CHEMICAL SENSES
Smell: olfactory epithelium
1. Location roof of nasal cavity olfactory receptors;
pseudostratified epithelium
2. Supporting cells columnar epithelium; secrete mucus;
aromatic chemicals dissolved
3. Basal cells small cells at base of epithelium; become
receptor every 50 days
4. Olfactory receptor bipolar neurons; unmyelinated axons
in fasicles through cribiform
5. Olfactory hairs (cilia) dendrite of the olfactory
receptor; receptive surface; ↑area
6. Specificity thousand different receptor protein;
binding combinations; 10,000 odors
Smell: physiology
1. Smell transduction chemical sense like taste
-a. Olfactory hair chemical binds to G-protein associated
olfactory receptor protein
-b. G protein activates adenylate cyclase
-c. Adenylate cyclase cAMP from ATP
-d. cAMP opens Na channels
-e. Na influx depolarization and nerve impulse generation
2, Olfactory pathway CNS
-a. Olfactory nerve (CN I) axons coming from olfactory receptor
-b. Olfactory bulb distal end of the olfactory tract
-c. Mitral cells cells of the second order sensory neuron
found in the olfactory bulb
-d. Glomeruli first second order neurons synapse; each for
different types of odors
-e. Olfactory tract contains the axons of the second order
neurons
-f. Olfactory cortex via the thalamus; smells are
consciously interpreted
-g. Subcortical structures hypothalamus, amygdala, other
limbic system; emotional
Smell: homeostatic imbalances
1. Anosmias inability to smell; olfactory nerve tear; nose
inflammation; zinc deficiency
2. Uncinate fits olfactory hallucinations; unpleasant
odors; epileptics before seizure
Taste: taste buds
1. Tongue most; some also found on soft palate, cheeks,
pharynx, and epiglottis
2. Papillae peg like projections; rough appearance; most
taste bud found here
-a. Filiform pointed thread like structures; most do not
contain taste buds
-b. Fungiform over most of tongue but mostly tip and along
the sides
-c. Circumvallate rounded; largest, least numerous; 7 to
12; inverted V back of tongue
3. Taste bud structure as follows
-a. Supporting cells form the bulk of taste bud; insulate
receptor cells from each other
-b. Receptor cells gourd shaped; long microvilli (gustatory
hairs); taste pore to surface
-c. Basal cells stem cells become supporting which become
gustatory; every 15 days 2. 4. Basic
taste sensation basic qualities
-a. Sour this is the taste of acids; hydrogen ions
-b. Sweet sugar; also some amino acids
-c. Bitter alkaloids, toxins, rotten food
-d. Salty inorganic salts; sodium chloride being the most
stimulating
-e. Umami amino acid glutamate; beef taste and aged
cheese; MSG
5. Locations not as localized as led to believe
-a. Anterior tongue sensitive to sweet and salty
substances
-b. Posterior tongue sensitive to bitter substances
-c. Lateral tongue sensitive to sour substances
Taste: physiology
1. Saliva chemical must be dissolved before it can be
tasted
2. Gustatory hairs chemical comes in contact with this
3. Synaptic vesicles in gustatory cells; generator
potential in associated neurons
4. Taste transduction chemical to nerve impulse
-a. Ion channels for salty (Na+ ) and sour (H+)
-b. G protein linked for bitter and sweet
5. Cranial nerves include
-a. Facial nerve (CN VII) transmits data from the anterior
two thirds of tongue
-b. Glossopharyngeal nerve (CN IX) transmits data from
posterior third of tongue
-c. Vagus nerve (CNX) transmits taste data from epiglottis
and pharynx
6. Central nervous system include
-a. Solitary nucleus medulla; synapse with afferent fibers
of cranial nerves
-b. Thalamus cell bodies receive inputs from the solitary
nucleus
-c. Gustatory cortex relayed from the thalamus; located in
the parietal lobe
-d. Limbic system fibers to the hypothalamus, other limbic
system; appreciation of food
-e. Parasympathetic reflexes solitary nucleus start
reflexes salivation, gastric juices
7. Other influences on taste
-a. Smell about 80% of our appreciation of what we are
eating
-b. Other receptors thermoreceptors, mechanoreceptors,
nociceptors
EYE AND VISION
Eye: accessory structures
1. Eyebrows coarse short hairs; shade; prevent
perspiration going into eyes
2. Palpebrae eyelids
-a. Palpebral fissure eyelids meet; eyelid slit
-b. Commissures (canthi) medial and lateral angles of the
