YOUR EYES & EARS; AND THE BENEFITS OF SLEEPObjectives:

1. Explain how your eyes allow you to see.

2. Identify two ways to keep your eyes healthy.

3. Explain how your ears allow you to hear and maintain your balance.

4. Identify ways to keep your ears healthy.

5. Describe why sleep is important for good health.

Your EyesComplex organs

that respond to light by sending impulses to the brain.

The brain interprets the impulses as images.

HOW LIGHT ENTERS YOUR EYE When light strikes the eye it

passes through a thin layer of tissue that covers the front of the eye called the cornea.

The light travels through the pupil, the opening through which light enters the eye.

The iris is the colored structure that surrounds the pupil and regulates its size.

The light then strikes a lens, a flexible tissue that focuses the light and produces an upside down image.

HOW LIGHT ENTERS YOUR EYE, CONT.

After passing through the lens, the focused light strikes the back of the eye called the retina.

The retina contains 130 million cells called rods and cones that respond to light.

Rods work best in dim light and help you see in black & white

Cones work best in bright light and allow you to see color.

The optic nerve receives the light impulses and sends it’s message to the brain where the brain combines the information and produces a right-side up image.

CARING FOR YOUR EYES It is important to

care for your eyes. Wear protective eye

goggles when playing some sports or working around machinery.

Wear sunglasses that provide UV protection.

Have regular eye exams.

EYE CARE TIPS• Blink often when

using a computer.• Look away from a

computer or television every 30 minutes for about 10 seconds.

• Do no rub your eyes.

• If you wear contact lenses, follow your doctor’s instructions.

• Eat foods rich in vitamin A.

• When outdoors, wear sunglasses that provide 100% UV-ray protection.

YOUR EARSThe ears convert sounds

into nerve impulses that your brain interprets.

Structures in the ear detect the position and movement of your head. It helps you to stand upright, walk smoothly, and adjust your body’s position.

STRUCTURE OF THE EAR

Outer Ear: sounds travel to the ears as vibrations. The vibrations travel to the eardrum (vibrates when struck).

Middle Ear: the vibrations pass to 3 small bones, the hammer, the anvil, and the stirrup.

Inner Ear: vibrations then move to the oval window and to the cochlea, a hollow tube filled with fluid and hair like cells that senses the vibrations. The impulses are carried to the brain by way of the auditory nerve.

Balance: Semicircular canals in the inner ear signals balance to the brain.

Outer ear

Cochlea

Auditory Nerve

Semicircular canals

CARING FOR YOUR EARS Keep your ears clean.

Use a wash cloth and clean the outer ear. Never use Q tips inside the ear canal.

Monitor noise levels. Question: Name some

loud noises we deal with daily?

Treat ear infections. Hearing loss can be the result of infection.

Treat hearing problems.

SLEEP What is sleep?

Deep relaxation of the body and mind.

Eyes are closed. There is little

conscious thought or movement.

Muscles relax. Heart rate and

breathing decrease

Sleep is as important as air, water, and food!

BENEFITS OF SLEEPScientists have yet to agree on the reason why people sleep. The brain sorts the

day’s information. Learning and storing memories occur.

Healing the body tissues .

Adequate sleep helps the immune system to function.

Adequate sleep helps to prevent some diseases, such as diabetes.

TEENS AND SLEEP

Some effects of sleep loss:• Depression• Problems focusing

and paying attention.

• Difficulties learning• Increased risk of

illness• Increased risk of

accidents.

Circadian rhythm: the body’s internal clock that regulates behavior patterns.

Puberty affects the body’s circadian rhythm resulting in a change of sleep habits.

Teens need 9 hours of sleep nightly, but most get 7 hours.• Go to bed and wake

up at the same time.• Avoid bright lights at

night, enjoy the light in the morning.

• Avoid sugary foods and caffeine before bed.

• Do not let naps interfere with your night sleep.

GOOD HEALTH REVIEW1.List the structures in the eye through

which light passes to allow you to see an image.

2.List two ways you can keep your eyes healthy.

3.Trace the path of sound from your outer ear until it is perceived by your brain.

4.List three ways you can keep your ears healthy.

5.List three possible benefits of sleep and three effects of sleep loss.

6.List three possible methods of avoiding circadian rhythm interference.