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Senses. Hearing. Structures of the EAR . Outer Ear Pinna External auditory canal Tympanic membrane (ear drum) Middle Ear Malleus (hammer) Incus (anvil) Stapes (stirrup) Inner Ear Cochlea Semicircular canals (labyrinth). Ear and Hearing.

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Presentation Transcript
Senses

Senses

Hearing


Structures of the ear
Structures of the EAR

  • Outer Ear

    • Pinna

    • External auditory canal

    • Tympanic membrane (ear drum)

  • Middle Ear

    • Malleus (hammer)

    • Incus (anvil)

    • Stapes (stirrup)

  • Inner Ear

    • Cochlea

    • Semicircular canals (labyrinth)


Ear and hearing
Ear and Hearing

  • Outer ear – funnels sound waves into the outer ear canal, to the eardrum, which cause it to vibrate

  • Middle ear – vibrations are conducted through 3 “air filled” ossicles – amplify and transmit mechanical movements to oval window (cochlea)

  • Inner ear – vibrations of the oval window produce pressure waves in the “fluid” within the cochlea. Cochlea transduces energy of vibrating fluid into action potentials


Cochlea
Cochlea

  • Cochlea is filled with fluid

  • The middle ear passes sound vibrations along to the cochlea

  • The waves in the fluid cause hair cells (mechanoreceptors to vibrate)

  • The vibration of these cells causes a action potential to be sent to the brain via the auditory nerve.


Detection of sound
Detection of Sound

  • Sound is detected by the frequency of impulses in the sensory neuron. Quality of sound is determined by:

    • Volume (loudness) of a sound depends on amplitude of sound waves produced.

    • Pitch (shrillness) is determined by number of vibrations per second. Humans can hear pitch in range of 20 to 20,000 Hz. Dogs 40,000 Hz.


Equilibrium semicircular canals
Equilibrium - Semicircular Canals

  • Detect orientation (body position) and gravity

  • Hair cells along 3 planes respond to shifts of liquid within the cochlea.

  • The signals from this

    part of this organ are

    sent to the cerebellum


Deafness
Deafness

  • 1 in every 1,000 newborns is profoundly deaf, while 1 in 20 has significant hearing impairment.

  • Most of the 28 million deaf or hearing-impaired people in the United States were born with normal hearing.

  • Deafness usually results from overexposure to loud noise, disease or old age. Genetics is also a cause of hearing loss, especially children.


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