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section 2, chapter 12
Smell, Taste, and Hearing

• Sensory receptors are within large, complex sensory
organs in the head
...
Sense of Smell
• Olfactory receptors
• Bipolar Chemoreceptors
• Respond to chemicals (called odorants) dissolved in liquid...
Olfactory Receptors

Figure 12.5 Olfactory receptors. (a) columnar epithelial cells support olfactory
receptor cells, whic...
Olfactory Nerve Pathways
• Once olfactory receptors are stimulated, nerve impulses travel through
•
•Olfactory nerves
olfa...
Olfactory Stimulation
• Olfactory organs located high in the nasal cavity above the
usual pathway of inhaled air
• Olfacto...
Sense of Taste
• Taste buds
• Organs of taste
• Located on papillae of tongue, roof of mouth, linings of
cheeks and walls ...
Taste Receptors
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Papillae

Ta...
Taste Sensations
• Four primary taste sensations
• Sweet – stimulated by carbohydrates
• Sour – stimulated by acids
• Salt...
Taste Nerve Pathways
• Sensory impulses from taste receptors travel along:
• Cranial nerves to…
• Medulla oblongata to…
• ...
Sense of Hearing
• Ear
• Organ of hearing
• Three (3) sections:
• External ear
• Middle ear
• Inner ear

10
External Ear
• Auricle
• Collects sounds waves
• External auditory meatus
• Lined with ceruminous
glands
• Carries sound t...
Middle Ear
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

• Tympanic cavity...
Auditory Tube
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

• Also known a...
Inner Ear
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

• Complex system o...
Inner Ear
• Three (3) parts of labyrinths:
• Cochlea
• Functions in hearing
• Semicircular canals
• Functions in
equilibri...
Cochlea
• Scala vestibuli
• Upper compartment
• Leads from oval
window to apex of
spiral
• Part of bony labyrinth
• Scala ...
Cochlea
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

• Cochlear duct
• Po...
Organ of Corti
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

• Group of he...
Organ of Corti
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Cochlear duct...
Auditory Nerve Pathways
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Audi...
Summary of the Generation of
Sensory Impulses from the Ear

21
Sense of Equilibrium
• Static equilibrium
• Vestibule
• Senses position of
head when body is not
moving

• Dynamic Equilib...
Vestibule
• Utricle
• Communicates with
saccule and membranous
portion of semicircular
canals
• Saccule
• Communicates wit...
Macula
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

• Responds to changes...
Semicircular Canals
• Three (3) canals at right angles
• Ampulla
• Swelling of membranous
labyrinth that communicates
with...
Crista Ampullaris
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Copyright ...
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Transcript of "section 2, chapter 12: smell, taste, hearing"

