Chapter 11- Part 1 The Eye

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Special Senses

sight, hearing and balance, taste and smell

General Senses

are scattered throughout various regions of the body. These include the sensations of heat, cold, pain, nausea, hunger, thirst, and pressure or touch.

Cutaneous Senses

are receptors of the skin and include touch, heat, cold, and pain.

Visceral Senses

include nausea, hunger, thirst, and the need to urinate and defecate.

Controversial Sense

By "reading your mind," we see you already identified it as extrasensory perception or ESP.

Orbit or Orbit Cavity

is a cone-shaped cavity formed by the skull

Eyeball

a one-inch sphere

Eyelids

protecting the eye is a pair of movable folds of skin

Eyelashes

help prevent large particles form entering the eye.

Sebaceous Glands

secrete sebum onto the eyelids to keep them soft, pliable, and little sticky to trap particles.

Conjunctiva

protective membrane that covers the exposed surface of the eyeball and protects the exposed eye surface.

Lacrimal Apparatus

produces and stores tears.

Lacrimal Gland

produce tears, which are needed for constant cleansing and lubrication and which are spread over the eye surface by blinking.

Antiseptic

to help keep the eyeballs free of germs

Humors

"fluids of the eye"

Aqueous Humor

"watery" humor, bathes the iris, pupil, and lens and fills the anterior and posterior chambers, in the front of the eye.

Vitreous Humor

which maintains eye shape and refracts light rays, is a clear, jellylike fluid that occupies the entire eye cavity behind the lens.

Sclera

is the outermost layer and is a tough, fibrous tissue that serves as the protective shield we commonly call the "whites of the eye."

Cornea

the sclera contains a specialized portion called the _________ (window of the eye), which contains no blood vessels and is transparent to allow light rays to pass into the eye.

Choroid Layer

the middle layer, is a highly vascularized and pgmented region that provides nourishment to the eye.

Iris

located in the choroid layer this is the colored portion of the eye that controls the size of the opening (pupil) where light passes into the eye. It is a sphincter, which means it has intrinsic muscles that can relax or contract depending on light conditions.

Pupil

round opening in the iris that allows light rays to enter the internal eye

Retina

the third and intermost layer. This area contains the nerve endings that receive and interpret the rays of light.

Ciliary Muscles

can alter the shape of the lens, making it thinner or thicker to change the angle of refraction, which allows the focusing of incoming light rays on the retinal area.

Accommodation

combines changes in the size of the pupil and the lens curvature to make sure the image converges in the same place on the retina and therefore is properly focused.

Optic Disk

the area where the neurons of the optic nerve exit the retina

Eye Muscles

six short muscles that provide support and rotary movement

Optic Nerve

the retina is a delicate membrane that continues posteriorly and narrows to become the ________.

Rods

are active in dim light and do not perceive color

Cones

are active in bright light and do perceive color

Photopigments

the rods and cones contain__________that cause a chemical change when light hits them

Blind Spot

lacks rods and cones, so it cannot sense light or color

Stye or hordeolum

is an abscess that forms at the base of an eyelash due to infection of a sebaceous gland. Often the result of bacterial infections, _______are red, swollen, and painful.

Conjunctivitis

is an inflammation of the membrane that lines the eye, and is characterized by red swollen eyes. This condition can be caused by a variety of irritants such as fumes or onions. Plathogens such as viruses and bacteria can also be a culprit.

Pinkeye

acute infective phase of conjucntivitis; it is a highly contagious form caused by staphylococcus aureus bacteria

Trachoma

chronic conjunctivitis and is caused by Chlamydia trachomatis

Cataract

is a condition in which the lens loses its flexibility and transparency and light cannot easily pass through the clouded lens.

Glaucoma

is caused by increased pressure in the fluid of the eye, which interferes with optic nerve functioning, and can also lead to blindness.

Macular Degeneration

is the reduction or loss of central vision in which peripheral vision is unaffected.

Atrophic

dry eye

Exudative

hemorrhagic of the eye

Retinopathy

irreversible damage to the retina can be caused by hypertension or diabetes.

Hyperopia

farsightedness

Presbyopia

farsightedness that occurs with age, usually between 40 and 45 years. The lens becomes stiff and yellowish.

Bifocals

corrective lenses

Myopia

nearsightedness

Amblyopia

lazy eye, causes poor vision in one eye because of the abnormal dominance of the other eye, which does most of the work.

Diplopia

the brain perceives two images, so a person affected by _________has double vision.

Strabismus

one eye is misaligned due to an inablility in the muscles of the eye to coordinate movement with th other eye. cross-eyed appears.

Nyctalopia

degeneration of the retina can cause difficulty seeing at night or in dim light...often caused by a vitamin A deficiency.

Red-Green Color Blindness

people with this condition can see colors but can't distinguish the difference between red and green.

Snellen Chart

eye care professionals and others often meaure visual acuity using an eye chart

Jaundice

yellow tint to the conjucntiva can be a sign of liver disease

PERLA

a neurological assessment...which stands for pupils equal, reactive light and accommodation, can be used to assess brain injury.

REM

rapid eye movement, stage of sleep is measured during sleep studies and helps to diagnose sleep disorders.

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