Receptors throughout the body• These sensations arrive at the primary sensory cortex, or
somatosensory cortex• Special senses • Sensations of smell (olfaction), taste (gustation), balance
(equilibrium), hearing, and vision• Specialized receptor cells that are structurally more
complex than those of the general senses
© 2012 Pearson Education, Inc.
Figure 18.1 Receptors and Receptive Fields
Receptive fields
Receptivefield 1
Receptivefield 2
© 2012 Pearson Education, Inc.
Receptors
• Receptor specificity — each receptor responds to one type of stimulus
• Receptive field — the area that a receptor monitors• Tonic receptors — always send signals, thus information
is based on the frequency of the action potentials• Phasic receptors — send action potentials only
if stimulated• Peripheral adaptation — receptors may stop
sending AP even if the stimulus is still present• Central adaptation — CNS ignoring a AP from
a receptor
© 2012 Pearson Education, Inc.
The General Senses
• Classification of the General Senses• One classification scheme:
• Exteroceptors: provide information about the external environment
• Proprioceptors: provide information about the position of the body
• Interoceptors: provide information about the inside of the body
© 2012 Pearson Education, Inc.
The General Senses
• Sensory Limitations• Humans do not have receptors for every
possible stimulus.• Our receptors have characteristic ranges of
sensitivity.• A stimulus must be interpreted by the CNS.
Our perception of a particular stimulus is an interpretation and not always a reality.
© 2012 Pearson Education, Inc.
The General Senses
• Receptors for general senses classified by location:• Exteroceptors provide information about the external
environment.• Proprioceptors monitor body position.• Interoceptors monitor conditions inside the body.• Receptors for general senses classified by type
of stimulus:• Nociceptors = tissue damage• Thermoreceptors = change in temperature• Mechanoreceptors = physical distortion, contact, or
pressure • Chemoreceptors = chemical composition of body fluids
© 2012 Pearson Education, Inc.
The General Senses
• Mechanoreceptors• Encapsulated tactile receptors
• Tactile corpuscle: common on eyelids, lips, fingertips, nipples, and genitalia
• Ruffini corpuscle: in the dermis, sensitive to pressure and distortion
• Lamellated corpuscle: consists of concentric cellular layers / sensitive to vibrations
© 2012 Pearson Education, Inc.
Figure 18.3e Tactile Receptors in the Skin
Capsule
Dendrites
Ruffini corpuscle
Sensorynerve fiber
Collagenfibers
Hair
Root hair plexus
Lamellated corpuscle
Ruffini corpuscle
Merkel cells andtactile discs
Tactilecorpuscle
Free nerveending
Sensorynerves
© 2012 Pearson Education, Inc.
Figure 18.3f Tactile Receptors in the Skin
Lamellated corpuscle
Dendriticprocess
Concentric layers (lamellae)of collagen fibersseparated by fluid
Concentric layers (lamellae)of collagen fibersseparated by fluid
Accessory cells(specialized fibrocytes)
Dendritic process
Dermis
LM 125Lamellated corpuscle
Hair
Root hair plexus
Lamellated corpuscle
Ruffini corpuscle
Merkel cells andtactile discs
Tactilecorpuscle
Free nerveending
Sensorynerves
© 2012 Pearson Education, Inc.
Figure 18.4 Baroreceptors and the Regulation of Autonomic Functions
Provide information on volume oftract segments, trigger reflexmovement of materials along tract
Provide information on volume ofurinary bladder, trigger urinary reflex
Baroreceptors of BladderWall
Baroreceptors of DigestiveTract
Baroreceptors of CarotidSinus and Aortic Sinus
Baroreceptors of Lung
Baroreceptors of Colon
Provide information on bloodpressure to cardiovascular andrespiratory control centers
Provide information on lungstretching to respiratoryrhythmicity centers forcontrol of respiratory rate
Provide information on volume of fecal material in colon, trigger defecation reflex
© 2012 Pearson Education, Inc.
