Transcript 6:7 Special Senses

Turn to Chapter 8: Special Senses
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“I See What Doesn’t Belong”
Ambiguous Illusions
Is this a rabbit
or a duck?
This man looks like your
average Joe right?
But what else is he?
Special Senses
Objectives
3.7 Analyze (explain) sensory perceptions.
3.8 Analyze (explain) diseases as related to
eachsystem
Seeing
Hearing
Smelling
Special Senses
• Special senses allow body to react to
the environment
• Body able to see, hear, taste, smell, and to
maintain balance
• Senses occur because the body has
structures that receive sensation, nerves
carry message to brain, and brain
interprets and responds to message
The Eye and Vision
• Sense of sight
• Light rays transmitted to the optic nerve
• Optic nerve relays information to brain
for interpretation
• Eye is well protected by:
– Bony socket
– Eyelids and eyelashes
– Lacrimal glands– tears empty into nasal cavity
– Conjunctiva– thin membrane lines eyelids
Tunics of the Eyeball
• Sclera
• Choroid coat
• Retina
Sclera
1. Outer layer
2. White of the eye
3. Tough coating, helps maintain shape of
eye
4. Muscles responsible for moving eye
attached to sclera = extrinsic muscles
Choroid coat
1. Middle layer of eye, contains blood
vessels to nourish eyes
2. Opening in front is pupil
3. Colored, muscular layer surrounding pupil
is iris
4. Intrinsic muscles – change size of iris to
control amount of light entering through
pupil
Retina
1. Innermost layer
2. Light rays focus image on retina
3. Image travels to the cerebral cortex via optic
nerve
4. Rods –special cells sensitive to dim light
5. Cones – special cells sensitive to bright
light and color
6. Optic disc – on retina, known as blind spot,
nerve fibers that form optic nerve
Other Special Structures
• Lens
1. Crystalline structure located behind iris and pupil
2. Elastic, disc-shaped, biconvex
3. Situated between the anterior and posterior
chambers
• Anterior Chamber- filled w/ Aqueous humor
• Posterior Chamber- filled w/ Vitreous humor
• Muscles
Internal Anatomy of Eye
Internal Anatomy of Eye
Diseases and Abnormal
Conditions
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•
•
•
•
Amblyopia – lazy eye
Astigmatism
Cataract
Conjuctivitis – pink eye
Glaucoma
Diseases and Abnormal
Conditions (continued)
•
•
•
•
Hyperopia – farsightedness
Myopia – nearsightedness
Presbyopia
Strabismus
Ophthalmoscope.
In addition to examining
the cornea, lens, and
vitreous humor for
opacities (cloudiness),
the examiner can see
the blood vessels at the
back of the eye (fundus)
and note degenerative
changes in the retina.
The Ear: Hearing and Balance
• Controls hearing and balance
• Sound waves transmitted to the
auditory nerve
• Auditory nerve relays information to the
brain for interpretation
• Consists of the outer ear, middle ear, and
inner ear
Outer Ear
• Pinna or auricle
a. Visible ear
b. Collects sound waves
• External auditory canal- ear canal
• Tympanic membrane-– ear drum, separates
outer and middle ear
Middle Ear
1. Cavity in temporal bone
2. Connects with pharynx by Eustachian
tube - which equalizes pressure in the
middle ear with outside atmosphere
3. Bones - transmit sound waves from ear
drum to inner ear
a. Malleus (hammer)
b. Incus (anvil)
c. Stapes (stirrup)
Inner Ear
1. Cochlea - spiral shaped organ of hearing, contains a
membranous tube,the cochlear duct – which is filled with
fluid that vibrates when soundwaves are transmitted by
the stapes
2. Organ of Corti – delicate hairlike cells that pick up
vibrations of fluid andtransmit them as a sensory impulse
along the auditory nerve to the brain
3. Semicircular canals – three structures in inner ear that
contain liquid setin motion by head and body movements
4. Impulses sent to cerebellum to help maintain body
balance (equilibrium)
Internal Anatomy of Ear
Internal Anatomy of Ear
Diseases and Abnormal
Conditions
•
•
•
•
•
Hearing loss
Meniere’s disease
Otitis externa
Otitis media
Otosclerosis
The Chemical Senses: Taste and Smell
• Taste receptors located on the tongue
• Four main tastes
– Sweet
– Salty
– Sour
– Bitter
Sense of Smell
• Nose is the organ of smell
• Olfactory receptors in nasal cavity
• Impulses carried from the olfactory nerve
to the brain for interpretation
• Humans can detect over 6,000 smells
• Sense of taste and smell related