eye
-c. Caruncle elevation medial canthus; sebaceous, sweat
glands; oily secretion; sandman
-d. Tarsal plates flat connective tissue sheets which
support the skin of the eyelids
-e. Eyelashes margins of eyelids; hair follicles with root
hair plexus; very sensitive
-f. Meibonian (tarsal) gland in tarsal plate; modified
sebaceous glands, lubrication
-g. Ciliary glands modified sweat glands which lie between
hair follicles
3. Conjunctiva a transparent mucus membrane; lines the
anterior eye and inner eyelids
-a. Palpebral conjunctiva part of the conjunctiva which
lines the inner eyelid
-b. Bulbar (ocular) conjunctiva lines the anterior; only
white, not cornea
-c. Conjunctival sac space between palpebral, bulbar
conjunctiva when eyes are closed
4. Lacrimal apparatus include
-a. Lacrimal gland in orbit above lateral eye; lacrimal
secretions always produced; blink
-b. Lacrimal canal paired; medial canthus excess
secretions leave the surface of the eye
-c. Lacrimal sac tears drain into this form the lacrimal
canals
-d. Nasolacrimal duct from lacrimal sac to this duct; into
the nasal cavity
-e. Lacrimal secretions clean, lubricate, moisten,
protect; mucus, antibodies, lysozyme
Eye: extrinsic eye muscles
1. Extrinsic eye muscles insert outer surface of the
eyeball; move, help maintain shape
2. Rectus muscles common ligament from posterior orbit;
locations, actions same
-a. Medial rectus moves eye medially
-b. Superior rectus moves eye superiorly
-c. Lateral rectus moves eye laterally
-d. Inferior rectus moves eye inferiorly
3. Oblique muscles move eye in vertical plane when it is
already turned medially
-a. Superior oblique common origin rectus; medial to
trochlea; down and lateral
-b. Trochlea fibrocartilagenous loop
-c. Inferior oblique medial orbit to inferiolateral eye;
upward and laterally
4. Neural control cranial nerves
-a. Oculomotor nerve (CN III) all except the lateral
rectus and the superior oblique
-b. Trochlear nerve (CN IV) innervates the superior
oblique; trochlea
-c. Abducens nerve (CN VI) innervates the lateral rectus
Eye: tunics
1. Fibrous tunic outermost tough, avascular connective
tissue
2. Vascular tunic (uvea) middle layer
3. Sensory tunic retina
Eye: fibrous tunic
1. Sclera posterior, most; white, opaque; posteriorly
continuous with dura mater
2. Cornea anterior sixth; transparent, regular arrangement
of collagen
-a. Anterior surface stratified squamous; merges with
bulbar conjunctiva (protection)
-b. Posterior surface simple squamous epithelium; actively
pump Na, water; for clarity
Eye: vascular tunic (uvea)
1. Choroid brown pigmented posterior 5/6th
-a. Vascular supply other eye tunics
-b. Brown pigment prevents light from scattering
2. Ciliary body anterior uvea; a thickened ring of tissue
which encircles the lens
-a. Ciliary muscles smooth muscle fibers; bulk ciliary
body; control shape of lens
-b. Ciliary processes near lens ciliary body fold;
capillaries; anterior segment fluid
-c. Suspensory ligaments from ciliary body to lens; halo
of fibers which suspend lens
3. Iris visible colored anterior uvea; circular, radial
smooth muscle; size of the pupil
-a. Pupil opening in iris controls light; autonomic
nervous system control
Eye: sensory tunic (retina)
1. Pigmented layer outermost, single celled; abuts
choroid; covers ciliary body, iris
-a. Function absorbs light; prevents scattering
2. Neural layer layer responsible for transduction and
transmission of the visual signal
3. Retinal cells include
-a. Ganglionic cells innermost cells; generate action
potentials; axons form optic nerve
-b. Bipolar cells receive local currents from
photoreceptors; transmit to ganglion cells
-c. Photoreceptors outermost; rods dim light, peripheral;
cones bright light acuity color
4. Macula lutea oval, mostly cones; inner layers
displaced, less obstructed; visual acuity
-a. Fovea centralis minute pit in the macula lutea; only
cones; greatest visual acuity
5. Optic disc optic nerve leaves the eye
-a. Blind spot at optic disc, no photoreceptors; visual
filling in compensates for this
6. Fundus posterior wall of the eye; retinal seen with
ophthalmoscope
7. Blood supply - outer 1/3rd from choroid; inner
2/3rd central artery, vein; optic nerve
Eye: internal chambers and fluids
