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Olfactorybulb
Olfaction
ChemoreceptorsPhotoreceptors
Vision
Mechanoreceptors
Audition
Sensory Transduction
Direction of light
Direction of retinal visual processing
Frontofretina
Fibers ofthe opticnerve
Ganglioncell
Amacrinecell
Bipolarcell
Cone Rod
Photoreceptorcells
Horizontalcell
Pigment layer
Choroid layer
Sclera
Backofretina
Anatomy of the Retina
Back of retina
Outersegment
Outersegment
Innersegment
Synapticterminal
Synapticterminal
Innersegment
Directionof
light
Cells ofpigment layer
Cone Rod
Discs
Mitochondria
Nuclei
Dendritesof bipolar
cells
Frontof retina
Phototransduction
Disc
Lightabsorption
Enzymes
Opsin
Retinene
Rhodopsin in the dark:retinene in 11-cis form
(inactive)
Rhodopsin in the light:retinene changes shape
to all-trans form(active)
all-trans formof retinene
11-cis formof retinene
Activation of photopigment
Activation of transducin (G protein)Activates PDE
Decrease in cyclic GMP
Closure of Na+ channelsin outer segment
Membrane hyperpolarization(the receptor potential)
Takesplacein outersegment
(Absorption)
(Reaction cascade)
(Spreads to synaptic terminal)
Takesplacein synapticterminal
Takesplace
in retina
(Removal of inhibition)
(If of sufficient magnitude to bring ganglion cell to threshold)
Closure of Ca2+ channelsin synaptic terminal
Release of inhibitory transmitter
Bipolar cells disinhibited (or, in effect, excited)
Graded potential changein bipolar cell
Action potential in ganglion cell
Propagation of AP to visual cortex (occipital lobe)visual perception
LIGHT
High concentrationof cyclic GMP
Na+ channels openin outer segment
Membrane depolarization
Opens Ca2+ channelsin synaptic terminal
Release of inhibitorytransmitter
(inhibition)
Bipolar cells inhibited
No action potentialin cell ganglion cell
No action potentialpropagation tovisual cortex
Takes placeinretina
(Spreads to synaptic terminal)
Takes place
inouter
segment
Takesplace
insynapticterminal
DARK
Outersegment
Innersegment
Synapticterminal
Cells ofpigment layer
Cone Rod
Discs
Nuclei
Bipolardendrites
Front of retina
Rods versus Cones
Properties of Rod and Cone Vision
RODS CONES
100 M per retina 3 M per retina
Vision in shades of gray Color Vision
High Sensitivity Low Sensitivity
Low Acuity High Acuity
Night vision Day vision
Much convergence in retina Little convergence in retina
More numerous peripherally Concentrated in fovea
What about adaptation?
Color Vision
Anatomy of the Auditory System
The Middle Ear and
Cochlea
APEX: Wider, more flexible end of basilar membrane (vibrates best with low-freq)
BASE: Narrower, stiffer end of BM near oval window (vibrates best with hi-freq)
The Traveling Wave
QuickTime™ and aCinepak decompressor
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Outerhair cells
(Stereocilia)
Tectorial membrane
Inner hair cells
Nerve fibers
Supporting cell
Basilar membrane
The Organ of Corti
The Hair Cell Potential
Tympanic Membrane Vibrates
Ossicles Vibrate
Oval Window Vibrates
Fluid Movement within Cochlea
Basilar Membrane Vibrates
Takesplace
in ear
Closure of Ca2+ channelsin synaptic terminal
Graded potential changein hair cell
Action potentials generated in auditory nerve
Propagation of AP to auditory cortex (temporal lobe)
sound perception
SOUND WAVES
Hair cell stereocilia bend as the movement of the basilar membrane displaces them in relation to the overlying tectorial membrane in which they are embedded.
Graded potential changein bipolar cell
Vibration ofround window
Energy dissipates (no sound perception)
The Transduction Channel
What about Adaptation?
What about the Outer Hair Cells?
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decompressorare needed to see this picture.
What about the Outer Hair Cells?
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Cochlear Implants