SENSES EYE EAR INTERGUMENTARY SYSTEM SKIN The Senses

SENSES (EYE & EAR) & INTERGUMENTARY SYSTEM (SKIN)

The Senses

General Senses n Distributed throughout body q q q Pain Touch Pressure Temperature Proprioception

Special Senses n n n Located within complex sense organs Gustation = sense of taste Olfaction = sense of smell Hearing Equilibrium Vision

The Ear n n Used for both hearing and equilibrium Divided into three parts q Outer ear n n Pinna (auricle) External auditory canal (meatus) q n Contains cerumen (earwax) Tympanic membrane (eardrum) q Transmits sound waves to middle ear

The Ear (con’t) n Middle ear q Houses three ossicles n n n Malleus (hammer) Incus (anvil) Stapes (stirrup) Soundwaves are transmitted from footplate of stapes Eustachian tube q q n n Connects middle ear to nasopharynx Equalizes pressure between outer and middle ear

The Ear (con’t) n Inner ear q q q Complex labyrinth shape Filled with fluid Contains cochlea n Organ of Corti Vestibular apparatus n Sense of equilibrium n Semicircular canals Vestibulocochlear nerve n Cochlear branch transmits hearing impulses n Vestibular branch transmits equilibrium impulses

Otitis n Inflammation of the ear q Otitis media = infection leading to accumulation of fluid in middle ear n Causes q q n Obstruction of eustachian tube caused by Spreading infection Treatment q q Antibiotics Myringotomy

Otitis (con’t) q Otitis externa n n n Inflammation of external auditory canal Also known as “swimmer’s ear” Caused by: q q n Fungus Bacterium Common among: q q People living in hot climates Swimmers

Meniere Disease n n Involves production and circulation of inner ear fluid Symptoms q q n Vertigo (dizziness) Hearing loss Tinnitus (ringing in ears) Pressure Treatment q q Drugs (to treat nausea and dizziness) Severe cases n Inner ear or eighth cranial nerve destroyed surgically

The Eye and Vision n Eye has three layers q Sclera n Outermost layer n Known as “White of the eye” n Extends over front of eye as transparent cornea

Uvea n Uvea q q Middle, vascular layer Consists of: n n Choroid Ciliary body q q n Muscle controls shape of lens Allows for accommodation Iris q q q Muscular ring Controls size of pupil Determines eye color

Retina n n n Innermost layer Actual visual receptor Consists of specialized cells: q Rods n n n q Function in dim light Low visual acuity Do not respond to color Cones n n n Active in bright light High visual acuity Respond to color

Eye Protection n n Orbit = bony socket Eyelids q n n Conjunctiva n Thin membrane n Covers anterior portion of eye Eyebrows Eyelashes Tears Lacrimal glands q q Bathe eyes with lubricating fluid Fluid drains into nose

Errors of Refraction n Myopia = nearsightedness q q n Hyperopia = farsightedness q q n n 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 n Conjunctivitis = inflammation of conjunctiva q q n Trachoma = inflammation of cornea and conjunctiva q q n Commonly known as “pinkeye” Highly infectious Results in scarring Common cause of blindness in 3 rd world countries Ophthalmia neonatorum = acute conjunctivitis in newborns q Caused by gonorrhea

Disorders of Retina n Retinal detachment q Separation of retina from choroid q Caused by: n n Tumor Hemorrhage Injury to eye Repaired with laser surgery

Cataract n Opacity of lens caused by: q q n Disease Injury Chemicals Exposure to UV rays Must be removed to prevent blindness q q Anterior capsule removed Phacoemulsification

Glaucoma n n n Increased pressure within eyeball More aqueous humor produced than can be drained away Leads to blindness Many causes Screening at routine eye exams Treatment q q Medication Surgery

Integumentary system: THE SKIN, NAILS, & HAIR