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

SENSES (EYE & EAR) & INTERGUMENTARY SYSTEM

(SKIN)

The Senses

General Senses Distributed throughout body

Pain Touch Pressure Temperature Proprioception

Special Senses

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

The Ear

Used for both hearing and equilibrium

Divided into three parts Outer ear

Pinna (auricle) External auditory canal (meatus)

Contains cerumen (earwax) Tympanic membrane (eardrum)

Transmits sound waves to middle ear

The Ear (con’t)

Middle ear Houses three ossicles

Malleus (hammer) Incus (anvil) Stapes (stirrup)

Soundwaves are transmitted from footplate of stapes

Eustachian tube Connects middle ear to nasopharynx Equalizes pressure between outer and middle ear

The Ear (con’t) Inner ear

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

Inflammation of the ear Otitis media = infection leading to accumulation

of fluid in middle ear Causes

Obstruction of eustachian tube caused by Spreading infection

Treatment Antibiotics Myringotomy

Otitis (con’t)

Otitis externa Inflammation of external auditory canal Also known as “swimmer’s ear” Caused by:

Fungus Bacterium

Common among: People living in hot climates Swimmers

Meniere Disease

Involves production and circulation of inner ear fluid

Symptoms Vertigo (dizziness) Hearing loss Tinnitus (ringing in ears) Pressure

Treatment Drugs (to treat nausea and dizziness) Severe cases

Inner ear or eighth cranial nerve destroyed surgically

The Eye and Vision

Eye has three layers Sclera

Outermost layer Known as “White of the eye” Extends over front of eye as transparent

cornea

Uvea

Uvea Middle, vascular layer Consists of:

Choroid Ciliary body

Muscle controls shape of lens Allows for accommodation

Iris Muscular ring Controls size of pupil Determines eye color

Retina Innermost layer Actual visual receptor Consists of specialized cells:

Rods Function in dim light Low visual acuity Do not respond to color

Cones Active in bright light High visual acuity Respond to color

Eye Protection

Orbit = bony socket Eyelids

Conjunctiva Thin membrane Covers anterior portion of eye

Eyebrows Eyelashes Tears Lacrimal glands

Bathe eyes with lubricating fluid Fluid drains into nose

Errors of Refraction

Myopia = nearsightedness Eyeball too long Images form in front of retina

Hyperopia = farsightedness Eyeball too short Images form behind retina

Astigmatism = irregularity in curve of cornea or lens

Glasses can correct most of these impairments

Infection

Conjunctivitis = inflammation of conjunctiva Commonly known as “pinkeye” Highly infectious

Trachoma = inflammation of cornea and conjunctiva Results in scarring Common cause of blindness in 3rd world countries

Ophthalmia neonatorum = acute conjunctivitis in newborns Caused by gonorrhea

Disorders of Retina

Retinal detachment Separation of retina from choroid Caused by:

Tumor Hemorrhage Injury to eye

Repaired with laser surgery

Cataract

Opacity of lens caused by: Disease Injury Chemicals Exposure to UV rays

Must be removed to prevent blindness Anterior capsule removed Phacoemulsification

Glaucoma Increased pressure within eyeball More aqueous humor produced than can be

drained away Leads to blindness Many causes Screening at routine eye exams Treatment

Medication Surgery

Integumentary system: THE SKIN, NAILS, & HAIR