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!