Figure 18.5 Chemoreceptors
Carotid body LM 1500
Blood vesselChemoreceptive
neuronsTrigger reflexiveadjustments in
depth and rate ofrespiration
Trigger reflexiveadjustments inrespiratory andcardiovascular
activity
Via cranialnerve IX
Via cranialnerve X
Sensitive to changes in pHand PCO2
in cerebrospinal
fluid
Sensitive to changes in pH,PCO2
, and PO2 in blood
Sensitive to changes in pH, PCO2
, and PO2 in blood
Chemoreceptors in andnear Respiratory Centersof Medulla Oblongata
Chemoreceptors of Carotid Bodies
Chemoreceptors of Aortic Bodies
© 2012 Pearson Education, Inc.
The Special Senses
• The special senses include:• Olfaction (smell)• Gustation (taste)• Equilibrium • Hearing• Vision
© 2012 Pearson Education, Inc.
Olfaction (Smell)
• Olfaction• Olfactory organs• Nasal cavity
• Olfactory epithelium• Bipolar olfactory receptors (N I)• Supporting cells• Basal cells (stem cells)• Lamina propria
• Olfactory glands (Bowman’s glands)• Blood vessels• Nerves (axons of N I)
© 2012 Pearson Education, Inc.
Figure 18.6a The Olfactory Organs
The distribution of the olfactory receptorson the left side of the nasal septum isshown by the shading.
Olfactorybulb
Olfactory nervefibers (N I)
Olfactorytract
Cribriform plateof ethmoid
Olfactoryepithelium
© 2012 Pearson Education, Inc.
Figure 18.6b The Olfactory Organs
A detailed view of the olfactory epithelium
Substance being smelled
Olfactoryepithelium
Laminapropria
Cribriformplate
Knob
Olfactory cilia:surfaces containreceptor proteins
Mucous layer
Supporting cell
Olfactoryreceptor cell
Developing olfactoryreceptor cell
Olfactorynerve fibers
To olfactorybulb
Olfactory(Bowman’s)
gland
Regenerative basal cell:divides to replace worn-out
olfactory receptor cells
© 2012 Pearson Education, Inc.
Gustation (Taste)
• Gustation • The tongue consists of papillae• Papillae consist of taste buds• Taste buds consist of gustatory cells• Each gustatory cell has a slender microvilli
that extends through the taste pore into the surrounding fluid
© 2012 Pearson Education, Inc.
Gustation (Taste)
• Gustation Pathways• Dissolved chemicals contact the taste hairs
(microvilli)• Impulses go from the gustatory cell through
CN VII, IX, and X• The impulses eventually arrive at the cerebral
cortex
© 2012 Pearson Education, Inc.
Figure 18.8 Gustatory Pathways
Gustatorycortex
ThalamicnucleusMediallemniscus
Nucleussolitarius
Vagus nerve(N X)
Facial nerve(N VII)
Glossopharyngealnerve (N IX)
© 2012 Pearson Education, Inc.
Gustation (Taste)
Gustatory receptors are clustered in taste buds, which contain gustatory cells that extend taste hairs through a taste pore.Three types of papillae (epithelial projections) on human tongue:
Filiform Fungiform Circumvallate
Four primary tastes: Salty Bitter Sweet Sour
Also water and umami (characteristic of broth)
© 2012 Pearson Education, Inc.
© 2012 Pearson Education, Inc.
Equilibrium and Hearing
The Ear External ear Middle ear
Auditory ossicles Auditory tube
Inner ear Vestible and semicircular canals
Equilibrium Cochlea
Hearing
ANIMATION The Ear: Ear Anatomy
© 2012 Pearson Education, Inc.
Figure 18.9 Anatomy of the Ear
EXTERNAL EAR MIDDLE EAR INNER EAR
Auricle
Auditory ossicles Semicircularcanals
Petrous partof temporal
bone
Facial nerve(N VII)
Externalacousticmeatus
Elasticcartilage
Tympanicmembrane
Tympaniccavity
Oval window
Round window
Vestibule
Auditory tube
Cochlea
Tonasopharynx
Bony labyrinthof inner ear
Vestibulocochlearnerve (N VIII)
© 2012 Pearson Education, Inc.
