Download 3.03 Understand the sensory system

Eyes
3.03 Remember the structures of the sensory system
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Warm up

Read pages in textbook. Fill out handout.
3.04 Understand the functions and
disorders of the sensory system
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Structures of the eyes
 External
structures
Orbit
Eyelids
Eyelashes
Conjunctiva
Lacrimal apparatus
Extrinsic muscles
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3.03 Remember the structures of the sensory system
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Structures of the eyes
1” in diameter
 Protected by orbital socket of skull,
eyebrows, eyelashes and eyelids
 Bathed in fluid from LACRIMAL
GLANDS – tears empty into nasal
cavity
 CONJUNCTIVA – thin membrane
that lines the eyelids and covers part
of the eye, secretes mucous to
lubricate eye
 Wall of the eye made up of three coats
(sclera, choroid coat, retina)
Two Chambers
 Anterior containing iris, ciliary body
and lens
 Posterior- retina, macula, optic nerve.
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3.03 Remember the structures of the sensory system
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Eye
External eye
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Orbit
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Eyelids and eyelashes
Women blink twice as often
as men. Why do we blink?
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Conjunctiva
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Lacrimal apparatus
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Extrinsic muscles
3.04 Understand the functions and
disorders of the sensory system
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Eye
External eye
Extrinsic
muscles- 4
Superior
rectus, Inferior
rectus, Medial
rectus and
Lateral rectus
3.04 Understand the functions and
disorders of the sensory system
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Internal eye
Sclera
Eye
Outer
layer
White of the eye
Tough coating, helps
maintain shape of eye
and protects what’s
inside
Muscles responsible for
moving the eye are
attached to the sclera –
called EXTRINSIC
MUSCLES
3.04 Understand the functions and
disorders of the sensory system
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Internal eye
Eye
Cornea-
the transparent front part
of the eye that covers
the iris, pupil,
and anterior chamber
Refracts light.
Choroid CoatLayer of the sclera that
contains the blood
vessels-Blood supply to
the eye
3.04 Understand the functions and
disorders of the sensory system
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Internal eye
 Iristhin, circular structure in
the eye, responsible for
controlling the diameter
and size of the pupil-the
amount of light
reaching the retina. The
color of the iris is often
referred to as “ eye color
“
 Pupil
a hole located in the
center of the iris of
the eye that allows light
to enter the retina
Eye
3.04 Understand the functions and
disorders of the sensory system
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Eye
Internal eye
Ciliary
body- Muscles
inside the eye -has three
functions: accommodation,
aqueous humor production
and the production and
maintenance of the lens
zonules
Lens-
a nearly transparent
biconvex structure suspended
behind the iris of the eye, the
sole function of which is to
focus light rays onto the
retina
3.04 Understand the functions and
disorders of the sensory system
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Internal eye
Aqueous humor
clear, watery fluid
circulating in the
chamber of the eye
between the cornea
and the lens.
- nourishes the
cornea and the lens
and gives the eye
it's shape.

Eye
3.04 Understand the functions and
disorders of the sensory system
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Internal eye


Vitreous humorclear gel that
fills the space
between the lens
and the retina.
Helps keep the
retina in place
Eye
3.04 Understand the functions and
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Eye
Internal eye
CHOROID
COAT
Middle
layer
Blood Supply to retina
Opening in front is the
PUPIL
Colored, muscular layer
surrounding pupil is IRIS
INTRINSIC
MUSCLES – change
size of iris to control
amount of light entering
through the pupil
3.04 Understand the functions and
disorders of the sensory system
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Internal eye
RETINA
Innermost
layer
Light rays focus an
image on the retina
The image travels to
the cerebral cortex via
the OPTIC NERVE
Receives light
focused from the lens,
convert the light into
neural signals, and
send these signals on
to the brain.
Eye
3.04 Understand the functions and
disorders of the sensory system
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Eyes
 Rods
and cones- specialized nerve fiber in
the retina.
 Rods- Located on the pouter edges of the
retina
 Do not perceive color
 Function in dim light allowing us to
see and also helps with peripheral
vision
 Cones
 Active in bright light and allow you to
precieve color
 If you don’t have cones you are
Remember the structures of the sensory system
considered3.03color
blind.
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Internal eye
OPTIC DISC –
Located on the
retina on the back
of the eye.
 Known as the
blind spot – nerve
fibers gather here
to form the optic
nerve, no rods or
cones
1 Million Neurons
Eye
3.04 Understand the functions and
disorders of the sensory system
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Eye

