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Special Senses

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Special Senses sensory receptors are within large, complex sensory organs in the head smell in olfactory organs taste in taste buds hearing and equilibrium in ears – PowerPoint PPT presentation

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Title: Special Senses


1
Special Senses
  • sensory receptors are within large, complex
    sensory organs in the head
  • smell in olfactory organs
  • taste in taste buds
  • hearing and equilibrium in ears
  • sight in eyes

connected
2
Sense of Smell
  • Olfactory Receptors
  • chemoreceptors
  • respond to chemicals dissolved in liquids
  • Olfactory Organs
  • contain olfactory receptors and supporting
    epithelial cells
  • cover parts of nasal cavity, superior nasal
    conchae, and a portion of the nasal septum

3
Olfactory Receptors
4
Olfactory Nerve Pathways
  • Once olfactory receptors are stimulated, nerve
    impulses travel through
  • olfactory nerves olfactory bulbs
    olfactory tracts limbic system (for
    emotions-moms apple pie.) and olfactory cortex
    (for interpretation)

5
Olfactory Stimulation
  • olfactory organs located high in the nasal
    cavity above the usual pathway of inhaled air
  • olfactory receptors undergo sensory adaptation
    rapidly
  • sense of smell drops by 50 within a second
    after stimulation
  • Olfactory Code
  • hypothesis
  • odor that is stimulated by a distinct set of
    receptor cells and its associated receptor
    proteins (the variety stimulated determines the
    smell)

6
Sense of Taste
  • Taste Buds
  • organs of taste
  • located on papillae of tongue, roof of mouth,
    linings of cheeks and walls of pharynx
  • Taste Receptors
  • chemoreceptors
  • taste cells modified epithelial cells that
    function as receptors
  • taste hairs microvilli that protrude from taste
    cells sensitive parts of taste cells

7
Taste Receptors
8
Taste Sensations
  • Four Primary Taste Sensations
  • sweet stimulated by carbohydrates
  • sour stimulated by acids
  • salty stimulated by salts
  • bitter stimulated by many organic compounds

Spicy foods activate pain receptors (and sour)
9
Taste Nerve Pathways
  • Sensory impulses from taste receptors travel
    along
  • cranial nerves to
  • medulla oblongata to
  • thalamus to
  • gustatory cortex (for interpretation)

10
Hearing
Ear organ of hearing
  • Three Sections
  • External
  • Middle
  • Inner

11
External Ear
  • auricle
  • collects sounds waves
  • external auditory meatus
  • lined with ceruminous glands
  • carries sound to tympanic membrane
  • terminates with tympanic membrane
  • tympanic membrane
  • vibrates in response to sound waves

12
Middle Ear
  • tympanic cavity
  • air-filled space in temporal bone
  • auditory ossicles
  • vibrate in response to tympanic membrane
  • malleus, incus, and stapes
  • oval window
  • opening in wall of tympanic cavity
  • stapes vibrates against it to move fluids in
    inner ear

13
Auditory Tube
  • eustachian tube
  • connects middle ear to throat
  • helps maintain equal pressure on both sides of
    tympanic membrane (think altitude-pop)
  • usually closed by valve-like flaps in throat

14
Inner Ear
  • complex system of labyrinths
  • osseous labyrinth
  • bony canal in temporal bone
  • filled with perilymph
  • membranous labyrinth
  • tube within osseous labyrinth
  • filled with endolymph

15
Inner Ear
  • Three Parts of Labyrinths
  • cochlea
  • functions in hearing
  • semicircular canals
  • functions in equilibrium
  • vestibule
  • functions in equilibrium

16
Cochlea
  • Scala vestibuli
  • upper compartment
  • leads from oval window to apex of spiral
  • part of bony labyrinth
  • Scala tympani
  • lower compartment
  • extends from apex of the cochlea to round window
  • part of bony labyrinth

17
Cochlea
  • Cochlear duct
  • portion of membranous labyrinth in cochlea
  • Vestibular membrane
  • separates cochlear duct from scala vestibuli
  • Basilar membrane
  • separates cochlear duct from scala tympani

18
Organ of Corti
  • group of hearing receptor cells (hair cells)
  • on upper surface of basilar membrane
  • different frequencies of vibration move
    different parts of basilar membrane
  • particular sound frequencies cause hairs of
    receptor cells to bend
  • Ca influx causes NT release onto sensory nerve
  • AP generated-to medulla-to thalamus-to auditory
    cortex (temporal)
  • Some crossover occurs

19
Organ of Corti
20
Auditory Nerve Pathways
21
Summary of the Generation of Sensory Impulses
from the Ear
22
Equilibrium
  • Dynamic Equilibrium
  • semicircular canals
  • sense rotation and movement of head and body
  • Static Equilibrium
  • vestibule
  • sense position of head when body is not moving

23
Vestibule
  • Utricle
  • communicates with saccule and membranous portion
    of semicircular canals
  • Saccule
  • communicates with cochlear duct
  • Mucula
  • hair cells of utricle and saccule

24
Macula
  • responds to changes in head position
  • bending of hairs results in generation of nerve
    impulse

25
Semicircular Canals
  • three canals at right angles
  • ampulla
  • swelling of membranous labyrinth that
    communicates with the vestibule
  • crista ampullaris
  • sensory organ of ampulla
  • hair cells and supporting cells
  • rapid turns of head or body stimulate hair cells

26
Crista Ampullaris
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