Figure 18.9 Anatomy of the Ear
EXTERNAL EAR MIDDLE EAR INNER EAR
Auricle
Auditory ossicles Semicircularcanals
Petrous partof temporal
bone
Facial nerve(N VII)
Externalacousticmeatus
Elasticcartilage
Tympanicmembrane
Tympaniccavity
Oval window
Round window
Vestibule
Auditory tube
Cochlea
Tonasopharynx
Bony labyrinthof inner ear
Vestibulocochlearnerve (N VIII)
© 2012 Pearson Education, Inc.
Figure 18.12a Semicircular Canals and Ducts
Anterior view of the bonylabyrinth cut away to show thesemicircular canals and theenclosed semicircular ducts ofthe membranous labyrinth
Cochlear duct
Vestibular duct
Saccule
Utricle
Tympanicduct
Organ ofCorti
Cochlea
Endolymphatic sacMaculae
Cristae within ampullae
Bony labyrinth
Membranouslabyrinth
KEY
Vestibule
Anterior
Lateral
Posterior
Semicircularcanal
Semicircularducts
© 2012 Pearson Education, Inc.
Figure 18.13 The Function of the Semicircular Ducts, Part I
Anterior view ofthe maculae andsemicircular ductsof the right side
A section through the ampulla of asemicircular duct
Endolymph movement along thelength of the duct moves the cupulaand stimulates the hair cells.
Structure of a typical hair cell showing detailsrevealed by electron microscopy. Bending thestereocilia toward the kinocilium depolarizes the celland stimulates the sensory neuron. Displacement inthe opposite direction inhibits the sensory neuron.
Supporting cell
Sensory nerveending
Hair cell
StereociliaKinocilium
Displacement inthis direction inhibits hair cell
Displacement inthis direction
stimulates hair cell
At rest
AmpullaSemicircular duct
Direction ofduct rotation
Direction of relativeendolymph movement
Direction ofduct rotation
Crista
Hair cells
Ampullafilled with
endolymphCupula
Supporting cells
Sensory nerve
Saccule Maculae
Utricle
AmpullaAnteriorPosterior
Lateral
Semicircularducts
Vestibular branch (N VIII)
Cochlea
Endolymphatic sac
Endolymphatic duct
© 2012 Pearson Education, Inc.
Figure 18.15ab The Maculae of the Vestibule
A scanning electron micrograph showing the crystalline structure of otoliths
Detailed structure of a sensory macula
Otolith
Gelatinousmaterial
Statoconia
Hair cells
Nerve fibers
Statoconia
Otolith
© 2012 Pearson Education, Inc.
Figure 18.16 Neural Pathways for Equilibrium Sensations
Semicircularcanals
Vestibularganglion
Vestibularbranch
Vestibule
Cochlearbranch
Vestibulocochlear nerve(N VIII)
Vestibulospinaltracts
Tocerebellum
Vestibular nucleus
To superior colliculus andrelay to cerebral cortex
Red nucleus
N III
N IV
N VI
N XI
© 2012 Pearson Education, Inc.
Equilibrium and Hearing
• The Cochlea• Consists of “snail-shaped” spirals• Spirals coil around a central area called the
modiolus• Within the modiolus are sensory neurons• The sensory neurons are associated with CN
VIII• Organ of Corti
© 2012 Pearson Education, Inc.
© 2012 Pearson Education, Inc.
