5. Quiz
• Chewing gum, yawning, and swallowing in elevators and airplanes
help to move air through the ______ tubes, which equalizes air
pressure upon ascent and descent.
A. optic
B. tympanic
C. cochlear
D. auditory (eustachian)
7. Structure of the cochlea
• Greek kokhlos “land
snail”
• Located in the inner ear.
• Three ducts filled with
lymph
• Form a labyrinth内耳迷路
8. The three longitudinal parallel canals
• Vestibular canal前庭管
• Uppermost - connected to the oval
window and the tympanic canal
• Contains perilymph
• Cochlea duct蜗管
• Middle
• Contains endolymph
• Contains organ of Corti
• Tympanic canal鼓管
• Lowermost - connected the round
window and the vestibular canal
• Contains perilymph
9. The windows
• Oval window卵圆窗 fenestra
vestibule
• Vibrations that contact the
tympanic membrane
travel through the three
ossicles and into the inner
ear through the Vestibular
canal.
• Round window圆窗
• Allow movement of the
fluid within the cochlea as
the stepes moves into the
oval window.
10. Quiz
• The canals contained in the spiral-shaped tubular cochlea include
_____________.
A. the vestibular, cochlear, and tympanic canals
B. the utricle and saccule
C. all branches of the organ of Corti
D. the eustachian canal and the eerie canal
11. organ of Corti
柯蒂氏器
organ of Corti =
• basilar membrane底膜+
• sensory hair cells感觉毛状细胞 +
• tectorial membrane盖膜
(Reissner’s membrane)
• basilar membrane
• separates the tympanic canal
from the cochlear duct
• supports a layer of sensory hair
cells
15. Transmission of sound
Sound
wave
Pinna外耳壳
Auditory
canal外耳道
ear drum
鼓膜 vibrates
Three cranial
bones听小骨
amplifies the
vibration
Oval window
卵圆窗
Endolymph
内淋巴液 vibrates
Tectorial
membrane盖膜
vibrates
Sensory hair cells
毛状细胞 vibrates
and generate
nerve impulses
Perilymph
外淋巴液 of the
vestibular canal
前庭管 vibrates
Vibration
transmitted to the
whole cochlea
Basilar membrane
地膜 vibrates
Auditory nerve听
神经
Cerebral cortex
大脑皮层
Hearing centre
听觉中枢
Outer ear Middle ear Inner ear
16. Quiz
• In the ear, when the cilia of the hair cells bend, nerve impulses
travel to the oval window.
A. True
B. False
17.
18.
19. Transmission of sound in the inner ear
No Step Type of info
1. Sound waves are transmitted into the auditory canal and causing the eardrum to vibrate. Sound wave
2. The three small cranial bones amplify the vibrations about 20 times, pass the vibrations to
the oval window which connects to inner ear.
Mechanical
vibration
3. The vibrations cause the perilymph in the vestibular canal to vibrate and transmitted rapidly
to whole cochlea
Wave
4. Vibration of perilymph causes the basilar membrane to vibrate. Wave
5. Vibration of basilar membrane causes the tectorial membrane that is flowing in the
endolymph in the to stimulate the sensory hair cells of organ Corti to flap or swing.
Wave
6. The swinging is then changed to nerve impulse which is sent to hearing center of cerebral
cortex through auditory nerve and produce hearing.
Nerve
impulse
20. Quiz
• Sound information is transmitted as vibrations (waves). Which of the following is
a correct order of structures used to transmit these vibrations to the Organ of
Corti? None of the lists are necessarily complete in terms of listing all structures
involved.
A. oval window to middle ear ossicles to round window to endolymph to
perilymph
B. oval window to middle ear ossicles to round window to perilymph to
endolymph
C. middle ear ossicles to tympanic membrane to endolymph to perilymph to
basilar membrane
D. tympanic membrane to middle ear ossicles to oval window to perilymph to
basilar membrane
E. tympanic membrane to middle ear ossicles to oval window to endolymph to
perilymph
21. How can we tell the difference in sounds?
• Sounds of different
frequencies stimulate hair
cells in different parts of
the organ of Corti,
allowing us to perceive
the subtleties of sounds
such as speech and music.
• We can also tell the origin
of the sound as sound will
not reach both ears at the
same time due to the
difference of distance
from the source to our
left and right ear.
• Some Owl species have
asymmetrically set ear
openings
22. Quiz
• Loud noises cause the fluid of the cochlea to vibrate ___________.
A. to a lesser degree
B. to a greater degree
C. there is no effect on degree of vibration
23. Quiz
• What is the punchline
(funny bit) of this
comic?
• Dogs, as many other
animals, have a
difference range of
frequency of sound
where they can hear.
24. Conclusion
• Hearing is initiated: Eardrum → ossicles → oval window → perilymph
→ cochlear duct → endolymph → basilar membrane → tectorial
membrane → hair cells.
• Nerve impulses generated by the hair cells are sent to hearing center
of cerebral cortex through auditory nerve.
• Sounds of different frequencies stimulate hair cells in different parts
of the organ of Corti.
• The origin of the sound is interpreted based on the time difference of
stimulation occurs in the left and right ear.
26. Sense of balance
• Sense of balance helps
prevent humans and animals
from falling over when
standing or moving.