1. Posterior segment chamber which is posterior to the
lens and suspensory ligament
-a. Vitreous humor clear gel; collagen fibers; viscous
ground substance; eye shape
2. Anterior segment anterior to lens and suspensory
ligaments
-a. Anterior chamber part of anterior segment between
cornea and iris
-b. Posterior chamber part of anterior segment between
iris and posterior segment
-c. Aqueous humor forms, drains constant rate; nutrients,
O2 for lens and cornea
-d. Ciliary body capillaries produce the aqueous humor
-e. Circulation posterior chamber freely diffuses
anteriorly
-f. Scleral venous sinus (
-g. Glaucoma drainage is blocked, intraocular pressure,
optic nerve, retina compressed
Eye: lens
1. Lens biconcave flexible structure; shape can change;
for focusing of light
2. Lens epithelium anterior layer of cuboidal cells;
differentiate into lens fibers
3. Lens fibers packed tightly; layers of onion; most of
lens; no nuclei, few organelles
4. Crystallins protein; structure cause transparency;
enzymatically energy from sugar
5. Aging new lens fibers continuously added; thickness of
lens increases throughout life
6. Cataracts less nutrients to deeper fibers clumping of
proteins; clouding; sunlight
Vision: light and optics
1. Wavelength color; EM radiation short wavelength gamma
to long wave radio waves
2. Visible light small part of the spectrum
3. Cones respond to different wave lengths (blue, green,
and red; there is some overlap
4. Refraction light passes to mediums of different
densities it bends
5. Lens curved transparent material which is curved; light
hitting will be refracted
-a. Convex lenses more convex more light will be bent,
focal point closer to the lens
Vision: focusing
1. Refraction lens and cornea mostly; vitreous and aqueous
humors some
2. Distant vision our eyes best adapted for this; more
than 6 m away; natural condition
-a. Cornea responsible for most refraction of light from
distant objects; parallel lines
-b. Ciliary muscles are relaxed
-c. Suspensory ligaments are taut
-d. Lens is pulled by suspensory ligaments; is at its
thinnest at its least convex
3. Close vision closer than 6 m diverge as the approach
the eye; diverging light
4. Accommodation increase lens thickness; more convex;
focal point closer to lens
-a. Ciliary muscles pull ciliary body anteriorly; releases
tension suspensory ligaments
-b. Lens no longer held taut, recoils; bulges, increasing
thickness, refractory power
5. Pupils prevents most divergent light from entering the
eyes; decreases blurring
6. Convergence medial rotation of both eyes; both are
focused on the same object
7. Homeostatic imbalances include
-a. Myopia nearsightedness; distant objects focused before
retina; concave lenses
-b. Hyperopia farsightedness; near objects focused behind
retina; convex lenses
-c. Astigmatism uneven curvature of lens leads to
blurring; special cylindrical lenses
Vision: functional anatomy of photoreceptors
1. Outer segment receptor part found mostly in pigmented
layer; shape rod, cone
-a. Disc infoldings of plasma membrane; pigments
responsible for vision; ↑surface area
-b. Renewal disc renewed daily (circadian) rhythm;
phagocytes in pigmented layer
-c. Stalk connects inner to outer segments
2. Inner segment connects to cell body directly in cones
and by an outer fiber in rods
3. Inner fiber from cell body to synaptic ending
Vision: chemistry of visual pigments
1. Retinal from vitamin A; light absorbing molecule;
change 3-D shapes (isomers)
-a. 11-cis isomer bent or kinked shape when attached to
opsin
-b. all-trans isomer after being struck by light straight
shape and detaches from opsin
2. Opsin the protein attached to retinal; four varieties
(one rod and three cones)
Vision: stimulation of photoreceptors
1. Rods black and white
-a. Rhodopsin the photopigment of rods (retinal and opsin)
-b. Light reaction break down of rhodopsin &
isomerazation of retinal; bleaching
-c. Dark reaction all-trans to pigmented layer; ATP back
to 11-cis; transported back
2. Cones color vision
-a. Opsin 3 different types; require high degree of light,
various wavelengths
-b. Retinal isomerazation, detachment from opsin
essentially same as rods
3. Color blindness congenital lack of one or more cone
