1. SPECIAL SENSES

2. The Special Senses
Special Senses: Organs and sensory receptors associated with touch, vision, hearing, taste, and smell
Organs include – eyes, ears, nose, tongue, and sensory receptors of the skin

3. The Eye

4. 10 Facts about the Eye Video

5. Eye One inch in diameter sphere Protected by: Orbital socket /Skull
Eye lashes and brows
Lacrimal glands – produce tears which
moisten and cleanse the eye
Conjunctiva- mucous membrane which
lines eyes and covers front of eye to provide
protection and lubrication

6. 3 layers of eye
Sclera
Choroid coat
Retina

7. Anatomy of the Eye 3 Layers
1. Sclera: white of the eye
Maintains the shape of the eye
Extrinsic muscles - responsible for moving the eye within socket, are attached to outside of sclera

8. 3 layers of eye (cont’d)
2. Choroid layer
Middle layer of eye
Vascular

9. 3 layers of the eye (cont’d)
Retina – innermost layer of the eye
Many layers of nerve cells which transmit light impulses to optic nerve
2 types of special cells: rods and cones
Cones – sensitive to bright light and color - responsible for color vision
Rods – sensitive to dim light

10. Ophthalmoscope: used to examine retina

11. Fovea Centralis
Retina viewed through ophthalmoscope, dark disc is macula . Within macula is fovea centralis which contains cones for color vision.
Blind spot (optic disc) – contains no rods or cones therefore no visual reception

12. Optic Nerve
4. Optic Nerve - Cranial Nerve II = responsible for vision

13. Vitreous Humor
5. Vitreous humor – transparent, jellylike substance filling posterior chamber of eye
Helps maintain eyeball’s spherical shape

14. Lens 6. Lens- located behind pupil/iris.
Sits in between anterior and posterior chamber of eye
Function is to refract or bend light as it passes through – to focus images on the retina
Lens held in place by suspensory ligaments

15. Iris
7. Iris – colored muscular layer. Behind cornea and in front of choroid coat. Contains 2 muscles which control size of pupil and regulates amount of light entering eye
8. Intrinsic muscles – sphincter papillae (iris/pupil)
And suspensory ligaments and ciliary body (lens)

16. Pupil
9. Pupil – opening in center of iris. Light passes into eye through pupil

17. Aqueous Humor
10. Aqueous humor – water fluid in anterior chamber of eye

18. Cornea
11. Cornea – clear, circular area on front center of sclerotic coat
Has pain and touch receptors making it sensitive to foreign particles that come in contact with its surface

19. 12. suspensory ligaments – holds lens in place
13. ciliary bodies – smooth muscle controlling shape of lens

20. Conjunctiva
14. Conjunctiva – thin membrane lining the eyelids and covers part of the eye (anterior portion)
Secretes mucous to lubricate eye

21. Cow Eye Dissection
Exploratorium Cow Eye Dissection

22. Application Identify and describe your table partner’s:
pupil – how does the pupil react to light/dark
iris
sclera
upper lid
lower lid
conjunctiva
lacrimal duct (lacrimal canaliculus)

23. Review of Structures of Eye
Structures of Eye Video

24. Application: BS&F pg 180-181 Define the following vision disorders:
Presbyopia
Hyperopia
Myopia
Amblyopia
Astigmatism
Diplopia
Stabismus

25. Vision Disorders
Presbyopia – lens loses elasticity resulting in decreased ability to focus on close objects – usually onset at 40 yo
Hyperopia – farsightedness – eyeball shorter than normal – prescription lenses
Myopia – nearsightedness – eyeball elongated-prescription lenses
Amblyopia – dimness of vision in one eye, lazy eye. Tx: covering good eye to strengthen weak eye. If not tx by 8 or 9 yo blindness may occur
Astigmatism – irregular curvature of cornea or lens resulting in blurred vision or eye strain – prescription lenses

26. Vision Disorders (cont’d)
Strabismus – cross eyes – extrinsic muscles of eye don’t coordinate activity. Can be corrected by eye exercises or surgery.

