31 Special Senses.

31 Special Senses

Learning Outcomes 31.1 Describe the anatomy of the nose and the function of each part. 31.2 Describe how smell sensations are created and interpreted. 31.3 Describe the anatomy of the tongue and the function of each part. 31.4 Describe how taste sensations are created and interpreted.

Learning Outcomes (cont.)
31.5 Name the four primary taste sensations and the acknowledged fifth taste sensation. 31.6 Describe the anatomy of the eye and the function of each part, including the accessory structures and their functions. 31.7 Trace the visual pathway through the eye and to the brain for interpretation. 31.8 Identify ways that patients can practice preventive eye care.

31.9 State ways that vision changes with age. 31.10 List the medical professionals involved in diagnosis and treatment of visual disorders, including the roles that each play in patient care. 31.11 List treatments for visual disorders. 31.12 Describe the causes, signs and symptoms, and treatments of various diseases and conditions of the eye.

31.13 Describe the anatomy of the ear and the function of each part. 31.14 Explain the role of the ear in maintaining equilibrium. 31.15 Explain how sounds travel through the ear and are interpreted in the brain. 31.16 State ways that hearing changes with age.

31.17 List the types of hearing loss and how they differ. 31.18 Describe treatments for ear and hearing disorders. 31.19 Explain how patients can be educated about preventive ear care. 31.20 Describe the causes, signs and symptoms, and treatments of various disorders of the ear and hearing.

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

Smell Sensation Activation of smell receptors 
information sent to olfactory nerves that send the information along olfactory bulbs and tracts to different areas of the cerebrum; cerebrum interprets the information as a particular type of smell

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 odor

Very Good! Apply Your Knowledge
You notice an odor coming from a patient when you enter the exam room. Why would the patient not be able to smell it? ANSWER: After a few minutes, smell receptors undergo sensory adaptation and no longer respond to the chemical, and the patient can no longer smell the odor. Very Good!

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 Tongue

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

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” Tongue

Taste sensation Activation of taste cells Cranial nerves Gustatory cortex of cerebrum interprets information

Apply Your Knowledge Great Job!
What are the four primary taste sensations and where are their corresponding taste cells located? ANSWER: The four primary taste sensations are: Sweet – concentrated on the tip of the tongue Sour – concentrated on the sides of the tongue Salty – concentrated on the tip and sides of the tongue Bitter – concentrated on the back of the tongue Great Job!

Eye and Sense of Sight Vision system Eye Eyes Optic nerves
Vision centers in the brain Accessory structures Eye Processes light to produce images Three layers Two chambers Specialized parts

Eye and Sense of Sight (cont.)
Outer – sclera White of the eye Protects the eye Sense receptors Cornea Front of eye “Window” that allows light into eye Bends light as it enters Eye

Middle – choroid Contains blood vessels Iris Colored part of eye Muscle that contracts and relaxes to open or close pupil Regulates the amount of light that enters the eye Ciliary body Muscles Controls the shape of the lens Lens Posterior to iris Focuses light on retina Accommodation Eye

Inner – retina Visual receptors Rods Sensitive to light Will function in dim light – “limited” night vision Do not provide sharp image or detect color Cones Function in bright light Sensitive to color and provide sharp images Optic disc – optic nerve enters retina Eye

Chambers of the eye Anterior chamber Front of lens Filled with aqueous humor – nourishes and bathes anterior eye Posterior chamber Behind lens Contains vitreous humor – maintains shape of eyeball and holds retina in place Eye

Visual Accessory Organs
Eye orbits Eye sockets Form a protective shell around the eyes Eyebrows protect eyes Eyelids Skin, muscle, and connective tissue Blinking Prevents surface from drying out Keeps foreign material out of eye

Visual Accessory Organs (cont.)
Conjunctivas Mucous membranes Line inner surfaces of eyelids Lacrimal apparatus Lacrimal glands Lateral edge of eyeballs Produce tears Nasolacrimal ducts Medial aspect of eyeballs Drain tears into nose