types; usually a sex linked
Vision: light transduction in photoreceptors
1. Dark reaction
-a. Cyclic GMP binds to sodium channel and causes it to
remain open
-b. Transmembrane potential open sodium channels keep this
at 40 mV (depolarized)
-c. Neurotransmitters continuous release
2. Light reaction
-a. Free opsin activates a G protein subunit called
transducin
-b. Transducin activates phosphodiesterase
-c. Phosphodiesterase converts cGMP to GMP; no longer
bound to sodium channel
-d. Sodium channels no longer attached by cGMP close and
sodium influx stops
-e. Hyperpolerization membrane potential of 70 mV;
efflux of potassium still occurring
-f. Neurotransmitters is inhibited
g. Graded potentials no action potential of retinal cell;
only ganglion cells do this
Vision: light and dark adaptation
1. Light adaptation bleaching rhodopsin rods;
nonfunctioning; cones take over; 10 min
2. Dark adaptation cones dont function low light; dark rhodopsin accumulates 30 min
3. Nyctalopia (night blindness) rod functioning impaired
usually vitamin A deficiency
Vision: visual pathway
1. Optic nerve (CN II) convergence axons from the retinal
ganglion cells
2. Optic chiasma the fibers from medial eye cross over to the opposite side
3. Optic tracts sends these mixed up tracts to the
thalamus
4. Lateral geniculate body of thalamus, receives most of
the fibers from the optic tract
5. Optic radiations cerebral white matter (axons from
thalamus); to
6. Primary visual cortex occipital lobe; conscious
perception of visual image
7. Other connections include
-a. Superior colliculi extrinsic eye muscles; visual
reflex
-b. Pretectal nucleus midbrain; pupillary response
-c. Suprachiasmatic nucleus hypothalamus; biological
rhythms
Vision: stereoscopic vision
1. Stereoscopic vision same image seen from different
angles; eyes face anteriorly
2. Depth perception locate objects 3D space; cortical
fusing of slightly different images
Vision: retinal processing
1. Retinal processing in the retina itself
3. Photoreceptor no longer release inhibitory
neurotransmitter
4. Bipolar cells depolarizing excite the ganglion cells;
hyperpolarizing inhibit them
-a. Cones bipolar cells from cones directly to ganglion
cell
-b. Rods bipolar cells from cones to amacrine cells via
gap junctions
5. Amacrine cells input from rods; summation detour rod
output; smeary picture
6. Horizontal cells gap junctions; bipolar cells from
rods; ↑light/dark contrast
Vision: other levels of processing
1. Thalamic processing receives input from both eyes
-a. Lateral geniculate nucleus movement, depth perception,
sharpen contrast
-b. High visual color vision concerned with input from
high acuity areas of the retina
2. Cortical processing two areas concerned with visual
perception
-a. Primary visual (striate) cortex forms topographical
map of the retina; info to the
-b. Prestriate cortices visual assoc. areas; dynamic
images; form, color, depth, motion
THE EAR: HEARING AND BALANCE
Ear anatomy: outer (external) ear
1. Auricle (pinna) elastic cartilage; surrounds opening of
external auditory canal
2. External auditory canal (meatus) to the tympanic
membrane; hair, sebaceous glands
3. Ceruminous glands produce cerumen; modified apocrine
sweat glands; debris, insect
4. Tympanic membrane connective tissue membrane; outer
covered skin; inner, mucosa
Ear anatomy: middle ear (tympanic cavity)
1. Oval window opening in the lateral wall of the middle
ear; leads to vestibule
2. Round window inferior to oval window; covered by
secondary tympanic membrane
3. Mastoid antrum canal posterior wall communication with
air cells in mastoid process
4. Pharyngotympanic tube to nasopharynx; epithelium
continuous: equalize pressure
5. Ossicles articulate by synovial joints; vibration
tympanic membrane to oval window
-a. Malleus (hammer) handle of malleus secured to tympanic
membrane
-b. Incus (anvil) articulates with the malleus laterally
and the stapes medially
-c. Stapes (stirrup) secured by an annular ligament it
fits in the oval window
6. Tensor tympani wall of the auditory tube; inserts into
the malleus; protect loud noise
7. Stapedius muscle medial wall to stapes; protects
against loud noise; limits vibration
Ear anatomy: inner (internal) ear (labyrinth)
