CHAPTER 31 Special Senses © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31-2 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 © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31-3 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 © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31-4 Learning Outcomes (cont.) 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 © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31-5 Learning Outcomes (cont.) 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 © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31-6 Learning Outcomes (cont.) 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 © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31-7 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 © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31-8 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 © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31-9 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 © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31-10 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 © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31-61 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 © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31-62 Apply Your Knowledge True or False: ANSWER: F An audiologist is a physician that specializes in ear health _ F Otitis media is also called swimmers’ ear _ otologist externa T Presbycusis is hearing loss due to the aging process _ F Vertigo is ringing in the ears _ Tinnitus T Otitis interna is an inflammation of the labyrinth _ T Ménière's disease is characterized by disturbances in equilibrium _ T Otosclerosis is the immobilization of the stapes _ F Tinnitus is dizziness _ Vertigo © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31-63 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 © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31-64 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 © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31-65 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 © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31-66 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 © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31-67 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 © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31-68 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 © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31-69 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 © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31-70 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 © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31-71 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 © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31-72 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 © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31-73 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 © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31-74 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 © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31-75 End of Chapter 31 Every closed eye is not sleeping, and every open eye is not seeing ~ Bill Cosby © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed [...]... ed 31- 33 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 © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31- 34 Vision Screening Tests • Myopia – impairment of distance vision – Eyeball is too long – Light... 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 © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31- 18 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... Sight (cont.) • 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 © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31- 22 Eye and Sense of Sight (cont.)... panie s, Inc A ll rights reserv ed 31- 14 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” Tongu e © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31- 15 Back © 2011 T he McGraw -Hill Com... chambers – Specialized parts © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31- 19 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 © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31- 20 Eye and Sense of Sight (cont.) • Middle –. .. 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 © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31- 35 Vision Screening Tests (cont.) • Contrast sensitivity – Distinguish... 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 © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31- 25 Visual Accessory Organs (cont.) • Conjunctivas – Mucous membranes – Line inner surfaces of eyelids... receptors – located on taste buds • Taste buds – Location • Papillae of the tongue • Roof of mouth } fewer than on tongue • Walls of throat Tongu e © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31- 13 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... • 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 © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31- 23 Back © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31- 24 Visual Accessory... 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 © 2011 T he McGraw -Hill Com panie s, Inc A ll rights reserv ed 31- 21 Eye and Sense of Sight