1、Chapter 9Function of the Sense OrgansSensation requires:Stimulusreceptors（sense organs）afferent nerve cortexspecial sense Sensation2.Physiology of the receptorsSection 1 Physiology of the receptor and sense organs1.Concept and classification of the receptors and sense organs1.Concept and classificat
2、ion of the receptor and sense organsReceptor:a structure which,on receiving environmental stimuli,produces an informative nerve impulse.Sense organ:a specialized organ or structure,such as the eye,ear,tongue,nose,or skin,where sensory neurons are concentrated and that functions as a receptor.Which r
3、eceptor?Classification of receptorsGeneral sensory receptor structureEach type of receptor is highly sensitive to one type of stimulus for which it is designed and yet is almost nonresponsive to normal intensities of other type of stimuli.2.Properties of the receptors(1)Adequate stimulus(适宜刺激适宜刺激)(2
4、)Transducer functionSense organs transduce sensory energy into neural(bioelectrical)energy.Receptor potentials(感受器电位感受器电位):Changes in the transmembrane potential of a receptor caused by the stimulus Generator potential(发生器电位发生器电位):A receptor potential that is strong enough(reaches threshold)to gener
5、ate an action potential.The quality of the stimulus is encoded in the frequency of the action potentials transmitted down the afferent fibre and the number of sensory receptors activated.1)1)感觉性质的编码感觉性质的编码 决定于刺激的性质、决定于刺激的性质、感受器种类和传入冲感受器种类和传入冲动所到达的动所到达的高级中枢高级中枢的部位的部位，而不是取决，而不是取决于动作电位的波形或于动作电位的波形或序列特性
6、的差别。序列特性的差别。(3)Encoding of sensory receptor单一神经纤维动作电位频率；单一神经纤维动作电位频率；参与传递信息的神经纤维数目。参与传递信息的神经纤维数目。Stretch Receptors:Weak stretch causes low impulse frequency on neuron leaving receptor.Strong stretch causes high impulse frequency on neuron leaving receptor.2)感觉强度的编码感觉强度的编码蛙肌梭中刺激强度的编码模式图蛙肌梭中刺激强度的编码模式图
7、1)Definitions:refers to a progressive decrease in firing frequency despite maintained depolarization.(4)Adaptation of sensory receptor2)Types:Rapidly adapting receptor:pacinian and hair receptors detect the change in stimulus strength(detect movement).Slowly adapting receptor:joint capsule,muscle sp
8、indle detect continuous stimulus strength(give report to the brain about the status of the body).Section 3 The Visual Organ 1.Refractive media of eye and its accommodation(1)Refractive systemstructure of the eyeballCornea Aqueous humorLens VitreousThe human eye is similarly a complex structure and f
9、or many purposes an idealized model eye,the reduced eye,introduced by Donders,is very useful.The several refracting surfaces are replaced by one ideal surface at an air/water interface 20mm from a model retina.This converts a system with 6 cardinal points into one with three.(2)Reduced eye(3)Accommo
10、dation of the eye 6 mAccommodation of the eye:Accommodation of lens Accommodation of pupil Convergence1)Accommodation of lensCiliary muscle contractLens zonule relaxAccommodationElastic deformation of lensSee near视近物时，晶状体调视近物时，晶状体调节的神经反射过程：节的神经反射过程：视网膜上模糊物像视网膜上模糊物像 视区皮层视区皮层中中脑的脑的正中核正中核 动动眼神经副交感核团眼神经
11、副交感核团 睫状神经睫状神经 睫状肌的环行肌收睫状肌的环行肌收缩缩 悬韧带松弛悬韧带松弛 晶状体变凸晶状体变凸,使使辐散光线聚焦在视辐散光线聚焦在视网膜上。网膜上。The nearest point at which an object can be seen distinctly by the eye 10 10 岁岁 8.3 cm 8.3 cm 20 20 岁岁 11.8 cm11.8 cm 60 60 岁岁 83.3 cm83.3 cm新生儿新生儿 成年人成年人 老人老人Near point(近点近点)Presbyopia is a condition where,with age,th
12、e eye exhibits a progressively diminished ability to focus on near objects.Presbyopia(老视老视)pupillary near reflex：When fixation of the eye is shifted from a far to a near object,both pupils constrict.2)Accommodation of pupilPupil diameter:1.5-8.0 mmPathway It is a reflex that controls the diameter of
13、 the pupil,in response to the intensity(luminance)of light that falls on the retina of the eye,t h e re b y a s s i s t i n g i n adaptation to various levels of darkness and light,in a d d i t i o n t o r e t i n a l sensitivity.Pupillary light reflex：3)Convergence（双眼球会聚）（双眼球会聚）Convergence is the a
14、bility of the eye to simultaneously demonstrate inward movement of both eyes toward each other.This is helpful in effort to make focus on near objects clearer.(4)Error of RefractionEmmetropia(正视眼正视眼)：the refractive condition in focus on fovea that parallel lights enter eye through refractive system
15、without accommodationAmetropia(非正视眼非正视眼)：the refractive condition out of focus on fovea that parallel lights enter eye through refractive system on static refractionClassification:myopia hyperopia astigmatism1)Myopia(近视近视)Axis myopia：眼球前后径过长眼球前后径过长 Refractive myopia：折光能力过强：折光能力过强 Axis hyperopia：眼球前后
16、径过短眼球前后径过短 Refractive hyperopia：折光能力太弱：折光能力太弱2)Hyperopia(远视远视)The refractive status that parallel lights cant focus through refractive system on static refraction because efractive power of individual meridian is different.3)Astigmatism(散光散光)a.Nearsightedness(myopia)b.Farsightedness(hyperopia)normal
17、eyeballLong eyeball;rays focus in front ofretina when viewing distant objects.Concave lens allows subjectto see distant objects.Convex lens allows subjectto see close objects.Short eyeball;rays focus behindretina when viewing close objects.normaleyeballUneven cornea;rays do not focus evenly.c.Astigm
18、atismUneven lens allows subjectto see objects clearly.(5)Aqueous humor(房水房水)Ciliary body Posterior chamber Anterior chamber Sinus venosus sclera Anterior ciliary vein Ophthalmic veinIridocorneal angle Pupil 2.眼的感光换能系统眼的感光换能系统Fibrous Tunicto optic nervesclerachoroidretinachoroida.Location of retinab.