1. Bony (osseous) labyrinth in temporal; vestibule,
cochlea, and the semicircular canals
2. Membranous labyrinth membranous sacs and ducts which
follow the bony labyrinth
3. Fluids conduct sound vibration; respond to changes in
body position and acceleration
-a. Perilymph fills bony labyrinth; like cerebrospinal
fluid; membranous labyrinth floats
-b. Endolymph in the membranous labyrinth; like potassium
rich intracellular fluid
4. Vestibule central egg shaped; posterior to cochlea,
anterior to semicircular canals
-a. Saccule smaller membranous sac; closer to cochlea
-b. Utricle larger sac; closer to the semicircular canals
-c. Maculae equilibrium receptors in saccule, utricle;
respond to gravity, head position
5. Semicircular canals more posterior; orientated in 3
planes; anterior, posterior, lateral
-a. Semicircular ducts each semicircular canal has a
semicircular duct
-b. Ampulla enlarged swelling base of each semicircular
duct; has the crista ampullaris
-c. Crista ampullaris equilibrium receptors; respond to
angular movement of the head
6. Cochleae spiral bony cavity; size of a split pea; from
vestibule; makes 2 ½ turns
-a. Modiolus bony column around which the cochlea coils
-b. Cochlear duct membranous labyrinth through cochlea; spiraling wedge shape worm
-c. Organ of Corti housed in the cochlear duct; is the
receptor organ for hearing
-d. Scales cochlear duct, extensions of modiolus; separate
cochlea into 3 chambers
-e. Scala vestibuli superior to cochlear duct; abuts oval window; contains perilymph
-f. Scala media the cochlear duct; contains endolymph
-g. Scala tympani inferior to cochlear duct; terminates
round window; has perilymph
-h. Helicotrema region of cochlear apex where scala
vestibuli and scala tympani meet
-i. Vestibular membrane between scala media, scala
vestibuli; secretes endolymph
-j. Basilar membrane supports organ of Corti; between scala media and scala tympani
-k. Tectorial membrane in spiral organ; tweaks hair cells
Hearing: properties of sound
1. Sound pressure disturbance from a vibrating object;
displaces air molecules
-a. Sine Wave air pressure vs time; vibrating object
causes this change in pressure
2. Wavelength the distance between two different crest
3. Frequency the number of crest in a given amount of time
4. Hertz (Hz) waves per second; greater the frequency the
less the wavelengths
-a. Range of human ear about 20 to 20,000 Hz
5. Amplitude height of the wave; represents the intensity
of the sound
6. Decibels measure of sound intensity; is logarithmic; 20
is 10 time greater than 10
Hearing: transmission of sound
1. Tympanic membrane sound causes it to vibrate at same
frequency
2. Ossicles energy from tympanic membrane transferred by
these to the oval window
3. Amplification former much larger than latter, pressure
hitting oval window 20 times
4. Oval window vibration, perilymph in scala vestibuli
back &forth at same frequency
5. Round window perilymph in scala tympani pushes
membrane; pressure release
6. Vestibular membrane its vibration transmitted to
endolymph inside cochlear canal
7. Endolymph its vibration causes the basilar membrane to
vibrate
8. Basilar membrane resonate at the frequency of the
endolymph
-a. Fibers of the basilar membrane vibrate; regions
vibrate at different frequencies
-b. High frequencies closest to oval window; short, stiff
fibers
-c. Low frequencies near apex; long, floppy
-d. Differential stimulation different areas stimulate
different hair cells; different pitches
Hearing: hair cell excitation
1. Organ of Corti atop basilar membrane; 16,000 hearing
cells called cochlear hair cells
2. Cochlear hair cells located between the basilar and the
tectorial membrane
3. Inner hair cells single row; almost entirely
responsible for sending the auditory signal
4. Outer hair cells 3 rows; maybe for amplification speed
basilar membrane movement
-a. Efferent fibers cause outer hair cells to vibrate;
spontaneous otoacoustic emissions
5. Stereocilia cilia of hair cells into endolymph; tallest
cilia embedded in tectorial
-a. Tip-links fibers that link the stereocila together
6. Tectorial membrane moves in response to basilar
membrane; tweaks the stereocilia
7. Transduction bending cilia toward embedded cilia
stiffens tip-links; mechanic opens
