Chapter 3 The Special Senses
特殊感覺
郭進榮 Jinn-Rung, Kuo
張菁萍Ching-Ping Chang
Department of Biotechnology
Southern Taiwan University
一般感覺
感覺
特殊感覺
中樞
本體感覺
腦, 脊髓
周邊
運動
視覺傳遞路徑
17
眼睛 (eyeball)
眼球運動肌肉
視神經
1/6
視神經
Figure 15.7a, b
水晶體
後腔玻璃狀液
前腔水樣液
1.纖維層: 角膜 (Cornea), 鞏膜(Sclera)
2.血管層:
-脈絡膜 (Chloroid),
-睫狀體 (睫狀肌,睫狀突起)
-虹膜 (環狀肌,放射狀肌)
3.神經層 (視網膜)(Retina),感覺層
-視桿 (Rod).弱光視覺,夜視,區別明暗影子
-視錐 (Cone).強光視覺,彩色視覺
前房(角膜-虹膜)
後房(虹膜-水晶體)
Anterior Segment
前房(角膜-虹膜)
後房(虹膜-水晶體
Figure 15.12
Structure of the Eyeball
Figure 15.8a
Structure of the Eyeball
• A slightly irregular hollow sphere with anterior
and posterior poles
• The wall is composed of three tunics – fibrous,
vascular, and sensory
• The internal cavity is filled with fluids called
humors
• The lens separates the internal cavity into
anterior and posterior segments
Fibrous Tunic (纖維層)
• Forms the outermost coat of the eye and is
composed of:
– Opaque sclera (posteriorly)鞏膜
– Clear cornea (anteriorly) 角膜
• The sclera protects the eye and anchors
extrinsic muscles
• The cornea lets light enter the eye
Vascular Tunic (Uvea):血管層 Choroid Region
• Has three regions:
- Choroid 脈絡膜
- Ciliary body 睫狀體
- Iris 虹膜
• Choroid region
– A dark brown membrane that forms the posterior
portion of the uvea
– Supplies blood to all eye tunics
Vascular Tunic: Ciliary Body睫狀體
• A thickened ring of tissue surrounding the lens
• Composed of smooth muscle bundles (ciliary
muscles)
• Anchors the suspensory ligament懸韌帶 that
holds the lens in place
Vascular Tunic: Iris 虹膜
• The colored part of the eye
• Pupil – central opening of the iris (瞳孔)
– Regulates the amount of light entering the eye during:
• Close vision and bright light – pupils constrict
• Distant vision and dim light – pupils dilate
• Changes in emotional state – pupils dilate when the subject
matter is appealing or requires problem-solving skills
副交感
交感
Sensory Tunic: Retina視網膜
• A delicate two-layered membrane
• Pigmented layer – the outer layer that absorbs
light and prevents its scattering(色素層)
• Neural layer, which contains(神經層)
– Photoreceptors that transduce light energy
– Bipolar cells and ganglion cells
– Amacrine and horizontal cells
The Retina: Photoreceptors
• Rods: 桿細胞
– Respond to dim light (夜視)
– Are used for peripheral vision
• Cones:錐細胞(明視,彩色視覺)
– Respond to bright light
– Have high-acuity color vision
– Are found in the macula lutea
– Are concentrated in the fovea centralis
Blood Supply to the Retina
• The neural retina receives its blood supply
from two sources
– The outer third receives its blood from the choroid
– The inner two-thirds is served by the central
artery and vein
• Small vessels radiate out from the optic disc
and can be seen with an ophthalmoscope
Lens水晶體 (透明)
• A biconvex, transparent, flexible, avascular structure
that:
– Allows precise focusing of light onto the retina
– Is composed of epithelium and lens fibers
• Lens epithelium – anterior cells that differentiate into
lens fibers
• Lens fibers – cells filled with the transparent protein
crystallin
• With age, the lens becomes more compact and dense
and loses its elasticity (白內障)
Light
電磁波
可見光
400-700奈米
視網脈上不同錐細胞對
不同波長有反應
Figure 15.14
Focusing Light on the Retina
• Pathway of light entering the eye: cornea, aqueous
humor, lens, vitreous humor, and the neural layer
of the retina to the photoreceptors
• Light is refracted:
– At the cornea
– Entering the lens
– Leaving the lens
• The lens curvature and shape allow for fine
focusing of an image
Refraction and Lenses
Figure 15.16
Focusing for Distant Vision
• Light from a
distance needs
little
adjustment for
proper focusing
• Far point of
vision – the
distance
beyond which
the lens does
not need to
change shape
to focus (20 ft.)
