“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

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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

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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

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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

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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.

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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

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disorders of the sensory system 9

Understanding the

functions of the eye

Internal eye

Vitreous humor –

maintains eye

shape and refracts

light rays

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disorders of the sensory system 10

Understanding the

functions of the eye

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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

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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

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Disorders of the eye

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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

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Cataract

Disorders of the eye

Cataract

Treatment:

Surgical removal

of the lens

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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

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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.

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disorders of the sensory system 20

The longer it goes

untreated the higher

the risk is of

permanent damage

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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

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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

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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?

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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

that a normal person sees at 20 feet.

What does PERRLA mean:

Pupils Equal, Round, Reactive to

Light and Accommodation

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