Transcript Eye, ear, skin

SENSES (EYE & EAR) &
INTERGUMENTARY SYSTEM
(SKIN)
The Senses
General Senses
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Distributed throughout body
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Pain
Touch
Pressure
Temperature
Proprioception
Special Senses
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Located within complex sense organs
Gustation = sense of taste
Olfaction = sense of smell
Hearing
Equilibrium
Vision
The Ear
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Used for both hearing and equilibrium
Divided into three parts
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Outer ear
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Pinna (auricle)
External auditory canal (meatus)
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Contains cerumen (earwax)
Tympanic membrane (eardrum)
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Transmits sound waves to middle ear
The Ear (con’t)
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Middle ear
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Houses three ossicles
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Malleus (hammer)
Incus (anvil)
Stapes (stirrup)
Soundwaves are transmitted from footplate of
stapes
Eustachian tube
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Connects middle ear to nasopharynx
Equalizes pressure between outer and middle ear
The Ear (con’t)
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Inner ear
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Complex labyrinth shape
Filled with fluid
Contains cochlea
 Organ of Corti
Vestibular apparatus
 Sense of equilibrium
 Semicircular canals
Vestibulocochlear nerve
 Cochlear branch transmits hearing impulses
 Vestibular branch transmits equilibrium impulses
Otitis
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Inflammation of the ear
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Otitis media = infection leading to accumulation of
fluid in middle ear
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Causes
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Obstruction of eustachian tube caused by
Spreading infection
Treatment
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Antibiotics
Myringotomy
Otitis (con’t)
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Otitis externa
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Inflammation of external auditory canal
Also known as “swimmer’s ear”
Caused by:
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Fungus
Bacterium
Common among:
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People living in hot climates
Swimmers
Meniere Disease
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Involves production and circulation of inner ear fluid
Symptoms
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Vertigo (dizziness)
Hearing loss
Tinnitus (ringing in ears)
Pressure
Treatment
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Drugs (to treat nausea and dizziness)
Severe cases
 Inner ear or eighth cranial nerve destroyed surgically
The Eye and Vision
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Eye has three layers
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Sclera
 Outermost layer
 Known as “White of the eye”
 Extends over front of eye as transparent cornea
Uvea
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Uvea
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Middle, vascular layer
Consists of:
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Choroid
Ciliary body
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Muscle controls shape of lens
Allows for accommodation
Iris
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Muscular ring
Controls size of pupil
Determines eye color
Retina
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Innermost layer
Actual visual receptor
Consists of specialized cells:
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Rods
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Function in dim light
Low visual acuity
Do not respond to color
Cones
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Active in bright light
High visual acuity
Respond to color
Eye Protection
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Orbit = bony socket
Eyelids
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Conjunctiva
 Thin membrane
 Covers anterior portion of eye
Eyebrows
Eyelashes
Tears
Lacrimal glands
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Bathe eyes with lubricating fluid
Fluid drains into nose
Errors of Refraction
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Myopia = nearsightedness
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Hyperopia = farsightedness
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Eyeball too long
Images form in front of retina
Eyeball too short
Images form behind retina
Astigmatism = irregularity in curve of cornea or
lens
Glasses can correct most of these impairments
Infection
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Conjunctivitis = inflammation of conjunctiva
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Trachoma = inflammation of cornea and
conjunctiva
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Commonly known as “pinkeye”
Highly infectious
Results in scarring
Common cause of blindness in 3rd world countries
Ophthalmia neonatorum = acute conjunctivitis in
newborns
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Caused by gonorrhea
Disorders of Retina
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Retinal detachment
 Separation of retina from choroid
 Caused by:
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Tumor
Hemorrhage
Injury to eye
Repaired with laser surgery
Cataract
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Opacity of lens caused by:
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Disease
Injury
Chemicals
Exposure to UV rays
Must be removed to prevent blindness
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Anterior capsule removed
Phacoemulsification
Glaucoma
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Increased pressure within eyeball
More aqueous humor produced than can be
drained away
Leads to blindness
Many causes
Screening at routine eye exams
Treatment
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Medication
Surgery
Integumentary system: THE
SKIN, NAILS, & HAIR