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Special Senses
By Mr. Danilo Villar Rogayan Jr.
Instructor I, Department of Natural Sciences
College of Agriculture & Veterinary Medicine
RMTU San Marcelino
35-2
Introduction
• Special senses
• Sensory receptors located in head• Nose – smell
• Tongue – taste
• Eyes – vision
• Ears – hearing and equilibrium
• Touch is a generalized sense
• Stimulus nervous system brain response
Nose and Sense of Smell
• Olfactory receptors• Chemoreceptors –
respond to changes in chemical concentrations
• Chemicals must be dissolved in mucus
• Located in the olfactory organ
Nose and Sense of Smell (cont.)
• Sensory Adaptation• Chemical can stimulate receptors for limited
time
• Receptors fatigue and stop responding to chemical
• No longer smell order
Tongue and Sense of Taste
• Gustatory receptors – located on taste buds
• Taste buds• Location
• Papillae of the tongue
• Roof of mouth
• Walls of throat
} fewer than on
tongue
35-6
Tongue and Sense of Taste (cont.)
• Taste cells and supporting structures
• On taste buds
• Supporting structures fill in space
• Taste cells • Chemoreceptors
• Chemicals in food and drink must be dissolved in saliva to activate
Tongue
35-7
Tongue and Sense of Taste (cont.)
• Taste sensation • 4 primary
• Sweet – tip
• Sour – sides
• Salty – tip and sides
• Bitter – back
• Umami • 5th basic taste
• Glutamic acid
• Spicy foods• Activate pain
receptors
• Interpreted by brain as “spicy”
35-8
Back
35-9
Eye and Sense of Sight
• Vision system• Eyes
• Optic nerves
• Vision centers in the brain
• Accessory structures
• Eye • Processes light
to produce images
• Three layers
• Two chambers
• Specialized parts
35-10
35-11
Eye Safety and Protection
• 90% of eye injuries are preventable• Eye safety practices
• Adequate lighting / handrails• Pad or cushion sharp edges on furniture• Toys should be age-appropriate• Do not mix chemicals
• Proper protective wear• Goggles• Sports eye guards
35-12
Vision Testing
• Professionals include• Ophthalmologist – medical doctor who is an eye
specialist
• Optometrist – provides vision screening and diagnostic testing
• Opticians – fills vision prescriptions for glasses and contacts
35-13
Vision Testing: Screening Tests
• Myopia – impairment of distance vision
• Eyeball is too long
• Light focuses anterior to retina
• Snellen chart
• Normal vision • 20/20
• Hyperopia – impairment of near vision
• Eyeball is shorter
• Light focused posterior to retina
• Test using a handheld chart with various sizes of print
• Presbyopia• Impairment due to aging
• Loss of lens elasticity
35-14
• Contrast sensitivity
• Distinguish shades of gray
• Testing
• PelliRobson contrast
sensitivity chart
• Vistech Consultants vision
contrast system
• Detect cataracts or retinal
problems before sharpness
is impaired
• Color vision • Color-blindness
• May be inherited
• More common in males
• Tests• Ishihara color system
• Richmond pseudoisochromatic color test
• Difficulties may indicate retinal or optic nerve disease
Vision Testing: Screening Tests (cont.)
35-15
Treating Eye Problems
• Delicate organ – caution and sterile technique necessary
• Patient education on preventive care
• Administration of medications
• Only ophthalmicmedications
• Avoid touching dropper or ointment tube to the eye
• Eye irrigation • Sterile solution
• Purpose• Remove foreign
material
• Relieve discomfort
Common Diseases and DisordersDisorder / Disease Description
Amblyopia Lazy eye; one eye is not used regularly;
poor depth perception; often concurrent
with strabismus
Astigmatism Cornea or lens has abnormal shape;
blurred images
Cataracts Opaque structures in lens prevent light
from passing through; vision fuzzy
Conjunctivitis Pink eye; highly contagious bacterial
infection
35-17
Common Diseases and Disorders (cont.)
