Y khoa, dược - Special senses

31Special Senses31-2Learning Outcomes31.1 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.31-3Learning 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. 31-4Learning 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.31-5Learning 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.31-6Learning 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.31-7Introduction Special sensesSensory receptors located in headNose – smell Tongue – tasteEyes – vision Ears – hearing and equilibrium Touch is a generalized sense Stimulus  nervous system  brain  response31-8Nose and Sense of SmellOlfactory receptorsChemoreceptors – respond to changes in chemical concentrationsChemicals must be dissolved in mucusLocated in the olfactory organ31-9Smell Sensationthat send the information along olfactory bulbs and tracts to different areas of the cerebrum; cerebrum interprets the information as a particular type of smell Activation of smell receptors  information sent to olfactory nerves31-10Nose and Sense of Smell (cont.)Sensory AdaptationChemical can stimulate receptors for limited timeReceptors fatigue and stop responding to chemicalNo longer smell odor31-11Apply Your KnowledgeANSWER: 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. You notice an odor coming from a patient when you enter the exam room. Why would the patient not be able to smell it?Very Good!31-12Tongue and Sense of TasteGustatory receptors – located on taste budsTaste budsLocationPapillae of the tongueRoof of mouthWalls of throatTongue} fewer than on tongue 31-13Tongue and Sense of Taste (cont.)Taste cells and supporting structuresOn taste budsSupporting structures fill in spaceTaste cells ChemoreceptorsChemicals in food and drink must be dissolved in saliva to activate Tongue31-14Tongue and Sense of Taste (cont.)Taste sensation 4 primary Sweet – tip Sour – sides Salty – tip and sidesBitter – back Umami 5th basic taste Glutamic acidSpicy foodsActivate pain receptorsInterpreted by brain as “spicy”Tongue31-15Back31-16Tongue and Sense of Taste (cont.)Activation of taste cellsCranial nervesGustatory cortex of cerebruminterprets informationTaste sensation31-17Apply Your KnowledgeWhat 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 tongueSour – concentrated on the sides of the tongueSalty – concentrated on the tip and sides of the tongueBitter – concentrated on the back of the tongueGreat Job!31-18Eye and Sense of SightVision systemEyesOptic nervesVision centers in the brainAccessory structuresEye Processes light to produce imagesThree layersTwo chambersSpecialized parts31-19Eye and Sense of Sight (cont.)Outer – sclera White of the eye Protects the eyeSense receptorsCornea Front of eye “Window” that allows light into eyeBends light as it enters Eye31-20Eye and Sense of Sight (cont.)Middle – choroid Contains blood vesselsIrisColored part of eyeMuscle that contracts and relaxes to open or close pupilRegulates the amount of light that enters the eyeCiliary bodyMuscles Controls the shape of the lensLens Posterior to irisFocuses light on retinaAccommodationEye31-21Eye and Sense of Sight (cont.)Inner – retinaVisual receptorsRods Sensitive to light Will function in dim light – “limited” night visionDo not provide sharp image or detect colorConesFunction in bright lightSensitive to color and provide sharp imagesOptic disc – optic nerve enters retinaEye31-22Eye and Sense of Sight (cont.)Chambers of the eyeAnterior chamberFront of lensFilled with aqueous humor – nourishes and bathes anterior eyePosterior chamberBehind lensContains vitreous humor – maintains shape of eyeball and holds retina in placeEye31-23Back31-24Visual Accessory OrgansEye orbitsEye sockets Form a protective shell around the eyesEyebrows protect eyesEyelids Skin, muscle, and connective tissueBlinking Prevents surface from drying outKeeps foreign material out of eye31-25Visual Accessory Organs (cont.)Conjunctivas Mucous membranes Line inner surfaces of eyelidsLacrimal apparatusLacrimal glandsLateral edge of eyeballsProduce tearsNasolacrimal ductsMedial aspect of eyeballsDrain tears into nose31-26Visual Accessory Organs (cont.)Extrinsic eye musclesSix per eye move the eyeballSuperiorlyInferiorlyLaterally Medially 31-27OpticchiasmVisual PathwaysEye works like a cameraLight enters the eye through the lensRefraction – cornea, lens, and fluids bend light to focus it on the retinaOpticnerveOccipital lobe ofcerebrumRetina convertslight to nerve impulseImage upside down on retinaImage turned right-side up31-28Eye Safety and Protection90% of eye injuries are preventableEye safety practicesAdequate lighting/handrailsPad or cushion sharp edges on furnitureToys