“Scrub In” What is the function of vitreous humor? a. Maintain eye shape and provide color vision b. Maintain eye shape and refract light rays c. Provide night vision and color vision d. Provide night vision and refract light rays What does the pupil do when exposed to bright light? a. Constrict b. Dilate c. Enlarge d. Nothing 3.04 Understand the functions and disorders of the sensory system 1
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“Scrub In”
What is the function of vitreous humor? a. Maintain eye shape and provide color vision
b. Maintain eye shape and refract light rays
c. Provide night vision and color vision
d. Provide night vision and refract light rays
What does the pupil do when exposed to bright light?
a. Constrict
b. Dilate
c. Enlarge
d. Nothing
3.04 Understand the functions and
disorders of the sensory system 1
3.04 Functions and
disorders of the eye
3.04 Understand the functions and
disorders of the sensory system 2
3.04 Understand the functions and
disorders of the sensory system
3.04 Understand the functions and
disorders of the sensory system 3
Essential Questions
• What are the functions of the sensory system?
• What are some disorders of the sensory system?
• How are sensory system disorders treated?
• How do you relate the body’s communication to
the sensory system?
Understanding the
functions of the eye
3.04 Understand the functions and
disorders of the sensory system 4
Understanding the
functions of the eye External eye Orbit – protects the eye
Eyelids and eyelashes -
protect the eyes from small particles; provide a danger warning
Conjunctiva – secretes mucous to lubricate the eye
Lacrimal glands – produce tears Extrinsic muscles –
responsible for moving the eye and are attached to the sclera
3.04 Understand the functions and
disorders of the sensory system 5
Understanding the
functions of the eye Internal eye
Intrinsic muscles –
changes size of the
iris and pupil to
control amount of
light entering
through the pupil
3.04 Understand the functions and
disorders of the sensory system 6
Understanding the
functions of the eye
Internal eye
Cornea – helps the eye focus
Iris - controls the diameter and size of the pupil
Pupil - allows light to enter the retina/ constricts when exposed to bright light
3.04 Understand the functions and
disorders of the sensory system 7
Understanding the
functions of the eye Internal eye
Ciliary body – holds the lens in place with the suspensory muscles
Lens – focuses light rays on the retina and controls the process of accommodation (change in the shape of the lens to allow for near and distance vision)
Aqueous humor - nourishes the cornea and the lens and gives the eye it's shape.
3.04 Understand the functions and
disorders of the sensory system 8
Understanding the
functions of the eye Internal eye Sclera – helps
maintain the shape of the eye and protects what’s inside
Choroid – provides oxygen and nourishment to the outer layers of the retina
Retina - transmits images to the brain
3.04 Understand the functions and
disorders of the sensory system 9
Understanding the
functions of the eye
Internal eye
Vitreous humor –
maintains eye
shape and refracts
light rays
3.04 Understand the functions and
disorders of the sensory system 10
Understanding the
functions of the eye
3.04 Understand the functions and
disorders of the sensory system 11
Macula: responsible for
clear, sharp central
vision
Understanding the
functions of the eye
Pathway of vision:
Cornea→Pupil→Lens→Retina→Optic Nerve
3.04 Understand the functions and
disorders of the sensory system 12
Why can’t you see in the dark?
Rods and cones of the retina
Functions of the rods and cones: they are sensitive
to light; cones are responsible for color vision 13
Understanding the
functions of the eye
“Scrub In” What is the medical term for a tiny abscess at the base of
an eyelash?
a. Hordeolum
b. Cataract
c. Blind spot
d. Rod
What is another name for nearsightedness:
a. Myopia
b. Hyperopia
c. Astigmatism
d. Amblyopia
3.04 Understand the functions and
disorders of the sensory system 14
Disorders of the eye
3.04 Understand the functions and
disorders of the sensory system 15
Cataract
Glaucoma
Diabetic retinopathy
Have you heard of these conditions?
What do you know about them?
Disorders of the eye
Lens of eye gradually
become cloudy
Frequently occurs in
people over 70
Causes a painful,
gradual blurring and loss
of vision
Pupil turns black to milk
white
3.04 Understand the functions and
disorders of the sensory system 16
Cataract
Disorders of the eye
Cataract
Treatment:
Surgical removal
of the lens
3.04 Understand the functions and
disorders of the sensory system 17
Disorders of the eye
Color blindness
Do you see the number?
What is color blindness: the
inability to distinguish
colors
Causes: hereditary
Who is most likely to have
color blindness: males
3.04 Understand the functions and
disorders of the sensory system 18
Disorders of the eye
Conjunctivitis (Pink eye)
Inflammation of the
conjunctival membranes in front
of the eye/ very contagious
Symptoms: redness, pain,
swelling and discharge
Causes: bacteria or virus
Treatment: antibiotic eye drops
if bacterial 3.04 Understand the functions and
disorders of the sensory system 19
Detached retina – is when the retina pulls away from the
layer of blood vessels that provides it with oxygen and
nourishment.
3.04 Understand the functions and
disorders of the sensory system 20
The longer it goes
untreated the higher
the risk is of
permanent damage
3.04 Understand the functions and
disorders of the sensory system 21
Detached retina
Causes: shrinkage or
contraction of the vitreous
humor, injury, advanced
diabetes, an inflammatory
eye disorder
Treatment: surgery
Disorders of the eye Diabetic retinopathy - a complication of diabetes that affects the eyes; caused by changes in the blood vessels in the retina
Causes: elevated glucose levels over an extended period of time
Symptoms: floaters, blurred vision, dark areas in your vision, vision loss
Treatment: laser surgery
3.04 Understand the functions and
disorders of the sensory system 22
Disorders of the eye Glaucoma – excessive
intraocular pressure causing
destruction of the retina and
atrophy of the optic nerve
Symptoms: develop gradually
– mild aching, loss of
peripheral vision, halo around
light
Diagnosed: Tonometer
(measures intraocular pressure)
Treatment: drugs or laser
surgery to lower the intraocular
pressure 3.04 Understand the functions and
disorders of the sensory system 23
Disorders of the eye Macular degeneration
Is a chronic eye disease that causes vision
loss in the center of your field of vision.
There are 2 types:
Dry – causes gradual thinning of the
retina
Wet – abnormal blood vessels grow
behind the macula causing fluid or
blood to leak. This leads to distortion
of the maculas shape.
Diagnosis: eye exam, Amsler grid,
angiogram
Treatment: high doses of antioxidants and
zinc, surgery 24
3.04 Understand the functions and
disorders of the sensory system 25
Compare the symptoms and treatments of these
common eye disorders.
Can a person have more than one of these disorders?
26
Presbyopia – lens loses elasticity, can’t
focus on close or distant objects
Treatment: bifocals
Hyperopia – farsighted; focal point
beyond the retina because eyeball is too
short. Would need glasses to see things
up close.
Treatment: convex lenses
Myopia – nearsighted; eyeball is
enlongated. Would need glasses to see
things far away
Treatment: concave lenses
Astigmatism – irregular curvature of
the cornea or lens, causing blurred vision
and eye strain
Treatment: corrective lenses
Testing vision Someone with eye problems would need to see
an Ophthalmologist.
An ophthalmoscope is an instrument for
viewing inside of the eye
Snellen eye chart – chart that uses letters or
symbols in calibration to check for vision
defects
What is 20/20: normal vision. This means that
the patient sees the same line of letters at 20 feet