• Balance is the result of a
number of body systems
working together:
• the eyes (visual system)
• ears (vestibular system =
semicircular canal半规管 +
vestibule前庭) and
• Proprioception receptors
27. Function of vestibule and semicircular canal
• detect the location of the
head
• maintain balance
• Vestibule
• tilting倾斜
• static equilibrium静态平衡
• Semilunar canal
• rotation旋转
• dynamic equilibrium转动平衡
• lack the auditory function
28. Quiz
• The sense of balance includes ___________ equilibrium.
A. horizontal and vertical
B. auditory
C. dynamic and static
D. amplitude and pitch
30. Structure of the semicircular canal
• It is composed by three semi-
circular tubules which are arranged
in three planets at right angles to
each other.
• The orientations of the canals cause
a different canal to be stimulated by
movement of the head in different
planes.
• Species that are agile and have fast
locomotion have larger canals
relative to their body size than those
that move slowly.
31. Within the canals
• The canals are filled with endolymph.
• At the base of each canal is a swelling called ampulla壶腹.
• On the ampulla are the sensory hair cells感觉毛细胞and enclosed by
gelatinous mass胶质物.
32. Quiz
• The base of each of the three semicircular canals in the ear is called
the ______.
A. eustachian
B. ampulla
C. spiral organ (organ of Corti)
D. otolith
33. Detection of rotation
• The sensory hair
cells are
stimulated and
produce nerve
impulse.
• Nerve impulses
are sent to the
brain through
the auditory
nerve.
• When the head rotate to a certain direction, endolymph in the tube will
move to opposite direction.
• This causes the direction of gelatinous mass changed.
34.
35. Response of detection
• The impulse sent to cerebellum
小脑 for the muscle to produce
corresponding reaction in order
to balance the body.
• The impulse sent to cerebrum大
脑 for regulating the direction of
movement.
36. Motion sickness
• When a rotation suddenly stops.
• Endolymph inside keep on moving due
to inertia.
• Nerve impulse continues to transmit.
• The ears, however, no longer detects
motion.
• The disagreement between visually
perceived movement and the vestibular
system's sense of movement cause the
dizziness feeling.
37. Quiz
• One form of motion sickness results because of continuous
movement of __________ in the ear.
A. fluid in the semicircular canals
B. otoliths in the utricle and saccule
C. gelatinous material in the ampullae
D. air in the eustachian tube
38. Structure of the vestibule前庭
• vestibular apparatus =
• utricle椭圆囊+ saccule球状囊
• The utricle, which lies
horizontally, and saccule,
which is oriented vertically.
• Both the utricle and saccule
contain endolymph, sensory
hair cells, gelatinous mass
and otoliths耳石.
39. hair cells long microvilli (hatched circles) on
the utricle
SEM image of the hair cells long microvilli
(hatched circles) on the utricle, revealing
long stereocilia (up to 5 µm in length)
partially surround a 9-µm kinocilium. (b)
TEM image through the elongate hair cells
and peripheral nerve bed. (c) The top of the
cell, buttressed by a long microvillus. cm,
cell membrane; cp, cuticular plate; hc, hair
cell; jc, junctional complex; lmv, long
microvilli; n, nucleus; ps, phagosomes; pnf,
peripheral nerve fibres; smv, short
microvilli.
40. Function of the vestibule
• The left and right utricular maculae are in the same, approximately
horizontal, plane.
• These can help to sense the situation of head by detecting linear
acceleration and the pull of gravity and maintain balance at rest.
41. Mechanism of detection
• The endolymph moves.
• The gravity pulls the gelatinous matrix and
the otoliths to one side.
• The hair cells are stimulated.
• Nerve impulses are sent to the brain(both
cerebellum and cerebrum) through the
auditory nerve.
42.
43. Quiz
• Movement of the otoliths within the utricle and the saccule is
important for static equilibrium in the ear.
A. True
B. False
44. Conclusion
• The sense of balance is the result of a number of body systems
working together: the eyes, the ears (vestibular system = semicircular
canal + vestibule) and the proprioception receptors.
• The vestibule detects tilting of the head while the semilunar canal
detects rotation of the head.
• The semilunar canal contains ampulla.
• The vestibule contains otoliths.
https://www.youtube.com/watch?v=toGCC6SrKw8
The human ear is divided into three parts. 1. the outer ear 2. the middle ear 3. the inner ear Air-conducted sound waves must move through these three parts in order for sound to be heard. The outer ear serves to channel the sound waves into the middle ear which is composed of three bones. These three bones mechanically transmit these waves to the oval window, which is part of the inner ear. The oval window vibrates inwardly, creating pressure waves in an incompressible fluid which fills the inner ear. This fluid pressure excites the membranes in the cochlea, a section of the inner ear shaped like a snail shell which contains the basilar membrane. The basilar membrane has tiny hair cells which transform the mechanical motion of the pressure waves into nerve impulses. These impulses are then transmitted to the brain where they are decoded and interpreted as sound.
Vibrations in the air within the external ear vibrate the tympanic membrane located between the outer and middle ears. This vibration of the tympanic membrane moves the chain of middle ear ossicles (bones). The last of the three middle ear bones (stapes) is in association with the oval window separating the middle and inner ears. The stapes bone vibrates the oval window which sets up vibrations in the perilymph that fills the osseus labyrinth of the inner ear. The vibrations of the perilymph in the scala vestibuli of the cochlea vibrates the vestibular (Reissner's membrane) creating vibrations in the endolymph filling the scala media (cochlear duct). The vibrations of the endolymph induces the basilar membrane to vibrate. The movement of the basilar membrane (upon which sits the Organ of Corti) induces the apical ends of the hair cells to interact with the tectorial membrane, depolarizing the hair cells.