a small and highly
sensitive part of
the retina responsible
for detailed central
vision.
3.04 Understand the functions and
disorders of the sensory system
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Process of Seeing
Eye
Trace
the field
of vision.
Light
Cornea
Pupil
Lens
(where light rays are
refracted)
Retina
Rods and Cones (pick up
stimulus)
Optic Nerve
Brain
Is there anything strange about
this picture? Explain
Why can’t you see in the dark?
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Eye
Vision
What happens as you move
your paper away from and
toward to your eye?
3.04 Understand the functions and
disorders of the sensory system
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Eyes
Name the structures…
 Review
3.03 Remember the structures of the sensory system
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3.04 Understand the functions and
disorders of the sensory system
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Vision Activity
Do you see what I see?
http://www.illusions.org/
3.04 Understand the functions and
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Disorders of the eye
Glaucoma
Diabetic retinopathy
Cataract
Have you heard of these conditions?
What do you know about them?
3.04 Understand the functions and
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Disorders of the eye
Cataract
Describe this lens.
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Disorders of the eye
Cataract
How is a
cataract
treated?
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Disorders of the eye
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CATARACTS
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Lens of eye gradually
becomes cloudy
Frequently occurs in
people over 70
Causes a gradual
blurring and loss of
vision
Pupil turns from
black to milky white
Rx – surgical removal
of the lens
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Disorders of the eye
Color blindness
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Do you see the number?
Unable to distinquish
between the colors red
and green. Will most
often only be able to see
black, white and gray.
A decrease in the number
of rods in the eye.
Men are more likely to
be color blind 3.04 Understand the functions and
disorders of the sensory system
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Disorders of the eye
Conjunctivitis
 Pink eye
 Inflammation of
conjunctival membranes
in front of the eye
 Redness, pain, swelling
and discharge
 Highly contagious
 Rx – antibiotic eye drops
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disorders of the sensory system
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Detached retina
Discuss what happens
in this process.
What is the relevance
to health?
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Detached retina
Compare this process
to the previous picture.
What might cause this
condition?
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Disorders of the eye
Diabetic
retinopathy
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What causes
diabetic
retinopathy?
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What are the
symptoms?
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Explain the impact
on vision.
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Disorders of the eye
Glaucoma
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Excessive intraocular pressure
causing destruction of the
retina and atrophy of the optic
nerve
Caused by overproduction of
aqueous humor, lack of
drainage, or aging
Sx – develop gradually – mild
aching, loss of peripheral
vision, halo around the light
TONOMETER – measures
intraocular pressure
Rx – drugs or laser
surgery
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Disorders of the eye
Macular degeneration
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What is macular degeneration?
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Compare the two types.
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How is it diagnosed?
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What is the treatment?
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3.04 Understand the functions and
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PRESBYOPIA
 Lens loses elasticity, can’t focus on close or
distant objects
 Usually occurs after age 40
 Rx – Bifocals
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HYPEROPIA
 Farsighted
 Focal point beyond the retina because
eyeball too short
 Convex lenses
3.04help
Understand the functions and
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disorders of the sensory system
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MYOPIA
 Nearsighted
 Eyeball too long
 Concave lenses help
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ASTIGMATISM
 Irregular curvature of the cornea or lens,
causing blurred vision and eye strain
 Rx – corrective lenses
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3.04 Understand the functions and
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Testing vision
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SNELLEN EYE
CHART – chart that
uses letters or symbols
in calibrated heights to
check for vision defects
3.04 Understand the functions and
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Processing
Labeling Activity 1
 Look into my eyes
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