Download Special Senses

A. The complex sensory receptors are
within large complex sensory organs in
the head
1. Smell--------------Olfactory organs
2. Taste---------------Taste buds
3. Hearing------------Cochlea
4. Equilibrium-------vestibule &
semicircular canals
5. Sight----------------Retina of eyes
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1.Vision receptors are
photoreceptors
(rods and cones)
located in the retina
of the eye at right
See layers of Retina:
Axons of ganglia become Optic Nerve to visual cortex
of occipital lobe
Ganglion cells
Bipolar cells
Rods and cones (photo receptors)
Pigmented Epithelial
Choroid layer (not retina) bllod rich
Sclera (not retina) fibrous tunic dense connective (f)
2. Parts of eye
2
Parts of eye
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Lets look for:
sclera/cornea
Palpabrae
lacrimal gland, sac
Caruncle
nasolacrimal duct
Conjunctiva (f)
tarsal & cilary glands (f)
Fluid location
optic disc & fovea cent
Ciliary processes (f) & muscles lens
Suspensory ligament
Iris w/ radial & circular muscles
3. Lateral paths do not
cross, but medial
paths do cross at the
optical chiasm
(1)Conjunctiva (mucous
membrane)
(2)The muscles that
move the eye
(a)superior, inferior,
lateral, and medial
recti, and superior &
inferior oblique
(3)Lacrimal gland and
ducts
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(2) Extrinsic Eye muscles
(1) Accommodation,
changes in lens, is
accomplished by
cilliary muscles and
suspensory ligaments
(locate on model).
6. Tunics of the eye
a. The outermost tunic is fibrous tunic,
cornea and sclera.
b. The middle vascular tunic is the uvea.
(1) layer 1, choroid
(2) layer 2, ciliary body
(3) layer 3, iris = opening
which regulates amount
light allowed into eye
c. Sensory tunic 2 layered
retina (1) pigmented epi
(2) neural layer
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7. Other parts of eye
a.The fovea centralis
of the retina
provides acute
vision; cones are
concentrated here.
b.Optic disc, thru
which nerve fibers
leave the eye is a
blind spot, no rods
or cones.
(1)Aqueous humor
is fluid in
anterior eye.
(2)Vitreous humor
is fluid in
posterior eye.
1. Visual acuity (sharpness) Test
2. Color Blindness 3 types
3. Binocular Vision see 3 dimensions in
one direction w/ depth perception.
4. Eye reflexesa. photopupilary
b. accomodation pupillary
c. convergence
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Look for:
Sclera and cornea
Optic nerve
Lens, pupil, iris
Retina (reflective)
Inner layer of
ganglionic axons
attached to
optic disc
1 Ear has three parts, outer,
middle & inner
2. The outer ear’s auricle
funnels sound waves to
tympanic M/B, which
vibrates the lever system
of ossicles (malleus,
incus, stapes)
transmitting vibration to
oval then round window
3. Vibration reaches
cochlea, causing
endolymph inside
cochlear duct to vibrate
basilar M/B & dendritic
ends of hair receptors
called stereocilia
.
4. Pharyngotympanic (auditory) tube equalizes
pressure between middle ear and external air
so eardrum works properly
5. Round window bulges outward into middle
ear to relieve pressure created by
compression of perilymph in scala tympani
from vibration
6. Bony labyrinth of inner ear has 3 divisions,
cochlea, vestibule, semicircular canals.
Within the cochlea is the membranous
labyrinth, the cochlear duct.
7. Presbycusis results from deterioration of
organ of corti can’t hear high sounds(aging
is cause)
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Cochlea (see fluid flow)
Cochlear histology
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Carefully look through
otoscope at partner’s ear
See page 280
a. Scala Vestibuli (top) and Scala Tympani (bottom)
chambers of bony labyrinth filled w/ perilymph
b. Scala media is middle portion (membranous labyrinth),
cochlear duct, filled w/ endolymph. Organ of corti
bottom right
c. Gelatinous Tectonic M/B thru which hair cells project
d. Basilar M/B forms floor of cochlear duct
c. Axons of outer and inner hair cells (auditory
receptors are stereocilia, or hairs ) SEE MODEL
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e. Resonance of basilar
membrane from high
(left end) to lower
sounds as go right
toward apex of cochlea
f. Length of basilar fibers
change from short
(high sounds) to
longer (lower sounds)
g. Hair Cells depolarize
leading to cochlear
nerve then to auditory
centers of temporal
lobe cortex.
Hearing tests (Audiometery)(write up for
lab report due 1 week after practical)
using format at start of lab text.
Weber/Rhine tuning fork test.
1. Question: Does sound remain
centralized (normal) or lateralize to one
side indicating _____?
2. Comparision of bone conduction and
air conduction of sound waves pg. 283
1. 3 semicircular canals
of inner ear are at
right angles to each
other
2. Each canal ends in an
ampulla (houses
crista ampullaris
filled with clusters
of sensory hair
cells, which
protrudes into a
gelatinous cupula)
wh/ communicates
w/ utricle.
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3. When rate of rotation changes, inertia
prevents endolymph from moving w/ head.
Fluid presses against cupula bending hair
cells in opposite direction. Bending
increases frequency of action potentials as
rotation accelerates.
1. Vestibule, composed of
utricle and saccule, is a
bony labyrinth b/w
semicircular canals and
cochlea
2. Hair cells of Vestibule’s
macula densa are
sensory receptors
3. Membranous labyrinth
suspended inside bony
labyrinth by perilymph.
ML is filled w/
endolymph.
1. Specialized pseudostratified ciliated epithelial cells are
located high in roof of nasal cavity.
2. Olfactory receptor cells are bipolar neurons whose
olfactory cilia extend outward from epithelium.
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3. Axons of bipolar cells reach thru the
cribiform plate of the ethmoid bone and
proceed as olfactory nerves, synapsing in
olfactory bulbs.
4. From there nerve impulses of olfactory bulbs
are conveyed to olfactory cortex uncus, w/o
synapsing in thalamus.
1.Receptors are gustatory
hairs extending thru
taste pore
2.Three types of papilla
are shown taste buds
on sides of
circumvallate&
fungiform
3. Afferent fibers become
VII, IX or X cranial and
lead to gustatory cortex
of postcentral gyrus
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