27. Color blindness Cone cells of retina Genetic
More prevalent in males than females
Red-green – inability to distinguish between the two colors most common

28. Vision Simulations

29. Vision Disorders
Night blindness – difficult to see at night due to defect in rod cells
Color blindness – inability to distinguish colors – usually heredity

30. Vision Testing
Snellen Chart

31. Kindergarten eye chart

32. Vision Testing
Illiterate Eye Chart

33. Vision Testing
Near Vision Chart

34. Vision Testing
Ophthalmascope

35. Eye Injuries Chemical or solutions – rinse eye with eye wash or water
Fragments or particles – do not attempt to remove or rub eye, report to supervisor and seek medical attention

36. Application: Define the following disorders and S&S and Tx: Cataract
Conjunctivitis
Glaucoma
Macular degeneration
Detached retina

37. Eye Disorders
Cataract: Lens becomes cloudy Usually as a result of aging Sometimes by trauma Leading cause of blindness in world Sx: blurred vision, gradual vision loss, yellowing of colors, halos around lights Tx: lens implant

38. Cataract Surgery
cataract surgery video

39. Conjunctivitis Pink eye Highly contagious
Viral or bacterial or allergic
Redness, pain, itching, discharge
Tx.: antibiotics

41. Glaucoma Increased intraocular pressure Excess aqueous humor
Common after 40
2nd leading cause of blindness
Sx – loss of peripheral vision, halos around lights, limited night vision
Tx. – medication, surgery

42. Macular Degeneration Major cause of blindness Effects 10% of elderly
Disease of macula – part of retina
Caused by damage to blood vessels which nourish retina
S&S: blurred, distorted vision
Tx: currently no cure

43. Detached Retina Result of aging or traumatic injury Tear in the retina
Loss of peripheral vision followed by loss of central vision
Tx: early detection important. Laser surgery

44. Stye Hordeolum Tiny abscess at base of eyelash
Caused by inflammation of a sebaceous gland of eyelid
S&S: red, painful, swollen
Tx: warm, wet compresses

46. Diabetic Retinopathy Damage to retina due to long term diabetes
Swelling and leaking of vessels that supply blood to retina
S&S: pt sees red spots
Tx: Early detection – laser surgery

47. Vitreous Floaters Small, irregular shaped specks in vision field
Caused by tiny chunks of gel-like vitreous humor breaking off and floating in aqueous humor
Distracting, not a cause for alarm
Sudden, multiple floaters with flashes of light can be sign of retinal detachment

49. Pathway of light through the eye
The images in the light “hit” the cornea -> pupil ->lens
The light rays are bent or refracted ->retina ->rods and cones pick up the stimulus -> optic nerve -> optic chiasm (where the two optic nerves cross) -> optic tracts -> occipital lobe of the brain for interpretation
(Cornea – pupil-lens-retina-optic nerve-occipital lobe)

50. The Ear
Special sense organ designed to pick up sound waves and send the impulses to the auditory center of the brain

51. 3 anatomical regions of ear:
External ear – outer - hearing
Middle ear – tympanic membrane (eardrum) - hearing
Internal ear – inner – hearing and balance

52. The Outer Ear
Pinna- collects sound waves and directs them into the auditory canal to the eardrum or tympanic membrane, which separates the outer and middle ear
The auditory canal is lined with sebaceous or ceruminous glands that secrete a waxlike substance called cerumen – cleans, protects the ear, and lubricates

53. Outer Ear Pinna or auricle – cartilage
Collects sound waves and directs them to the auditory canal
external auditory meatus or auditory canal

54. Pinna- collects sound waves and directs them into the auditory canal
From auditory canal to the tympanic membrane (eardrum), which separates the outer and middle ear
The auditory canal is lined with sebaceous glands that secrete a waxlike substance called cerumen – protects the ear (ear wax)

55. Sound waves enter auricle -> external auditory canal -> vibrate on tympanic membrane

56. The Middle Ear The middle ear- cavity in the temporal bone
It connects with the pharynx (throat) by means of a tube called the Eustachian tube
The tube equalizes the ear pressure in the middle ear on both sides of tympanic membrane
A chain of 3 tiny bones called Ossicles is found in the middle ear
Malleus (Hammer)
Incus (Anvil)
Stapes (Stirrup)

57. Malleus, Incus, Stapes – transmit and amplify sound waves

59. What happens when we yawn:
A way to help bring pressure in the pharynx, Eustachian tube, and middle ear to same level as pressure outside the ear
Involuntary – yawn before we’re born
How Stuff Works: Yawning
Psychological? Physiological?

