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The special senses are smell, taste, vision, hearing, and equilibrium. They are called special senses because their sensory receptors are located within relatively large sensory organs in the head - the nose, tongue, eyes, and ears. Chapter 31 - Special senses, this chapter introduces the structure and function of these sense organs and focuses on common diseases of the eyes and ears.
CHAPTER 31 Special Senses © 2011 The McGraw-Hill Companies, Inc All rights reserved 312 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 The McGraw-Hill Companies, Inc All rights reserved 313 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 The McGraw-Hill Companies, Inc All rights reserved 314 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 The McGraw-Hill Companies, Inc All rights reserved 315 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 The McGraw-Hill Companies, Inc All rights reserved 316 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 The McGraw-Hill Companies, Inc All rights reserved 317 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 The McGraw-Hill Companies, Inc All rights reserved 318 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 The McGraw-Hill Companies, Inc All rights reserved 319 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 The McGraw-Hill Companies, Inc All rights reserved 3110 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 The McGraw-Hill Companies, Inc All rights reserved 3161 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 The McGraw-Hill Companies, Inc All rights reserved 3162 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 The McGraw-Hill Companies, Inc All rights reserved 3163 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 The McGraw-Hill Companies, Inc All rights reserved 3164 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 The McGraw-Hill Companies, Inc All rights reserved 3165 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 The McGraw-Hill Companies, Inc All rights reserved 3166 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 The McGraw-Hill Companies, Inc All rights reserved 3167 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 The McGraw-Hill Companies, Inc All rights reserved 3168 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 The McGraw-Hill Companies, Inc All rights reserved 3169 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 The McGraw-Hill Companies, Inc All rights reserved 3170 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 The McGraw-Hill Companies, Inc All rights reserved 3171 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 The McGraw-Hill Companies, Inc All rights reserved 3172 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 The McGraw-Hill Companies, Inc All rights reserved 3173 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 The McGraw-Hill Companies, Inc All rights reserved 3174 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 The McGraw-Hill Companies, Inc All rights reserved 3175 End of Chapter 31 Every closed eye is not sleeping, and every open eye is not seeing ~ Bill Cosby © 2011 The McGraw-Hill Companies, Inc All rights reserved ... rights reserved 31 14 Tongue and Sense of Taste (cont.) • Taste sensation – primary • Sweet – tip • Sour – sides • Salty – tip and sides • Bitter – back • Umami – 5th basic taste – Glutamic acid... reserved 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.. .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