Figure 15.17a
Focusing for Close Vision
• Close vision requires:
– Accommodation – changing the lens shape by ciliary
muscles to increase refractory power
– Constriction – the pupillary reflex constricts the pupils to
prevent divergent light rays from entering the eye
– Convergence – medial rotation of the eyeballs toward
the object being viewed
Problems of Refraction
• Emmetropic eye – normal eye with light
focused properly
• Myopic eye (nearsighted近視) – the focal
point is in front of the retina
– Corrected with a concave lens
• Hyperopic eye (farsighted遠視) – the focal
point is behind the retina
– Corrected with a convex lens
Problems of Refraction
Figure 15.18
The Ear: Hearing and Balance
.內耳 (迷路)
-耳蝸,三個半規管
-骨性迷路.
-膜性迷路
中耳.
外耳.
- 錘骨(malleus) –石占骨( Incus) –鐙骨(Stapes)
鼓膜
卵圓窗=前庭窗
耳翼, 外耳道,鼓膜
- 耳咽管,圓窗
Figure 15.25a
圖9-8
2.5cm
Outer Ear
• The auricle (pinna) is composed of:
– The helix (rim)
– The lobule (earlobe)
• External auditory canal
– Short, curved tube filled with ceruminous glands
Outer Ear
• Tympanic membrane 鼓膜(eardrum)
– Thin connective tissue membrane that vibrates in
response to sound
– Transfers sound energy to the middle ear ossicles聽小骨
– Boundary between outer and middle ears
Middle Ear (Tympanic Cavity鼓室)
• A small, air-filled, mucosa-lined cavity
– Flanked laterally by the eardrum
– Flanked medially by the oval and round windows
• Epitympanic recess – superior portion of the
middle ear
• Pharyngotympanic tube – connects the middle
ear to the nasopharynx
– Equalizes pressure in the middle ear cavity with the
external air pressure
Middle Ear (Tympanic Cavity)
耳咽管
Figure 15.25b
Fig. 9.13
聽覺器
The Cochlea
Figure 15.28
Properties of Sound
• Sound is:
– A pressure disturbance (alternating areas of high
and low pressure) originating from a vibrating object
– Composed of areas of rarefaction and compression
– Represented by a sine wave in wavelength,
frequency, and amplitude
• Frequency – the number of waves that pass a
given point in a given time
• Pitch – perception of different frequencies (we
hear from 20–20,000 Hz)
Properties of Sound
• Amplitude – intensity of a sound measured in
decibels (dB)分貝
• Loudness – subjective interpretation of sound
intensity
Figure 15.29
Transmission of Sound to the Inner Ear
Figure 15.31
聽覺傳遞路徑
聲波 -> 外耳道-> 鼓膜 -> 錘骨 ->石占骨 ->
鐙骨 ->卵圓窗 ->外淋巴液 ->耳蝸管內淋巴液
-> 毛細胞去極化 ->耳蝸神經 ->延髓耳蝸核
->中腦下丘 ->丘腦內內側膝狀體->大腦顳聽
覺區 (41, 42)
Sound and Mechanisms of Hearing
• Sound vibrations beat against the eardrum
• The eardrum pushes against the ossicles, which
presses fluid in the inner ear against the oval
and round windows
– This movement sets up shearing forces that pull on
hair cells
– Moving hair cells stimulates the cochlear nerve that
sends impulses to the brain
Transmission of Sound to the Inner Ear
• The route of sound to the inner ear follows
this pathway:
– Outer ear – pinna, auditory canal, eardrum
– Middle ear – malleus, incus, and stapes to the oval
window
– Inner ear – scalas vestibuli and tympani to the
cochlear duct
• Stimulation of the organ of Corti
• Generation of impulses in the cochlear nerve