Visual Accessory Organs (cont.)
Extrinsic eye muscles Six per eye move the eyeball Superiorly Inferiorly Laterally Medially

Visual Pathways Eye works like a camera
Light enters the eye through the lens Refraction – cornea, lens, and fluids bend light to focus it on the retina Optic chiasm Image upside down on retina Image turned right-side up Occipital lobe of cerebrum Retina converts light to nerve impulse Optic nerve

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

Out of Sight! Apply Your Knowledge ANSWER: Matching:
___ Middle layer of eye A. Lacrimal glands ___ Eye sockets B. Aqueous humor ___ Control shape of lens C. Retina ___ Outer layer of eye D. Sclera ___ Anterior chamber E. Vitreous humor ___ Tears F. Ciliary body ___ Bending of light G. Choroid ___ Posterior chamber H. Orbits ___ Inner layer of eye I. Refraction H F D B A I Out of Sight! E C

The Aging Eye Eyelids may droop Quality and quantity of tears decrease
Conjunctiva thins and eyes may become dryer Cornea yellows, fat deposits around it Brown spots on sclera Pupils become smaller Lens denser and more rigid Lens yellows Retinal changes – vision fuzzy Changes in ability of eye to adapt to light Impaired night vision Decreased peripheral vision; depth perception Floaters or flashes of light

Preventing Falls in the Elderly
Falls can result in fractures of major bones Complications of falls can lead to death Prone to falling Vision problems Poor health Slower reflexes Patient education Safety checklist Precautions Equilibrium problems Medication

Nice job! Apply Your Knowledge
What vision changes can occur in the elderly patient? ANSWER: An elderly patient may have difficulty seeing because of drooping eyelids. Focusing may be more difficult because less light enters the eye. He may have difficulty distinguishing colors due to yellowing of the lens. Vision may be fuzzy because of changes in the retina. Night vision can become impaired. The patient may see floaters or “sparks.” Nice job!

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

Vision 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

Vision Screening Tests (cont.)
Contrast sensitivity Distinguish shades of gray Testing Pelli-Robson 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

Reyeght! Apply Your Knowledge
What is the difference between myopia and hyperopia and what is presbyopia? What effect does each have on vision? ANSWER: If the patient has myopia, the eyeball is elongated and light focuses in front of the retina. She will have difficulty seeing far away. If she has hyperopia, the eyeball is shorter than normal and light focuses behind the retina. With presbyopia, the lens loses elasticity due to aging, resulting in the inability to see things close up. Reyeght!

Treating Eye Problems Delicate organ – caution and sterile technique necessary Patient education on preventive care Administration of medications Only ophthalmic medications Avoid touching dropper or ointment tube to the eye Eye irrigation Sterile solution Purpose Remove foreign material Relieve discomfort

Common Diseases and Disorders
Disorder/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

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

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

Disorder/Disease Description Presbyopia 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

Apply Your Knowledge Correct!
It is okay to use any solution or medication in the eye? ANSWER: Only medications or solutions specifically designated for ophthalmic use may be used in the eyes. Medications not designated for the eye may be too concentrated or contain substances that can injure the eye. Solutions should be sterile and care must be taken not to contaminate the tip of the dropper or bottle. Correct!

The Ear External ear Auricle (pinna) External auditory canal
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

The Ear (cont.) Middle ear Eustachian tube Ear ossicles Oval window
Connects middle ear to throat Equalizes pressure on eardrum Oval window Separates middle ear from inner ear Middle ear Ear ossicles Malleus Incus Stapes Ossicles vibrate in response to vibration of tympanic membrane Ear

The Ear (cont.) Inner ear – labyrinth of communicating chambers
Semicircular canals – detect balance of the body Vestibule – equilibrium Cochlea Hearing receptors Organ of Corti – organ of hearing Ear

Back Back

Equilibrium Head movement causes fluid in semicircular canals and vestibule to move Equilibrium receptors transmit information along vestibular nerves to cerebrum Cerebrum determines if body needs to make adjustments