Figure 18.17ab The Cochlea and Organ of Corti
Structure of the cochlea within the temporalbone showing the turns of the vestibular duct,cochlear duct, and tympanic duct
Structure of the cochlea in partialsection
KEY
From tip of spiralto round window
From oval windowto tip of spiral
Round window
Stapes atoval window
Semicircularcanals
Vestibulocochlearnerve (VIII)
Cochlearbranch
Vestibularbranch
Tympanic duct
Vestibular duct
Cochlear duct
Apical turn
Spiral ganglion
Modiolus
Vestibular membrane
Tectorial membrane
Basilar membrane
Middle turn
Vestibular duct (scalavestibuli—contains perilymph)
Organ of Corti
Cochlear duct (scalamedia—contains endolymph)
Tympanic duct (scalatympani—contains perilymph)
Basal turn
Temporal bone (petrous part)
Cochlear nerve
Vestibulocochlear nerve (VIII)From ovalwindow
To roundwindow
© 2012 Pearson Education, Inc.
Figure 18.17d–f The Cochlea and Organ of Corti
A color-enhanced SEMshowing a portion of thereceptor surface of theorgan of Corti
Diagrammatic and histological sections through thereceptor hair cell complex of the organ of Corti
Three-dimensional sectionshowing the detail of the cochlearchambers, tectorial membrane,and organ of Corti
Bony cochlear wall
Vestibular duct
Vestibular membrane
Cochlear duct
Tectorial membrane
Basilar membrane
Tympanic duct
Organ of Corti
Spiralganglion
Cochlear branchof N VIII
Cochlear duct (scala media)
Vestibular membrane
Tectorial membrane
Organ of Corti LM 125
Tympanic duct(scala tympani)
Basilarmembrane
Hair cellsof organof Corti
Spiral ganglioncells of
cochlear nerve
Tectorial membrane
Outerhair cell
Basilar membrane Inner hair cell Nerve fibers
Stereocilia of inner hair cells
Stereocilia of outer hair cells
Surface of the organ of Corti SEM 1320
© 2012 Pearson Education, Inc.
Figure 18.17de The Cochlea and Organ of Corti
Diagrammatic and histological sections through thereceptor hair cell complex of the organ of Corti
Three-dimensional sectionshowing the detail of the cochlearchambers, tectorial membrane,and organ of Corti
Bony cochlear wall
Vestibular duct
Vestibular membrane
Cochlear duct
Tectorial membrane
Basilar membrane
Tympanic duct
Organ of Corti
Spiralganglion
Cochlear branchof N VIII
Cochlear duct (scala media)
Vestibular membrane
Tectorial membrane
Organ of Corti LM 125
Tympanic duct(scala tympani)
Basilarmembrane
Hair cellsof organof Corti
Spiral ganglioncells of
cochlear nerve
Tectorial membrane
Outerhair cell
Basilar membrane Inner hair cell Nerve fibers
© 2012 Pearson Education, Inc.
Figure 18.18 Pathways for Auditory Sensations
KEYFirst-order neuronSecond-order neuronThird-order neuronFourth-order neuron
High-frequencysounds
Low-frequencysounds
Cochlea
Cochlear branch
Vestibulocochlearnerve (N VIII)
Cochlear nuclei
Vestibularbranch
To ipsilateralauditory cortex
Superior olivary nucleus
Motor output to spinalcord through thetectospinal tracts
Motor outputto cranial
nerve nuclei
Inferior colliculus(mesencephalon)
Medial geniculatenucleus (thalamus)
Low-frequencysounds
Auditory cortex(temporal lobe) High-
frequencysounds
Thalamus
© 2012 Pearson Education, Inc.
Vision
Accessory Structures Eyelids Lacrimal apparatus
Eye Fibrous tunic Vascular tunic Neural tunic Chambers of the eye
Visual pathways
© 2012 Pearson Education, Inc.
Figure 18.19a Accessory Structures of the Eye, Part I
Superficial anatomy of the right eye and its accessory structures
Pupil
Corneallimbus
Lateralcanthus
Sclera
Eyelashes
Palpebra
Palpebralfissure
MedialcanthusLacrimalcaruncle
© 2012 Pearson Education, Inc.