  1. 1. section 2, chapter 12 Smell, Taste, and Hearing • 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 1
  2. 2. Sense of Smell • Olfactory receptors • Bipolar Chemoreceptors • Respond to chemicals (called odorants) dissolved in liquids • Olfactory organs • Olfactory epithelium - contain olfactory receptors and supporting epithelial cells • Cover parts of nasal cavity, superior nasal conchae, and a portion of the nasal septum 2
  3. 3. Olfactory Receptors Figure 12.5 Olfactory receptors. (a) columnar epithelial cells support olfactory receptor cells, which have cilia at their distal ends. The olfactory receptors pass through olfactory foramina in the cribriform plate and synapse with the olfactory bulb in the brain. (b) Olfactory epithelium cover the upper nasal cavity and superior nasal conchae.
  4. 4. Olfactory Nerve Pathways • Once olfactory receptors are stimulated, nerve impulses travel through • •Olfactory nerves olfactory bulbs olfactory tracts limbic system (for emotions) & olfactory cortex (for interpretation) The limbic system, which is involved with emotions and memory is strongly effected by smell. 4
  5. 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 5
  6. 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 6
  7. 7. Taste Receptors Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Papillae Taste buds Epithelium of tongue (a) Taste cell Taste hair Supporting cell Taste pore Connective tissue Sensory nerve fibers 7 (b)
  8. 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 8
  9. 9. Taste Nerve Pathways • Sensory impulses from taste receptors travel along: • Cranial nerves to… • Medulla oblongata to… • Thalamus to… • Gustatory cortex (for interpretation) 9
  10. 10. Sense of Hearing • Ear • Organ of hearing • Three (3) sections: • External ear • Middle ear • Inner ear 10
  11. 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 Auricle Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Semicircular canals Incus Stapes Malleus Cochlea Vestibulocochlear nerve Oval window (under stapes) Round window Tympanic cavity Tympanic membrane External acoustic meatus Auditory tube Pharynx 11
  12. 12. Middle Ear Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. • Tympanic cavity • Air-filled space in temporal bone • Auditory ossicles • Vibrate in response to tympanic membrane • Malleus, incus and stapes • Hammer, anvil and stirrup • Oval window • Opening in wall of tympanic cavity • Stapes vibrates against it to move fluids in inner ear Auricle Semicircular canals Incus Stapes Malleus Cochlea Vestibulocochlear nerve Oval window (under stapes) Round window Tympanic cavity Tympanic membrane External acoustic meatus Auditory tube Pharynx 12
  13. 13. Auditory Tube Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. • Also known as the Eustachian tube • Connects middle ear to throat • Helps maintain equal pressure on both sides of tympanic membrane • Usually closed by valvelike flaps in throat Auricle Semicircular canals Incus Stapes Malleus Cochlea Vestibulocochlear nerve Oval window (under stapes) Round window Tympanic cavity Tympanic membrane External acoustic meatus Auditory tube Pharynx 13
  14. 14. Inner Ear Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. • Complex system of labyrinths • Osseous labyrinth • Bony canal in temporal bone • Filled with perilymph • Membranous labyrinth • Tube within osseous labyrinth • Filled with endolymph Bony labyrinth Perilymph Membranous labyrinth Endolymph Bony labyrinth (contains perilymph) Membranous labyrinth (contains endolymph) Semicircular canals Utricle Saccule Vestibular nerve Cochlear nerve Scala vestibuli (cut) Scala tympani (cut) Cochlear duct (cut) containing endolymph Ampullae Oval Vestibule Round Maculae window window (a) Cochlea 14
  15. 15. Inner Ear • Three (3) parts of labyrinths: • Cochlea • Functions in hearing • Semicircular canals • Functions in equilibrium • Vestibule • Functions in equilibrium Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Bony labyrinth Perilymph Membranous labyrinth Endolymph Bony labyrinth (contains perilymph) Membranous labyrinth (contains endolymph) Semicircular canals Utricle Saccule Vestibular nerve Cochlear nerve Scala vestibuli (cut) Scala tympani (cut) Cochlear duct (cut) containing endolymph Ampullae Oval Vestibule Round Maculae window window (a) Cochlea 15
  16. 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 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Stapes vibrating in oval window Helicotrema Scala vestibuli filled with perilymph Vestibular membrane Basilar membrane Scala tympani filled with perilymph Round window Membranous labyrinth Cochlear duct filled with endolymph 16
  17. 17. Cochlea Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. • Cochlear duct • Portion of membranous labyrinth in cochlea • Vestibular membrane • Separates cochlear duct from scala vestibuli • Basilar membrane • Separates cochlear duct from scala tympani Scala vestibuli (contains perilymph) Vestibular membrane Branch of cochlear nerve Cochlear duct (contains endolymph) Spiral organ (organ of Corti) Basilar membrane Scala tympani (contains perilymph) (a) 17
  18. 18. Organ of Corti Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. • 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 • Nerve impulse generated Scala vestibuli (contains perilymph) Vestibular membrane Cochlear duct (contains endolymph) Spiral organ (organ of Corti) Branch of cochlear nerve Basilar membrane Scala tympani (contains perilymph) (a) Tectorial membrane Hair cells (b) Branch of cochlear nerve Nerve fibers Supporting cells Basilar membrane 18
  19. 19. Organ of Corti Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Cochlear duct Tectorial membrane Scala tympani Hair cells Basilar membrane (a) (b) a: © John D. Cunningham/Visuals Unlimited; b: © Fred Hossler/Visuals Unlimited 19
  20. 20. Auditory Nerve Pathways Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Auditory cortex (temporal lobe) Thalamus Medial geniculate body of thalamus Midbrain Pons Cochlear nuclei Superior olivary nucleus Medulla oblongata Vestibulocochlear nerve 20
  21. 21. Summary of the Generation of Sensory Impulses from the Ear 21
  22. 22. Sense of Equilibrium • Static equilibrium • Vestibule • Senses position of head when body is not moving • Dynamic Equilibrium • Semicircular canals • Senses rotation and movement of head and body 22
  23. 23. Vestibule • Utricle • Communicates with saccule and membranous portion of semicircular canals • Saccule • Communicates with cochlear duct • Macula • Hair cells of utricle and saccule Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Ampullae of semicircular canals Vestibulocochlear nerve Cochlea Utricle Cochlear duct Maculae Saccule Vestibule 23
  24. 24. Macula Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. • Responds to changes in head position • Bending of hairs results in generation of nerve impulse Hairs of hair cells bend Gelatinous material sags Otoliths Macula of utricle Hair cells Sensory nerve fiber Gravitational force Supporting cells (a) Head upright (b) Head bent forward 24
  25. 25. Semicircular Canals • Three (3) 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 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Ampullae of semicircular canals Vestibulocochlear nerve Utricle Cochlea Cochlear duct Maculae Saccule Vestibule 25
  26. 26. Crista Ampullaris Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Endolymph Semicircular canal Cupula Crista ampullaris (a) Head in still position Ampulla Crista ampullaris Hairs Hair cell Supporting cells Sensory nerve fibers (b) Head rotating (c) End of section 2, chapter 12 26
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