Transcript Chapt14 Lecture 13ed Pt 3

Human Biology
Sylvia S. Mader
Michael Windelspecht
Chapter 14
Senses
Lecture Outline
Part 3
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14.5 Sense of Hearing
1. Divisions of the ear: Outer ear
•
Includes
– ______: the external ear flap that catches
sound waves
– ____________: directs sound waves to the
tympanic membrane
• Lined with fine hairs and modified sweat
glands that secrete ear wax
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14.5 Sense of Hearing
2. Divisions of the ear: Middle ear
•
Includes
– _______________ (eardrum): membrane
that vibrates to carry sound waves to the
bones
– __________ (malleus, incus, stapes): 3
small bones that amplify sound waves
– __________ (Eustachian tube): a tube that
connects from the throat to the middle ear
and is used to equalize pressure so the
eardrum does not burst
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14.5 Sense of Hearing
Following the sound wave
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Outer ear
Middle ear
Inner ear
stapes
semicircular canals
incus
malleus
oval window
vestibule
vestibular
nerve
pinna
cochlear
nerve
cochlea
tympanic
membrane
auditory
canal
temporal
bone
round window
auditory
tube
Figure 14.12 The three divisions of the human ear.
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14.5 Sense of Hearing
3. Divisions of the ear: Inner ear
•
Important for both hearing and balance
•
3 areas: cochlea, semicircular canals, vestibule
•
_______ (middle ear bone) – vibrates and
strikes the membrane of the oval window
causing fluid waves in the cochlea
•
_______ – functions in gravitational equilibrium
•
_________ – functions in rotational equilibrium
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14.5 Sense of Hearing
The inner ear: The cochlea
•
The cochlea converts vibrations into nerve
impulses.
•
It contains the spiral organ (organ of Corti) which
is the sense organ containing hairs for hearing.
– Bending of embedded hairs causes vibrations
that initiate nerve impulses which travel to the
cochlear nerve and then to the brain.
– Pitch is determined by varying wave
frequencies that are detected by different parts
of the spiral organ.
– Volume is determined by the amplitude of
sound waves.
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14.5 Sense of Hearing
The inner ear: Hearing
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semicircular
canals
oval
window
cochlea
stapes
round window
vestibular
canal
cochlear
canal
tympanic
canal
cochlear
nerve
Cochlea cross section
tectorial membrane
stereocilia
basilar
membrane
hair cell
cochlear nerve
tympanic
canal
Spiral organ
Figure 14.13 How the spiral organ
(organ of Corti) translates sound waves
into nerve signals.
Stereocilia
(stereocilia): © P. Motta/SPL/ Photo Researchers, Inc.
2 µm
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14.5 Sense of Hearing
The inner ear: The spiral organ
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
tectorial membrane
stereocilia
basilar
membrane
hair cell
cochlear nerve
tympanic
canal
Spiral organ
Figure 14.13 How the spiral organ (organ of Corti) translates sound waves into nerve signals.
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14.6 Sense of Equilibrium
The inner ear: Semicircular
canals and vestibule
•
Detects angular movement (_____________
____________)
– Depends on hair cells at the base of each
semicircular canal (ampulla)
•
Detects movement of the head in the vertical
and horizontal planes (gravitational
equilibrium)
– Depends on hair cells in the utricle and saccule
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14.6 Sense of Equilibrium
The inner ear: Balance
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
semicircular
canals
receptor in ampulla
endolymph
Vestibular nerve
ampullae
cochlea
utricle
saccule
endolymph
cupula
otoliths
stereocilia
otolithic
membrane
Hair cell
hair cell
Supporting cell
supporting
cell
vestibular
nerve
Vestibular nerve
flow of endolymph
Flow of otolithic
membrane
Figure 14.14 The
mechanoreceptors
of the inner ear and
the sense of
balance.
a. Rotational equilibrium: receptors in ampullae of semicircular canal
kinocilium
stereocilia
b. Gravitational equilibrium: receptors in utricle and saccule of vestibule
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14.6 Sense of Equilibrium
Noise pollution
•
Loud noises (>85 decibels) or chronic noise
can damage inner ear cells.
•
Environmental noise can cause mental health
issues such as inability to concentrate, an
increase in irritability, and anxiety.
•
Noise can cause loss of sleep and productivity,
and can lead to anxiety.
•
What should be done about noise pollution?
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