Sense of Hearing Sound waves collected
Waves cause tympanic membrane to vibrate Ossicles amplify vibrations, which enter inner ear Movement of hairs lining cochlea trigger nerve impulses Impulses are transmitted by auditory nerve to the brain for interpretation

Sense of Hearing (cont.)
Bone conduction Alternative pathway Bypasses external and middle ear directly to inner Useful in determining cause of hearing problem

Apply Your Knowledge Supear! ANSWER: Matching:
___ Pinna A. Organ of Corti ___ Malleus, incus, and stapes B. Cerumen ___ Hearing receptors C. Ear ossicles ___ Inner ear D. Tympanic membrane ___ Organ of hearing E. Auricle ___ Earwax F. Cochlea ___ Eardrum G. Labyrinth ___ Detect balance of body H. Semicircular canals C F G A B D H

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 of their name Respond to “no”

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

Apply Your Knowledge What problem with the aging ear makes the elderly more prone to falls? ANSWER: The semicircular canals become less sensitive to change in position, which affects balance. This problem with equilibrium results in increased chance of falls in the elderly. Great Answer!

Hearing Loss Symptom of a disease, not a normal part of aging
Conductive hearing loss Interruption in transmission to inner ear Causes Obstruction of ear canal Infection of middle ear Reduced movement of stirrup Sensorineural hearing loss Sound waves not perceived by brain as sound Causes Hereditary Repeated exposure to loud noises/viral infections Side effect of medication

Hearing Loss (cont.) Noise pollution – causes damage to sensitive cells in cochlea Working with the hearing-impaired patient Speak at a reasonable volume, in clear, low-pitched volumes Face the person; use hand gestures, if appropriate Do not overemphasize lip movements Have patient repeat message to verify understanding Treat hearing-impaired patients with patience and respect

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

Bravo! Apply Your Knowledge
Identify the types of hearing loss based on the description below. What can be used to differentiate between the two? Answer: Conductive hearing loss Sensorineural hearing loss A tuning fork is a simple test to distinguish between types of hearing loss. Sound waves not perceived by brain as sound Causes Hereditary Repeated exposure to loud noises/viral infections Side effect of medication Interruption in transmission to inner ear Obstruction of ear canal Infection of middle ear Reduced movement of stirrup Bravo!

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

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

Disorder/Disease Description Cerumen impaction Build up of wax within external auditory canal Hearing loss Deafness Ménière's disease Disturbance in equilibrium characterized by vertigo and tinnitus

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

Apply Your Knowledge Excellent! ANSWER: True or False:
___ An audiologist is a physician that specializes in ear health. ___ Otitis media is also called swimmers’ ear. ___ Presbycusis is hearing loss due to the aging process. ___ Vertigo is ringing in the ears. ___ Otitis interna is an inflammation of the labyrinth. ___ Ménière's disease is characterized by disturbances in equilibrium. ___ Otosclerosis is the immobilization of the stapes. ___ Tinnitus is dizziness. F otologist F externa T F Tinnitus Excellent! T T T F Vertigo

In Summary 31.1 Olfactory receptors, which are the sense receptors for the sense of smell, are found in the olfactory organ located in the upper part of the nasal cavity. 31.2 When the olfactory receptors are activated, they send information to the olfactory nerves, then on to the cerebellum for interpretation. 31.3 Gustatory receptors are found on the taste buds, which are located on the papillae (bumps) of the tongue.

In Summary (cont.) 31.4 Gustatory receptors are chemoreceptors which are activated by the chemicals found in food and drink as they are dissolved in the mouth’s saliva. The information is brought to the gustatory cortex of the parietal lobe of the brain for interpretation. 31.5 The four primary taste sensations are, sweet, salty, sour and bitter. Each has a “specialized” area of the tongue where each taste is most pronounced. The fifth recognized taste sensation is umami.