60. Inner Ear Most complex portion of ear
Separated from middle ear by membrane called oval window
Vestibule – first section – acts as entrance to 2 other parts of inner ear.
Cochlea – snail shell shaped – contains, delicate, hairlike cells, which make up Organ of Corti

61. Organ of Corti – receptor of sound waves – transmits impulses from sound waves to the auditory nerve temporal lobe interpreted as hearing
Semicircular canals – located in inner ear – contain liquid and delicate, hairlike cells that bend when liquid moves with head and body movements, maintains our sense of balance and equilibrium

63. Pathway of Hearing
Sound waves -> pinna (auricle) -> auditory canal -> tympanic membrane -> ossicles -> stimulate the receptors on the cochlea -> cochlear nerve (part of vestibulocochlear nerve) -> temporal lobe of the brain for interpretation

64. Ear disorders Otitis media – middle ear Infants/children
Eustachian tube not developed
Bacteria or virus
Pain, pus, swelling, fever

65. External Otitis Swimmer’s ear Bacterial or fungal
Caused by immersion in contaminated water
S&S: pain, fever, temporary hearing loss
Prevention: throughly cleaning and drying ear canal with alcohol based solution after swimming

66. Ear disorders Ostosclerosis
a chronic, progressive disease in which the stirrup becomes spongy and then hardens
results in hearing loss

67. Ear disorders Meniere’s disease
Affects the semicircular canals of the inner ear
Causes vertigo (dizziness)
May cause N/V and tinnitus (ringing or buzzing in the ear)
Treatments include medications for s/s

68. Tinnitus Ringing in ear
Hair cells in Organ of Corti that stimulate the auditory nerve are damaged
Normally, movement of hair cells triggered by sound waves
If damaged, hair cells move randomly, generating ringing in the ear
Most common cause: exposure to loud noise (including music)
Common and growing disorder: 50 million

69. Inner Ear Infection Labyrinthitis – infection of inner ear
Inflammation & swelling of inner ear
Semicircular canals
Vertigo (dizziness) and N&V

70. Ear disorders Presbycusis- deafness due to aging
Hearing loss can result from exposure to loud noise, conductive loss, and sensorineural damage
Hearing aids

71. Application:
Differentiate between swimmer’s ear, middle ear infection, inner ear infection.

72. Swimmer’s ear – external otitis media – bacterial or fungal – pain, fever, temp hearing loss
Otitis Media –middle ear infection – bacterial or viral – pain, swelling, pus – common in children bc Eustachian tube not fully developed

75. Application:
Using your smartphone, work with your table partner to research the following:
Research products OR services available for deafness or otitis media.
What products and/or services are available?
Discuss findings with your table partner
Be prepared to share your findings with class

76. What is a cochlear implant?

77. Tongue (Taste)
A mass muscle of tissue which has structures called papillae
There are taste buds for sweet, sour, salty, and bitter that are stimulated by the flavors of foods

78. Tongue/Taste facts
Facial, glossopharyngeal, and vagus nerves transmit taste sensations to brain
Flavor is a combination of taste, smell, texture or consistency, and temperature
75%-90% of what we taste is actually due to what we smell
Parietal lobe – taste/smell sensations

79. Lab: What is difference bw taste and flavor?
Hold your nose, chew jelly bean. What flavor is jelly bean? Describe what you taste. Let go of your nose. Continue chewing jelly bean. What happens? Did you get a sudden rush of flavor? Can you better identify flavor of jelly bean? What did you learn from this simple experiment?

80. Tongue disorders Hairiness- over growth of the normal projections
Discoloration- tongue may appear black if the person takes bismuth preparations for an upset stomach
Infection- may be the result of tongue piercings
Cancer- sores, lumps, discoloration, etc

81. Hairy tongue, smoker’s tongue, cancer of tongue

82. The Nose (Smell) Detects about 10,000 smells
The specialized patch of tissue called the olfactory epithelium has the receptors that send stimuli to the olfactory nerve
Smell accounts for about 90% of what we think of taste

83. Rhinitis Inflammation of mucous membranes that line nasal passages
Most common cause – common cold
Allergies, chemical odors, illegal drugs

84. Why do I get a runny nose?
Inflammation of nasal membranes causes release of histamines
Histamines – molecules which trigger a reaction that produces congestion and drainage
Tx: removing or minimizing irritant, antihistamines (decrease production of histamines)

85. Nose disorders Rhinitis- inflammation of the lining of the nose
Nasal polyps- growths in the naval cavity
Deviated nasal septum- a bend in the cartilage structure of the septum

86. Touch
The sense of touch is due to very sensitive neurons that respond to pressure, heat, cold, touch, and pain
Each receptor perceives only one type of sense

87. Careers related to Special Senses
Define:
Audiologist
Ophthalmologist
Optometrist
Otolaryngologist