should be age-appropriateDo not mix chemicalsProper protective wearGogglesSports eye guards31-29Apply Your KnowledgeMatching:___ 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. RefractionIHFEDCBAGANSWER:Out of Sight!31-30The Aging EyeEyelids may droop Quality and quantity of tears decreaseConjunctiva thins and eyes may become dryerCornea yellows, fat deposits around itBrown spots on scleraPupils become smallerLens denser and more rigidLens yellowsRetinal changes – vision fuzzyChanges in ability of eye to adapt to lightImpaired night visionDecreased peripheral vision; depth perceptionFloaters or flashes of light31-31Preventing Falls in the ElderlyFalls can result in fractures of major bonesComplications of falls can lead to deathProne to falling Vision problemsPoor healthSlower reflexesPatient educationSafety checklistPrecautionsEquilibrium problemsMedication31-32Apply Your KnowledgeWhat 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!31-33Vision TestingProfessionals includeOphthalmologist – medical doctor who is an eye specialistOptometrist – provides vision screening and diagnostic testingOpticians – fills vision prescriptions for glasses and contacts31-34Vision Screening TestsMyopia – impairment of distance visionEyeball is too long Light focuses anterior to retinaSnellen chartNormal vision 20/20Hyperopia – impairment of near vision Eyeball is shorter Light focused posterior to retinaTest using a handheld chart with various sizes of printPresbyopia Impairment due to agingLoss of lens elasticity31-35Vision Screening Tests (cont.)Contrast sensitivityDistinguish shades of grayTestingPelli-Robson contrast sensitivity chartVistech Consultants vision contrast systemDetect cataracts or retinal problems before sharpness is impairedColor vision Color-blindness May be inheritedMore common in malesTestsIshihara color systemRichmond pseudoisochromatic color testDifficulties may indicate retinal or optic nerve disease31-36Apply Your KnowledgeWhat 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!31-37Treating Eye ProblemsDelicate organ – caution and sterile technique necessaryPatient education on preventive careAdministration of medicationsOnly ophthalmic medicationsAvoid touching dropper or ointment tube to the eyeEye irrigation Sterile solutionPurposeRemove foreign materialRelieve discomfort31-38Common Diseases and DisordersDisorder/DiseaseDescription AmblyopiaLazy eye; one eye is not used regularly; poor depth perception; often concurrent with strabismusAstigmatismCornea or lens has abnormal shape; blurred images CataractsOpaque structures in lens prevent light from passing through; vision fuzzyConjunctivitisPink eye; highly contagious bacterial infection31-39Common Diseases and Disorders (cont.)Disorder/DiseaseDescription Dry eye syndromeCommon problem; decreased production of oil in tearsEntropionInversion of lower eyelidGlaucomaIncrease in intraocular pressure due to a buildup of aqueous humor in anterior chamberHyperopiaFarsightedness31-40Common Diseases and Disorders (cont.)Disorder/DiseaseDescription Macular degenerationProgressive disease; inadequate blood supply to retina; most common cause of vision loss; affects people over 50 yearsMyopiaNearsightednessNystagmusRapid, involuntary eye movements31-41Common Diseases and Disorders (cont.)Disorder/DiseaseDescription PresbyopiaLoss of lens elasticity; develops with ageRetinal detachmentLayers of retina separate; medical emergencyStrabismus Convergent DivergentMisalignment of eyesCrossed eyes; one or both eyes turn inwardWall eye; one or both eyes turn outward31-42Apply Your KnowledgeIt 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!31-43The EarExternal earAuricle (pinna)Collects sound wavesExternal auditory canalGuides sound wave to tympanic membraneTympanic membraneSeparates external canal and middle earVibrates when sound hits itEar31-44The Ear (cont.)Eustachian tubeConnects middle ear to throatEqualizes pressure on eardrumOval windowSeparates middle ear from inner earEarMiddle earEar ossiclesMalleusIncusStapesOssicles vibrate in response to vibration of tympanic membrane31-45The Ear (cont.)Inner ear – labyrinth of communicating chambersSemicircular canals – detect balance of the bodyVestibule – equilibrium Cochlea Hearing receptorsOrgan of Corti – organ of hearingEar31-46Back Back 31-47EquilibriumHead movement causes fluid in semicircular canals and vestibule to moveEquilibrium receptors transmit information along vestibular nerves to cerebrum Cerebrum determines if body needs to make adjustments31-48Sense of HearingSound waves collectedWaves cause tympanic membrane to vibrate Ossicles amplify vibrations, which enter inner