Disorder / Disease Description
Dry eye syndrome Common problem; decreased production
of oil in tears
Entropion Inversion of lower eyelid
Glaucoma Increase in intraocular pressure due to a
buildup of aqueous humor in anterior
chamber
Hyperopia Farsightedness
35-18
Common Diseases and Disorders (cont.)
Disorder / Disease Description
Macular
degeneration
Progressive disease; inadequate blood
supply to retina; most common cause of
vision loss; affects people over 50 years
Myopia Nearsightedness
Nystagmus Rapid, involuntary eye movements
35-19
Common Diseases and Disorders (cont.)
Disorder / Disease Description
Prespyopia Loss of lens elasticity; develops with age
Retinal
detachment
Layers of retina separate; medical
emergency
Strabismus
Convergent
Divergent
Misalignment of eyes
Crossed eyes; one or both eyes turn
inward
Wall eye; one or both eyes turn outward
35-20
The Ear and the Senses of Hearing and Equilibrium: Structures
• External ear• Auricle (pinna)
• Collects sound waves
• External auditory canal• Guides sound wave to tympanic membrane
• Tympanic membrane• Separates external canal and middle ear
• Vibrates when sound hits it
Ear
35-21
• Eustachian tube• Connects middle ear to
throat
• Equalizes pressure on eardrum
• Oval window• Separates middle ear
from inner ear
Ear
• Middle ear• Ear ossicles
• Malleus
• Incus
• Stapes
• Ossicles vibrate in response to vibration of tympanic membrane
The Ear and the Senses of Hearing and Equilibrium: Structures (cont.)
35-23
How to Recognize Hearing Problems in Children
• Guidelines • Infants to 4 months
• Startled by loud noises
• Recognize mother’s voice
• 4 to 8 months• Regularly follow sounds
• Babble at people
• 8 to 12 months• Respond to the sound their name
• Respond to “no”
35-24
The Aging Ear
• External ear larger / earlobe longer
• Cerumen dryer and prone to impaction
• Ear canal narrower
• Eardrum shrinks and appears dull and gray
• Ossicles do not move as freely
• Semicircular canals less sensitive to changes in position – affects balance
35-25
Hearing and Diagnostic Tests
• Hearing tests• Tuning forks – differentiate between types of loss
• Audiometer – measures hearing acuity
• Diagnostic testing• Tympanometry
• Measures the ability of the eardrums to move
• Detects diseases and abnormalities of the middle ear
35-26
Treating Ear and Hearing Problems
• Patient education • Preventative ear care
• Administer ear medications
• Medications and Irrigation• Relieve inflammation or irritation of canal
• Loosen and remove impacted cerumen or foreign body
35-27
Treating Ear and Hearing Problems (cont.)
• Hearing aids• Obtaining a hearing aid
• Otologist – medical doctor specializing in health of ear
• Audiologist – evaluates and corrects hearing problems
• Care and use
• Batteries
• Routine cleaning
• Keep dry and avoid hair sprays
• Other devices / strategies• Amplifiers
• Closed-captioning
• Appliances that light up as well as ring
35-28
Common Diseases and Disorders
Disorder /
Disease
Description
Cerumen
impaction
Build up of wax within external auditory
canal
Hearing loss Deafness
Meniere’s disease Disturbance in equilibrium characterized
by vertigo and tinnitus
35-29
Common Diseases and Disorders
Disorder /
Disease
Description
Otitis
Otitis externa
Otitis media
Otitis interna
Inflammation of the ear
Swimmers’ ear
Middle ear infection; common infection
Labyrinthitis; inner ear infection
Osteosclerosis Immobilization of the stapes; common
cause of conductive hearing loss
Presbycusis Hearing loss due to aging process
35-30
In Summary
• Special senses detect changes in the environment
• Each works with the nervous system to enable the body to cope with environmental changes
• Medical assistant’s knowledge of senses• Provide eye and ear care to patient
• Patient education
• Meet needs of children, elderly, and patients with impairments
35-31
Every closed eye is not sleeping, and
every open eye is not seeing.
~ Bill Cosby
Lakô hã salamát!Maraming salamat!
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