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Special Senses

Special Senses

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Special Senses

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  1. 31 Special Senses

  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.

  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.

  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.

  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.

  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.

  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

  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

  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

  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

  11. 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!

  12. Tongue 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

  13. 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

  14. 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 Tongue and Sense of Taste (cont.)

  15. Back

  16. Taste sensation Tongue and Sense of Taste (cont.) Activation of taste cells Cranial nerves Gustatory cortex of cerebruminterprets information

  17. Apply Your Knowledge 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!

  18. Vision system 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

  19. Eye 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

  20. 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 Eye and Sense of Sight (cont.)

  21. 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 Eye and Sense of Sight (cont.)

  22. Eye Eye and Sense of Sight (cont.) • 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

  23. Back

  24. 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

  25. 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.)

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

  27. Image upside down on retina Image turned right-side up Occipital lobe ofcerebrum Opticchiasm Opticnerve 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 Retina convertslight to nerve impulse

  28. 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

  29. 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 ANSWER: G Apply Your Knowledge H F D B A I Out of Sight! E C

  30. 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 The Aging Eye

  31. Equilibrium problems Medication 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

  32. 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!

  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

  34. 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

  35. 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 Vision Screening Tests (cont.)

  36. 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!

  37. Eye irrigation Sterile solution Purpose Remove foreign material Relieve discomfort 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

  38. Common Diseases and Disorders

  39. Common Diseases and Disorders (cont.)

  40. Common Diseases and Disorders (cont.)

  41. Common Diseases and Disorders (cont.)

  42. Apply Your Knowledge 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!

  43. Ear The Ear • 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

  44. Eustachian tube 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.)

  45. 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

  46. 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

  47. 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

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

  49. ANSWER: E Apply Your Knowledge Supear! 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

  50. 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” How to Recognize Hearing Problems in Children