earMovement of hairs lining cochlea trigger nerve impulsesImpulses are transmitted by auditory nerve to the brain for interpretation31-49Sense of Hearing (cont.)Bone conductionAlternative pathwayBypasses external and middle ear directly to innerUseful in determining cause of hearing problem31-50Apply Your KnowledgeMatching: ___ 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 canalsHGFDCBAEANSWER:Supear!31-51How to Recognize Hearing Problems in ChildrenGuidelines Infants to 4 monthsStartled by loud noisesRecognize mother’s voice4 to 8 monthsRegularly follow soundsBabble at people8 to 12 monthsRespond to the sound of their nameRespond to “no”31-52The Aging EarExternal ear larger / earlobe longerCerumen dryer and prone to impactionEar canal narrowerEardrum shrinks and appears dull and grayOssicles do not move as freelySemicircular canals less sensitive to changes in position – affects balance 31-53Apply Your KnowledgeWhat 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!31-54Hearing LossSymptom of a disease, not a normal part of agingConductive hearing lossInterruption in transmission to inner earCauses Obstruction of ear canalInfection of middle earReduced movement of stirrupSensorineural hearing lossSound waves not perceived by brain as soundCauses HereditaryRepeated exposure to loud noises/viral infectionsSide effect of medication31-55Hearing Loss (cont.)Noise pollution – causes damage to sensitive cells in cochleaWorking with the hearing-impaired patientSpeak at a reasonable volume, in clear, low-pitched volumesFace the person; use hand gestures, if appropriate Do not overemphasize lip movementsHave patient repeat message to verify understandingTreat hearing-impaired patients with patience and respect31-56Hearing and Diagnostic TestsHearing testsTuning forks – differentiate between types of lossAudiometer – measures hearing acuityDiagnostic testingTympanometry Measures the ability of the eardrums to move Detects diseases and abnormalities of the middle ear31-57Apply Your Knowledge Identify the types of hearing loss based on the description below. What can be used to differentiate between the two?Sound waves not perceived by brain as soundCauses HereditaryRepeated exposure to loud noises/viral infectionsSide effect of medicationInterruption in transmission to inner earCauses Obstruction of ear canalInfection of middle earReduced movement of stirrupAnswer: Conductive hearing loss Sensorineural hearing lossBravo!A tuning fork is a simple test to distinguish between types of hearing loss. 31-58Treating Ear and Hearing ProblemsPatient education Preventative ear careAdminister ear medicationsMedications and irrigationRelieve inflammation or irritation of canalLoosen and remove impacted cerumen or foreign body31-59Treating Ear and Hearing Problems (cont.)Hearing aidsObtaining a hearing aidOtologist – medical doctor specializing in health of earAudiologist – evaluates and corrects hearing problemsCare and useBatteries Routine cleaningKeep dry and avoid hair spraysOther devices / strategiesAmplifiers Closed-captioningAppliances that light up as well as ring31-60Common Diseases and DisordersDisorder/DiseaseDescriptionCerumen impactionBuild up of wax within external auditory canalHearing lossDeafness Ménière's diseaseDisturbance in equilibrium characterized by vertigo and tinnitus31-61Common Diseases and DisordersDisorder/DiseaseDescriptionOtitis Otitis externa Otitis media Otitis internaInflammation of the ear Swimmers’ earMiddle ear infection; common infectionLabyrinthitis; inner ear infectionOsteosclerosisImmobilization of the stapes; common cause of conductive hearing lossPresbycusisHearing loss due to aging process31-62Apply Your KnowledgeTrue 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.FFFTTTTFANSWER:otologist externaTinnitus VertigoExcellent!31-63In Summary31.1 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.31-64In 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.31-65In 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.31-66In 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.31-67In 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. 31-68In 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.31-69In 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.31-70In 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.31-71In 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.31-72In 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.31-73In 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.31-74In 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. 31-75Every closed eye is not sleeping, and every open eye is not seeing. ~ Bill CosbyEnd of Chapter 31