Download Ch15 Special Senses

CHAPTER 15 SPECIAL SENSES
senses
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general senses
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widely distributed
somatic senses - touch, temperature, muscle spindles
visceral senses - from organs
no specialized receptor
special senses
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specialized receptor structure
located only in head
cranial nerves to special centers in brain
special senses
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taste
smell
vision
hearing
equilibrium
Taste
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papillae
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bumps on tongue
fungiform
circumvallate
filiform
taste buds
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epithelia within papillae
gustatory cells
actual receptors
supporting cells
basal cells
gustatory pathway
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receptor
sensory nerves
medulla
thalamus
cortex
smell = olfaction
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olfactory epithelium
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olfactory receptor cells
– bipolar cells
– olfactory cilia
supporting and basal cells
superior nasal mucosa
receptors
olfactory pathway
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olfactory receptors
olfactory nerve (CN I)
pass through ???
olfactory bulb
olfactory tract
axons of mitral cells
brain centers
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limbic system
piriform lobe of cortex
(uncus)
EYE
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special sense for vision
photoreceptors
light, color
eye = organ to focus light on the receptors
specialized cerebral cortex
external eye
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eyelids
conjunctiva
lacrimal apparatus
extrinsic muscles
eyelid = palpebrae
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protect and lubricate
tarsal plates
levator palpebrae superioris
orbicularis oculi
medial and lateral canthus (commissure)
lacrimal caruncle
tarsal glands (Meibomian glands)
eyelashes
sensory
conjunctiva
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transparent membrane
palpebral conjunctiva
bulbar conjunctiva
conjunctivitis
lacrimal apparatus
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lacrimal gland
lacrimal punctum
canaliculus
lacrimal sac
nasolacrimal duct
extrinsic eye muscles
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superior rectus
CN III
inferior rectus
CN III
medial rectus
CN III
lateral rectus
CN VI
superior oblique
CN IV
inferior oblique
CN III
eyeball
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3 layers = tunics :
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fibrous
tunic
vascular tunic
sensory tunic
Fibrous tunic = dense reg. c.t
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sclera
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cornea
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“white of the eye”
support
muscle attachment
transparent
avascular
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limbus
– junction of sclera to cornea
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choroid
blood vessels
pigmented (melanin)
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ciliary process
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ciliary muscle
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ciliary zonule
vascular tunic
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ciliary body
produces aqueous humor
iris
smooth muscle controls size of pupil
• dilator pupillae
dilate pupil
• sphincter pupillae constrict pupil
pupillary light reflex
CN ???
lens
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transparent
avascular
focus light onto retina
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via ciliary muscles
cataracts
= cloudy lens
proteins degenerate
sensory tunic
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= retina
pigmented layer
neural layer
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photoreceptor cells
• rods
• cones
light
peripheral
color, acuity
central
bipolar cells
ganglion cells
axons = optic nerve
retina structures
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optic disc
optic nerve exit through retina
= blind spot
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macula lutea
center of retina
mostly cones
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fovea centralis
center of macula
only cones = focal spot
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ora serrata retinae
border with ciliary bodies
cavities (segments)
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divided by lens and suspensory ligt.
posterior cavity
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vitreous humor
holds retina in place
anterior cavity
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aqueous humor
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nutrients for lens and cornea
made by ciliary body
anterior cavity
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anterior chamber
anterior to iris
posterior chamber
posterior to iris
aqueous humor
nutrients for lens and cornea
made by ciliary body
scleral venous sinus
= canal of Schlemm
drains aqueous humor
• Glaucoma
visual pathway
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retina to occipital lobe :
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optic nerve
axons of ganglionic cells
through optic foramen
optic chiasm
cross of medial fibers of optic nerves
optic tract
in brain
thalamus
lateral geniculate nucleus
synapse with thalamic neurons
optic radiation
axons to occipital cortex
retina to other parts of brain :
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superior colliculi
reflex movt of eye muscles
pretectal nuclei
pupillary reflexes (CNII and III)
hypothalamus
sleep cycles
physics and sight
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myopia
nearsighted
eyeball too long
20 / >20
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hyperopia
far sighted
eyeball too short
20 / <20
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presbyopia
decreased near vision with age
weak ciliary muscles , lens
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astigmatism
varied shaped lens
EAR
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2 special senses (receptors) :
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hearing
equilibrium
3 parts :
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external ear
middle ear
inner ear
external ear
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auricle
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pinna
external auditory meatus
external auditory canal
tympanic membrane
eardrum
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• vibrates with sound waves
middle ear
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tympanic cavity
ossicles
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malleus
contacts tympanic membrane
incus
stapes
medial wall
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middle ear bones
increase vibration
contacts oval window
contacts inner ear
oval window
round window
(vestibular window)
(cochlear window)
pharyngotympanic tube
(= eustachian tube)
connects to nasopharynx
otitis media
inner ear
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2 receptors :
hearing
cochlea
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equilibrium
vestibule and semicircular canals
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bony labyrinth
cavity within temporal bone
filled with perilymph
inner ear
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cochlea
semicircular canals
vestibule
membranous labyrinth
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membranes within bony labyrinth
filled with endolymph
cochlear duct
within cochlea
semicircular ducts
within semicircular canals
utricle
within vestibule
saccule
within vestibule
cochlea
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cochlea
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cochlear duct
spiral cavity of bony labyrinth
spiral membranous labyrinth w/in cochlea
contains receptors = Organ of Corti
2 chambers next to cochlear duct :
scala vestibuli contacts oval window (vestibule)
scala tympani contact round window (cochlear)
Organ of Corti
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= spiral organ
receptor mechanism
hair cells
receptor cells
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stereocilia
contact tectorial membrane
basilar membrane
supporting cells
tectorial membrane
cochlear nerve
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spiral ganglia
VIII to brain
cell bodies
auditory pathway
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to temporal lobe
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cochlear nerve
cochlear nuclei
thalamus –
temporal lobe
to inferior colliculi
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auditory reflex
to cerebellum
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olivary nuclei
equilibrium
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2 structures :
vestibule
static equilibrium (vs gravity)
linear acceleration
semicircular canals
dynamic equilibrium
rotational acceleration
Vestibule
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2 structures of membranous labyrinth :
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utricle
horizontal motions
saccule
vertical motion
macula
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sensory epithelium
supporting cells
hair cells
receptor cells
otolithic membrane
• otoliths
calcium crystals
head or spacial movement tilts the otoliths and bend
vestibular nerve
the hair cells
semicircular canals
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3 planes of space
ampulla
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base of each duct
crista ampullaris
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cells within ampulla
supporting cells
hair cells
receptor cells
cupula
gel covering hair cells
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rotation of head moves the cupola and bends the hair cells
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vestibular nerve
equilibrium pathway
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vestibular nerve
vestibular nuclei
medulla
cerebellum
reflex movement
cerebrum
parietal lobe
conscious awareness of position and movement