Figure 18.19c Accessory Structures of the Eye, Part I
Diagrammatic representation of a deeper dissectionof the right eye showing its position within the orbitand its relationship to accessory structures,especially the lacrimal apparatus
Opening of nasolacrimal duct
Inferior nasalconcha
Nasolacrimal duct
Lacrimal sac
Inferior lacrimalcanaliculus
Medial canthus
Superior lacrimalcanaliculus
Lacrimal punctum
Tendon of superioroblique muscle
Inferioroblique muscle
Inferiorrectus muscle
Superiorrectus muscle
Lacrimalgland ducts
Lower eyelid
Lateral canthus
Lacrimal gland
© 2012 Pearson Education, Inc.
Figure 18.21ab Sectional Anatomy of the Eye
The three layers, ortunics, of the eye
Fibroustunic
(sclera)
Vasculartunic
(choroid)
Neuraltunic
(retina)
Major anatomical landmarks and featuresin a diagrammatic view of the left eye
Central retinalartery and vein
Optic nerve
Optic disc
Fovea
Retina
Choroid
Sclera
Posterior cavity(Vitreous chamber filledwith the vitreous body)
Ora serrata Fornix
Palpebral conjunctiva
Ocular conjunctiva
Ciliary body
Anterior chamber(filled with aqueoushumor)
Lens
Pupil
Cornea
Iris
Posterior chamber(filled with aqueoushumor)
Corneal limbus
Suspensoryligaments
© 2012 Pearson Education, Inc.
Figure 18.23a Retinal Organization
Histological organization of the retina. Note that thephotoreceptors are located closest to the choroid rather than near the vitreous chamber.
LIGHT
Amacrine cell
Horizontal cell Cone Rod Choroid
Pigmentedpart of retina
Rods andcones
Bipolar cells
Ganglion cells
Nuclei ofganglion cells
Nuclei of rodsand cones
Nuclei ofbipolar cells
The retina LM 70
© 2012 Pearson Education, Inc.
Figure 18.24
Pigmentedepithelium
Suspensoryligaments
Posteriorcavity
(vitreouschamber)
Lens
Ciliaryprocess
Choroid
Retina
Sclera
Conjunctiva
Ciliary body
Body of iris
Canal ofSchlemm
Posteriorchamber
Anteriorchamber
Anteriorcavity
Cornea
Pupil
© 2012 Pearson Education, Inc.
Figure 18.21d Sectional Anatomy of the Eye
Sagittal section through the eye
Ora serrata
Conjunctiva
Cornea
Lens
Anterior chamber
Iris
Posterior chamber
Suspensoryligaments
Ciliary body
Posteriorcavity
(vitreouschamber)
Duramater Retina Choroid Sclera
Optic nerve(N II)
© 2012 Pearson Education, Inc.
Figure 18.21e Sectional Anatomy of the Eye
Sagittal section through the eye
Orbital fatCentral arteryand vein
Medial rectusmuscle
Ethmoidallabyrinth
Optic nerve
Optic disc
Fovea
Ora serrata
Ciliary body
LensCiliaryprocesses
Medial canthus
Lacrimal caruncle
Lacrimal punctum
Nose
Anterior cavity
Posteriorchamber
Anteriorchamber
Edge ofpupil
Visualaxis
Cornea
Iris
Suspensory ligament of lens
Corneal limbus
Conjunctiva
Lower eyelid
Lateral canthus
Sclera
Choroid
Retina
Posterior cavity
Lateral rectus muscle
© 2012 Pearson Education, Inc.
Figure 18.26 Anatomy of the Visual Pathways, Part IILEFT SIDE RIGHT SIDE
Left eyeonly
Right eyeonly
Binocular vision
Optic nerve (N II)
Optic chiasm
Optic tractOther hypothalamicnuclei, pineal gland,
and reticularformation
Suprachiasmaticnucleus
Superiorcolliculus
Lateralgeniculatenucleus
Projectionfibers (opticradiation)
Lateralgeniculate
nucleus
RIGHT CEREBRALHEMISPHERE
LEFT CEREBRALHEMISPHERE
Visual cortex ofcerebral hemispheres