Your Eyes and Ears Chapter 13 Personal Care Your Eyes and Ears Chapter 13

Your Eyes Complex organs that respond to light by sending impulses Brain interprets these impulses at images

The Response of the Eye When rays of light first strike the eye, they enter through the cornea Cornea: clear tissue that covers the front of the eye The light then passes through a chamber filled with liquid that nourishes the eye Finally, the light enters the pupil Pupil: opening through which light enters the eye

The Iris, Lens, and Retina The iris is a circular structure that surrounds the pupil and regulates its size The size of the pupil adjusts based on the amount of light entering the eye The lens is a flexible structure that focuses the light entering the eye The retina is a layer of cells that lines the back of the eye

Diagram of the Eye

Vision Problems Nearsightedness: can see objects that are close, but not those that are far away Caused by an elongated eyeball Farsightedness: can see far away objects, but not those that are close up Caused by an eyeball that is too short Astigmatism: distorted vision because images do not focus correctly on the retina Caused by an uneven curvature in the cornea

Nearsightedness

Farsightedness

Astigmatism

Eye Diseases Optometrist: a professional who provides eye and vision care Types of diseases that take place in the eyes include: Glaucoma Cataracts Detached Retina Macular Degeneration

Glaucoma Caused by a slow drainage of the eye, resulting in a build-up of pressure Can damage the optic nerve and lead to sight problems Common in people with diabetes and high blood pressure

Cataracts The clouding of the eye’s lens that is common among older adults Wearing sunglasses with UV protection and not smoking can help slow the development

Other Eye Diseases Macular Degeneration Detached Retina Aging or an injury to the eye can cause the retina to separate from the eye lining Surgery is the only effective treatment for a detached retina The leading cause of eyesight problems in older adults Occurs when cells in the center of the retina break down and become weak

Anatomy of the Ear

Anatomy of the Ear Outer ear Middle ear Inner ear Sound enters through the outer ear and reaches the ear drum Middle ear Vibrations pass through the middle ear after passing the eardrum Inner ear Vibrations in the cochlea cause nerve cells to transmit signals to the brain

The Inner Ear and Balance Semicircular canals Located above the cochlea in the inner ear Structures that send information to your brain about the movements of your head When your head moves, the fluid inside the canals and stimulates nerve cells to keep the body balanced

Ear Care Keep the ears clean both inside and out Avoid loud noises that are directly aimed towards the inside of the ear Treat ear infections as soon as possible Consult an audiologist when necessary Audiologist: professional who is trained to evaluate hearing and treat hearing loss