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Mod 6 Ch 26
Eye, Ear, and other senses
Term | Definition |
---|---|
orbit | cavity in skull where the eyeball is housed |
Outer Layer of the eye | sclera, cornea (window), limbus |
sclera | outer layer, white of the eye, light is unable to penetrate |
cornea | outer layer, "window" of the eye, allows light to enter |
limbus | outer layer, corneal-scleral junction |
Middle Layer of the eye | choroid, iris, lens, pupil ("hole" in center of iris) |
choroid | middle layer of the eye, lines the sclera, absorbs extra light entering the eye |
iris | middle layer of the eye, contains the eye color (or pigment), has a "hole" in the center called the pupil |
lens | middle layer of the eye, colorless structure behind the iris, sharpens the focus of light rays into the retina |
Inner Layer of the eye | retina, optic nerve |
retina | inner layer of the eye, contains photosensitive cells called rods and cones that translate light rays into nerve impulses that are translated to the brain |
rods | photosensitive cells in retina that react to dim light and are used in night vision |
cones | photosensitive cells in the retina that react to bright light and color |
optic nerve | inner layer of the eye, enters at the optic disc and carries incoming information from the eye to the brain |
palpebrae | eyelids |
conjunctiva | mucous membrane that lines the underside of eyelids and anterior of eyeball |
lacrimal canaliculi | ducts (2) at the corner of each eye which collect and drain tears into the lacrimal sac. |
lacrimal sac | area where tears are collected and drain into nasolacrimal duct |
astigmatism | condition caused by irregularity in the curvature of the cornea (more football-shaped than round) |
strabismus | crossed eyes or wall eyes |
Refraction problems | Inability to focus correctly. Include myopia (near-sighted), hyperopia (far-sighted) and presbyopia (eye changes with age) |
blepharoptosis | droopy eyelid |
blepharitis | inflammation of the eyelids |
conjunctivitis | AKA pinkeye, highly contagious |
hordeolums | AKA sties, accompany blocked or infected eyelids or glands, frequently contagious |
Age-related eye disorders | cataracts, retinal detachment, macular degeneration |
cataract | clouding or opacity of the lens |
retinal detachment | retina separates from the choroid layer |
macular degeneration | deterioration of the macula (central portion of the retina), incurable, leading cause of blindness in people 55+ |
amblyopia | AKA lazy eye, the nerve pathway from the eye to the brain doesn't properly develop. |
corneal abrasion | scratch or lesion on the cornea |
glaucoma | Increased IOP caused by build-up of fluid (aqueous humor), can lead to damage of the optic nerve and blindness. |
nystagmus | involuntary, repetitive rhythmic eye movements |
retinopathy | nerve damage caused by recurring or acute damage (diabetic retinopathy) |
Outer Ear | Pinna, auditory meatus, tympanic membrane, fundus |
pinna | AKA auricle, visual portion of the outside of ear |
auditory meatus | auditory canal, secretes cerumen (earwax) |
tympanic membrane | AKA ear drum, separates the outer ear from the middle ear and transmits sound vibrations into the middle ear |
fundus | floor of the tympanic cavity |
Middle Ear | Contains eustachian tube and 3 small bones or ossicles: malleus, incus, and stapes. The middle ear transmits sound vibrations, equalizes pressure, and protects from loud noises. |
eustachian tube | auditory tube that extends 3-4 cm to nasopharynx |
three small bones (ossicles) of middle ear | malleus, incus, stapes |
Inner Ear | Contains maze of canals called labyrinth, cochlea "organ of hearing", and vestibule |
cochlea | "organ of hearing", bony spiral structure that looks like snail's shell |
vestibule | fundus of the internal auditory meatus (floor of the internal ear canal) which controls the sense of balance. |
audiology | study of hearing disorders including loss |
2 types of hearing loss | conductive and sensorineural |
conductive hearing loss | temporary condition in which sound is not conducted efficiently through the auditory canal to the eardrum and middle ear. Can be caused by obstruction, impacted wax, or allergies. |
sensorineural hearing loss | permanent hearing loss caused by damage to the cochlea or nerve pathways from inner ear to brain. |
Common Outer Ear disorders | Impacted cerumen and ruptured tympanic membrane |
impacted cerumen | earwax that has accumulated and hardened to the point of obstructing the auditory canal |
ruptured tympanic membrane | ripping or tearing caused by objects or unequal air pressure |
Common Middle Ear disorders | Otitis media and otosclerosis |
Otitis media | AKA middle ear infection caused by viral and bacterial infections |
otosclerosis | abnormal tissue growth around the stapes, usually hereditary |
Common Inner Ear disorders | Tinnitus, Meniere's disease, and presbycusis |
Tinnitus | ringing or roaring in one or both ears, usually symptom associated with many forms of hearing loss |
Meniere's disease | A disease that affects a person's balance and hearing due to changes in fluid volume in labyrinth of the inner ear. |
presbycusis | hearing loss associated with aging to due gradual deterioration of the sensory receptors in older adults. |
Nose | Primary organ for sense of smell, contains olfactory cells |
olfactory cells | found in nasal cavity that respond to changes in odor and chemical concentrations |
gustatory cells | found in taste buds on tongue, roof of mouth, and throat that serve as taste receptors |
4 types of taste cells | sweet, sour, salty, and bitter |
sense of touch | oldest and most primitive sense that originates in the dermis |