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Special senses blog
Special senses blog
Special senses blog
Special senses blog
Special senses blog
Special senses blog
Special senses blog
Special senses blog
Special senses blog
Special senses blog
Special senses blog
Special senses blog
Special senses blog
Special senses blog
Special senses blog
Special senses blog
Special senses blog
Special senses blog
Special senses blog
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Special senses blog

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Transcript

  • 1. The Special Senses
  • 2. Vision
    • Our dominant sense
    • Estimated 70% of all sensory receptors are in the eyes
    • Believed over 50% of cerebral cortex is used for visual processing
    • The eye has a diameter around one inch
    • Eyebrows …. Function?
    • Keep sweat from dripping in your eyes
    • Eyelids & eyelashes - protection
  • 3. Accessory Eye Structures:
    • Tarsal glands:
    • Lubricates eyelids/prevents from sticking to eye
    • Conjunctiva:
    • Transparent mucous membrane; prevents eye from drying out
    • Caruncle - produces “Sand Man’s Eye Sand”
    • Lacrimal apparatus:
    • Lacrimal gland, lacrimal canal, lacrimal sac, nasolacrimal duct
    • Lysosyme - destroys bacteria
    • Tears - why do we cry??
  • 4. The Fibrous Tunic
    • Dense avascular connective tissue
    • Sclera: White portion of eye. Dense irregular c.t.
    • Cornea: Clear portion of eye. Dense regular c.t.
    • Very tough material
    • Needs a blood supply….but from where??
  • 5. The Vascular Tunic
    • Choroid: Includes blood vessels. Nourishment
    • Ciliary bodies - holds suspensory ligaments
    • Suspensory ligaments - holds lens
    • Iris - colored part of eye; smooth muscle forms pupil
  • 6. The Sensory Tunic
    • The retina:
    • Image we see projected onto it
    • Image is upside down, brain must flip it
    • Optic disc is blind spot
    • Optic nerve attaches here
  • 7. The Lens
    • Biconvex
    • Avascular…why??
    • Contains crystalline proteins (crystallins)
    • Convert sugar to energy for use by the lens
    • New fibers added continually through life
    • Lens gets bigger and harder to see out of
    • Cataracts - most occur from age
    • Also from diabetes, smoking, UVB radiation
  • 8. The Humors
    • Vitreous humor: fills most of the space inside the eye
    • Posterior to lens
    • Made of collagen and ground substance
    • Transmits light, supports lens and retina, contributes to good eye pressure
    • Formed in embryo, lasts a lifetime
    • Aqueous humor: fills space anterior to lens
    • Continually drains (and produced back at the same rate)
    • Glaucoma can result if drainage is blocked
    • Too much pressure damages optic nerve
  • 9. Rods & Cones
    • Rods: Dim light and peripheral vision receptors
    • Cones: Operate in bright light
    • Cones provide high-acuity color vision
  • 10. Homeostatic Imbalances
    • Myopia:
    • Also called “nearsightedness”
    • Can see close objects without a problem
    • Occurs from an eyeball that’s too long
    • Hyperopia:
    • Also called “farsightedness”
    • Can see objects farther away
    • Occurs from an eyeball that’s too short
  • 11. Taste & Smell
    • Why do we taste?
    • To test/judge our environment
    • Taste & smell are linked together
    • Taste vs flavor…?
    • Taste is limited to four basic sensations
    • Flavor is what we associate with taste
    • “ This tastes good!!” … statement is flawed!
    • Tasting food = 80% smell.
    • Smell/taste is genetically hardwired into us!
  • 12. Taste Buds
    • Called “papillae”
    • Two major types:
    • Fungiform papillae- small, mushroom-shaped
    • Scattered over entire tongue surface
    • Most abundant on tip and sides
    • Taste receptors ON TOP OF these papillae
    • Circumvallate papillae - largest, least numerous
    • Form inverted “V” at back of tongue
    • Taste receptors ON THE SIDES OF these papilla
  • 13. Taste Sensations
    • Sweet - detect carbohydrates; mother’s milk is sweet
    • Salty - satisfies body’s need for minerals, helps nervous & muscular system
    • Sour - possibly for vitamin detection
    • Bitter - poison detector!
  • 14. Taste Bud Anatomy
    • Each consists of 40-100 epithelial cells of three major types:
    • Supporting cells - form majority of taste bud
    • Receptor (gustatory) cells - insulated by supporting cells
    • Basal cells - act as stem cells
    • Taste bud cells shed every 10-14 days!
    • Taste buds also include gustatory hairs extending through taste pores
  • 15. Structures of the Ear
    • Outer Ear:
    • Includes auricle (pinna), lobule, external auditory canal, and tympanum
    • Canal lined with cerumen
    • Tympanum responsible for transmitting vibrations
  • 16.
    • Middle Ear:
    • Includes malleus, incus, stapes
    • Small bones which transmit vibrations to inner ear
    • Also called hammer, anvil, stirrup
  • 17.
    • Inner Ear:
    • Cochlea - includes spiral organ of Corti, and sensory hairs
    • Semicircular canals - help with balance!
  • 18. Homeostatic Imbalances of the Ear
    • Conduction deafness:
    • Ear canal is blocked
    • Sensorineural deafness:
    • Permanent hearing loss/damage
    • Tinnitus:
    • Constant ringing in your ears
  • 19. Frequencies and Loudness
    • Range of hearing is between 20-20,000 Hz
    • Most sensitive between 1500-4000 Hz
    • Loudness measured in decibels (dB)
    • Logarithmic in nature
    • Normal conversation = 50 dB
    • Noisy restaurant = 70 dB
    • Danger zone = 90 dB and above
    • Rock concert = 120 dB
    • Pain threshold = 130 dB

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