-a. Cation channels influx K (and Ca); graded
depolarization; neurotransmitter release
8. Cochlear nerve branches are coiled about the base of
the hair cell; depolarize
9. Intensity any audible sound will result in action
potential; intensity is result AP rate
Hearing: auditory pathways
1. Spiral ganglion sensory ganglion of cochlear nerve;
cell bodies of afferent neurons
-a. Bipolar type of sensory neurons
2. Cochlear nerve part of the vestibulocochlear nerve (CN
VIII); to cochlear nucleus
3. Cochlear nucleus in the medulla; sends fibers to the
superior olivary nucleus
4. Superior olivary nucleus sends impulses to inferior
colliculus
-a. Lateral lemniscal tract the tract uses for this
5. Inferior colliculus auditory reflex center of the
brain; axons sent to thalamus
6. Medial geniculate body in the thalamus; sends axons to
the auditory cortex
7. Auditory cortex some fibers decussate; each auditory
cortex, impulses from both ears
Hearing: auditory processing
1. Pitch cochlear nucleus, auditory cortex have tonotopic
maps
2. Loudness for a frequency, intensity cause more impulses
sent that part of cortex
3. Localization superior olivary nucleus; 2 cues; relative
intensity and timing; both ears
Hearing: homeostatic imbalances
1. Conduction deafness interference conduction of
vibrations to fluid of inner ear
-a. Causes blockage of external ear; otosclerosis
(ossicles fuse); tympanic perforated
2. Sensorineural deafness damage hair cells, neural
component (hair cells to cortex)
-a. Causes - over exposure to loud noises
3. Tinnitus ringing or clicking sounds in the ear
-a. Causes cochlear nerve degeneration, inflammation
middle, inner ear, medications
4. Menieres syndrome labyrinth disorder; both cochlea and
semicircular canals
-a. Symptoms vertigo, tinnitus, and ultimate loss of
hearing
-b. Causes excessive endolymph or mixing of endolymph and
perilymph
Static equilibrium: maculae
1. Static equilibrium head position for posture and
balance
2. Maculae each macula is a flat epithelial patch; static
and dynamic
3. Supporting cells the most numerous type of cells found
in the maculae
4. Hair cells receptor cells respond to the displacement
of the head; two types of hairs
-a. Stereocilia has many elongated microvilli
-b. Kinocilium have one long, true cilia protruding from
its apical end
5. Otolithic membrane flattened jelly like mass; hairs of
the hair cells are embedded
-a. Otoliths calcium carbonate crystals; otolithic
membrane; give weight to membrane
6. Utricle maculae horizontal; hair cells vertical;
horizontal placement or movements
7. Saccule maculae vertical; hair cells horizontally;
vertical placement or movements
8. Vestibular nerve endings at the base of each hair cell
10. Vestibular ganglia cell bodies of the vestibular
nerves; vestibulocochlear nerve
11. Transduction gravity and linear acceleration stimuli
-a. Neurotransmitters are constantly release
-b. Linear movements otolithic membrane to move;
-c. Otolithic membrane movement causes increase or
decrease neurotransmitters
-d. Depolarization stereocilia bent toward kinocilium;
↑neurotransmitter
-e. Hyperpolarization stereocila bent away from
kinocilium; ↓neurotransmitter
-f. Brain both the decrease and increase in the rate of
impulses is detected
Dynamic equilibrium
1. Dynamic equilibrium during movement
2. Macula for linear acceleration; horizontal or vertical
plane
3. Crista ampullaris for rotational acceleration
Crista ampullaris
1. Supporting cells again more numerous that hair cells
2. Hair cells the receptor cells; have stereocilia and one
kinocilium
3. Cupula gel like mass found at the base of each
semicircular duct (crista ampullaris)
4. Vestibular nerve fibers dendrites encircle the base of
each hair cell
5. Transduction the result of rotational signal
-a. Endolymph head one direction endolymph opposite
direction; movement of cupula
-b. Hair cells move; results in
-c. Depolarization hairs bent in one direction; impulses
reach brain at faster rate
-d. Hyperpolarization hairs bent in other direction;
impulses reach brain at slower rate
5. Equilibrium pathway to the brain
-a. Vestibular nuclear complex form vestibular, visual,
somatic receptors; cerebellum
-b. Cerebellum also receives input from all of above;
output to above