Visual & Auditory Systems. Introduction Five main senses of body system: sight, hearing, touch,...
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Transcript of Visual & Auditory Systems. Introduction Five main senses of body system: sight, hearing, touch,...
Visual & Auditory Visual & Auditory SystemsSystems
IntroductionIntroduction• Five main senses of body system:
sight, hearing, touch, smell, taste,
• Two senses that can change life dramatically: seeing and hearing
The EyesThe Eyes
• Images translate into impulses that create lasting memories in the mind
• Three different levels of eye specialists:
• Opticians make lenses
• Optometrists perform eye exams
• Ophthalmologists are medical doctors
Anatomy of the EyeAnatomy of the Eye• Eyebrows shade eyes from light, particles and sweat• Eyelashes catch debris, keep eyes moist, shade the
eyes• Orbit: bony socket that holds the eye• Eye position: 100 degrees peripheral vision• Eyelids:
• Four layers (outer skin, muscles, connective tissue, conjunctiva)
• Layers allow the eyes to open and close
Anatomy of the Eye Anatomy of the Eye (Continued)(Continued)
• Conjunctiva: thin transparent layer, mucous membrane, covers eyelids and sclera
• Lacrimal gland: in orbit, secretes tear into eye; has ducts to nasal cavity
Anatomy of the Eye Anatomy of the Eye (Continued)(Continued)
• Cornea: transparent cover allows light into the eye• Connective tissue covered with thin epithelial
layer• No blood vessels—nourished by aqueous
humor (tissue fluid) and oxygen• Nerve fibers sensitive to pain
Anatomy of the Eye Anatomy of the Eye (Continued)(Continued)• Sclera:
• Attached to cornea; wraps around back of eyeball
• White portion of eye: many fibers and muscles with opening for optic nerve
• Optic nerve sends images to brain for interpretation
• Iris: colored part of eye to filter light
• Vitreous humor: nourishes and cleanses eye
Anatomy of the Eye Anatomy of the Eye (Continued)(Continued)
Eye Muscles and Direction of MovementEye Muscles and Direction of Movement
• Six muscles responsible for eye movements
Anatomy of the Eye Anatomy of the Eye (Continued)(Continued)
• Pupil:• Dilates (mydriasis) when focusing on distant figure
or darkness• Constricts (miosis) in extreme light
• Aqueous humor • provides the nutrients and oxygen to maintain lens
and cornea• Accumulates; must be released to maintain pressure• Canal of Schlemm: ducts used to release aqueous
humor
Anatomy of the Eye Anatomy of the Eye (Continued)(Continued)
• Retina contains rods and cones responsible for vision
• Rods: sight in dim light; produce black and white images
• Cones: detect color• Rods and cones signals sent
through optic nerve to brain• Occipital lobe—visual
interpretation How the Eye Works - Video clip
Rods and ConesRods and Cones
Conditions That Affect the EyeConditions That Affect the Eye• New developments/treatments:
• Laser surgery-correct vision• Lens implantation—for blindness
• Conditions: • Glaucoma• Conjunctivitis• Congestion of eye• Viral and bacterial infections
GlaucomaGlaucoma
• Pressure within the eyes is higher than normal (increased ocular pressure [IOP])
• Two causes: overproduction of aqueous humor; blocked ducts that drain excess aqueous humor
• Left untreated, causes blindness
• Types of glaucoma include primary, acute congestive, and chronic simple
GlaucomaGlaucoma
ConjunctivitisConjunctivitis
• “Pink eye”
• Common in daycare centers; contagious
• Acute inflammation of the conjunctiva
• Causes: viral, bacterial, fungal, allergies
• Symptoms: inflammation, itching, burning, white mucus
ConjuctivitisConjuctivitis
Color BlindnessColor Blindness
• Cones: responsible for color perception
• Three photopigments—identifies three colors—green, blue, red
• Missing/abnormal pigment: difficult or impossible to detect colors
• No treatment available
Color Blindness TestsColor Blindness Tests
BlindnessBlindness
• Causes:• Accidents• Cataracts• Macular Degeneration• Diabetic Retinopathy• Glaucoma
• Corneal transplant—may correct blindness
Ophthalmic AgentsOphthalmic Agents• Ophthalmic agents aimed at
controlling glaucoma, infection, inflammation, or manipulating dilation
• Dosage forms: drops, suspensions, ointments, medicated disks, corrective lenses
General InformationGeneral Information• Eye solutions—keep sterile—
foreign objects instilled into eyes can cause damage or infection
• Patients avoid touching medication; will cause contamination
• Do not instill while wearing contact lenses
The EarThe Ear• Human ear responsible for
hearing, balance, equilibrium, communication skills
• Composed of three sections: external, middle, inner
The EarThe Ear
External EarExternal Ear• External ear—auricle; composed of
cartilage and skin; entrance for sound waves
• Auditory canal: about 1 inch long; leads to tympanic membrane (eardrum)
• Two major functions of tympanic membrane: protection of middle ear from foreign objects; transmission of sounds to middle ear
External EarExternal Ear• Sounds transmitted by vibrations
• Cerumen: wax substance produced by glands
Middle EarMiddle Ear• Vibration carried to
middle ear
• Cavity contains bony structures (ossicles): malleus, incus, stapes
• Ossicles connected to each other
Middle EarMiddle Ear
• Eustachian tube:
• Leads to nasopharynx
• Equalizes pressure between outside and inside atmosphere
Eustachian TubeEustachian Tube
Inner EarInner Ear• Stapes continues transfer of sound to inner
ear
• Fluid-filled cavity—labyrinth; comprise many components that process and transmit audible sounds via nerve impulses to brain
Inner Ear Inner Ear (Continued)(Continued)
• Three main areas of the inner ear include:• Cochlea• Vestibule• Semicircular canal
How the Ear works Video
Conditions Affecting the EarConditions Affecting the Ear• Various conditions affect quality of hearing:
infections, ear wax accumulation, damage to eardrum, genetic defects
• Deafness—factors other than genetic abnormalities—age, inflicted damage
• Loud noises break hairlike structures in middle ear; do not regenerate
• No medication available—hearing aids
Otitis MediaOtitis Media
• Infection of the middle ear associated with inflammation of eustachian tube
• Sore throat—can lead to middle ear infection—often seen in children
• Treatment: antiinfectives
• Reoccurring infections—insertion of small tubes by physicians to drain middle ear
Cerumen Buildup and OtotoxicityCerumen Buildup and Ototoxicity
• Excessive wax builds up or dries—impedes hearing quality
• Doctor removes wax buildup
• Ototoxicity caused by some drugs
• Tinnitus—buzzing or ringing in ears—if untreated leads to permanent ear damage
• Balance may also be affected
Otic PreparationsOtic Preparations
• Bacterial infections treated with bactericidal or bacteriostatic preparations
• All ear agents—combinations—antibiotics, steroids, ear wax removers