In Summary (cont.) 31.6 The eye is composed of three layers. The sclera is the outer protective layer and includes the cornea. The middle vascular layer is the choroid, consisting of the iris, pupil, ciliary body, and lens, and is the area of light regulation and focusing. The innermost layer is the retina containing the rods and cones, the optic nerve, and optic disk. This is where the nerve impulse is picked up and brought to the brain for interpretation. The accessory organs are the orbits, eyelids, conjunctivas, lacrimal apparatus, and extrinsic eye muscles, all of which are protective for the eye.

In Summary (cont.) 31.7 The cornea, lens, and fluids focus light on the retina. The retina converts the image into nerve impulses, which are transmitted by the optic nerve to the brain for interpretation. 31.8 Eye safety and injury prevention includes, but is not limited to, adequate lighting and availability of hand rails, keeping personal and sharp items out of reach of children, wearing of safety goggles when operating power equipment and using chemicals, and not mixing cleaning agents.

In Summary (cont.) 31.9 Changes in the aging eye include, but are not limited to, diminishing fat tissue, decreased tear production, thinner and dryer conjunctiva, brown spots in the sclera, changes in the iris resulting in smaller pupil, lens becoming denser and more rigid, as well as lens and retinal changes causing fuzziness of vision and difficulty distinguishing colors. 31.10 Ophthalmologists (M.D.), optometrists (O.D.), and opticians are all professionals who deal with eye and vision health.

In Summary (cont.) 31.11 All treatments for eye problems include use of sterile technique and extreme caution to protect the delicate tissues of the eye. Eye irrigations and medication installations are common treatments. Instruction on these techniques will take place in the Drug Administration chapter.

In Summary (cont.) 31.12 Common diseases and disorders of the eye include amblyopia, astigmatism, cataracts, conjunctivitis, hyperopia, myopia and presbyopia. More detailed information on the signs, symptoms, and treatments for these conditions, as well as other common eye disorders, is found in the Pathophysiology section of this chapter, directly after the A&P section on the eye.

In Summary (cont.) 31.13 There are three parts to the ear. The external ear includes the auricle or pinna and external auditory canal to the tympanic membrane. The middle ear begins at the tympanic membrane and ends at the oval window and includes the ear ossicles. The inner ear is composed of the labyrinth and contains the organ of Corti as well as perilymph and endolymph, the fluids of hearing. 31.14 The semicircular canals and vestibule in the inner ear function in the equilibrium and balance of the body, sending impulses to the vestibular nerves, which transmit information to the cerebrum for interpretation.

In Summary (cont.) 31.15 The outer ear collects sound waves and channels them to the tympanic membrane, which vibrates. The vibrations are amplified by the ear ossicles and enter the inner ear and cochlea. The movements of the hairs in the cochlea trigger nerve impulses that are transmitted by the auditory nerve to the brain. 31.16 Aging causes the eardrum to shrink. The joints between the ossicles degenerate so there is less freedom of movement, which causes decrease in hearing acuity.

In Summary (cont.) 31.17 Conductive hearing loss is the result of sound wave transmission interruption, as with cerumen impaction and tumors or infections. Sensorineural hearing loss is the result of nerve damage so that the brain cannot perceive sounds waves as sound. 31.18 Ear treatments depend on the condition being treated, but may include ear irrigation and medication installation as well as hearing aids and/or surgery for hearing loss.

In Summary (cont.) 31.19 Preventative ear care includes, but is not limited to, routine hearing exams; avoiding the insertion of small items into the ear canal; and using care when using cotton swabs. Ear protection should be used when exposed to loud or prolonged noise. Use medications such as ear drops properly and watch for signs of ear or hearing problems.

In Summary (cont.) 31.20 The pathophysiology section on ear and hearing diseases and conditions is found at the end of the A&P section for the ear. Signs, symptoms, and treatments of cerumen impaction, hearing loss, Ménière's disease, otitis, otosclerosis, and other common problems are outlined in this section.

End of Chapter 31 Every closed eye is not sleeping, and every open eye is not seeing. ~ Bill Cosby

31 Special Senses.

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