19、Micrograph of retinalight raysaxons ofganglion cellsblindspotopticnerveganglioncell layerbipolarcell layerrod celland conecell layer(1)Organization of the retina(视网膜视网膜)Rods and Cones视杆细胞和视锥细胞视杆细胞和视锥细胞视杆细胞外段的超微结构视杆细胞外段的超微结构 视杆系统（视杆系统（晚光觉或暗视觉晚光觉或暗视觉)视锥系统视锥系统（昼光觉或明视觉）（昼光觉或明视觉）视锥细胞系统视锥细胞系统视杆细胞系统视杆细胞系统分
20、布分布中央凹及黄斑处密集中央凹及黄斑处密集偏中央凹偏中央凹6mm6mm处最密处最密突触联系突触联系视锥视锥-双极双极-神经节细胞神经节细胞视杆视杆-双极双极-神经节细胞神经节细胞联系特点联系特点单线式联系单线式联系汇聚式联系汇聚式联系功能特点功能特点对光的敏感度较低对光的敏感度较低对光的敏感度较高对光的敏感度较高感受强光感受强光感受弱光感受弱光对被视物细节分辨能力较高对被视物细节分辨能力较高分辨能力低分辨能力低负责明视觉和色觉负责明视觉和色觉负责暗视觉，无色觉负责暗视觉，无色觉感光色素感光色素视红质、视绿质和视蓝质视红质、视绿质和视蓝质视紫红质视紫红质（2）视网膜的两种感光换能系统）视网膜的两
21、种感光换能系统两种感光换能系统存在的依据两种感光换能系统存在的依据：1）人视网膜中视杆和视锥在空间上的分布不均匀）人视网膜中视杆和视锥在空间上的分布不均匀2）两种感光细胞和双极细胞以及节细胞形成信息传递）两种感光细胞和双极细胞以及节细胞形成信息传递通路时，其联系方式有所不同通路时，其联系方式有所不同3）不同动物视网膜的感光细胞构成不同。）不同动物视网膜的感光细胞构成不同。4）视杆细胞只有一种视色素，视锥细胞含有三种视色素，视杆细胞只有一种视色素，视锥细胞含有三种视色素，这与视杆细胞无色觉功能而视锥细胞有色觉功能吻合。这与视杆细胞无色觉功能而视锥细胞有色觉功能吻合。1）视紫红质的光化学反应）视紫
22、红质的光化学反应（3）视杆细胞的感光换能机制）视杆细胞的感光换能机制Rhodopsin cycle视蛋白视蛋白视黄醛视黄醛视紫红质视紫红质全反型视黄醛全反型视黄醛感受器电位感受器电位11-11-顺视黄醛顺视黄醛2）视杆细胞的感受器电位）视杆细胞的感受器电位-30-40mV暗电流暗电流磷酸二脂酶磷酸二脂酶150种颜色(4)(4)视锥系统的换能和颜色视觉视锥系统的换能和颜色视觉380760三原色学说三原色学说在视网膜中存在分别对红、绿和蓝光敏感的三种视锥细胞，分在视网膜中存在分别对红、绿和蓝光敏感的三种视锥细胞，分别含有视红质、视绿质和视蓝质为其感光色素，当不同波长的别含有视红质、视绿质和视蓝质为
23、其感光色素，当不同波长的光线入眼时，这三种视锥细胞的兴奋程度不同，在中枢则产生光线入眼时，这三种视锥细胞的兴奋程度不同，在中枢则产生各种不同的颜色色觉。各种不同的颜色色觉。光谱吸收曲线光谱吸收曲线视锥细胞与视杆细胞换能的异同：视锥细胞与视杆细胞换能的异同：相同点：相同点：都是超极化型感受器电位都是超极化型感受器电位 感光换能的机制十分相似感光换能的机制十分相似不同点：不同点：视锥细胞感光色素分子数目少视锥细胞感光色素分子数目少 视锥细胞有三种感光色素并且分别对映三种视锥细胞视锥细胞有三种感光色素并且分别对映三种视锥细胞 视锥细胞的三种感光色素彼此之间以及与视紫红质之视锥细胞的三种感光色素彼此之
24、间以及与视紫红质之间均不同，但不同点仅在于间均不同，但不同点仅在于视蛋白分子视蛋白分子的不同的不同Color blindness(色盲色盲)左：正常颜色视觉；右：全色盲左：正常颜色视觉；右：全色盲左：红色弱；右：红色盲左：红色弱；右：红色盲左：绿色盲；右：蓝色盲左：绿色盲；右：蓝色盲 Colour blindness results when there is a deficiency in one or more of the cone colors（1）暗适应和明适应）暗适应和明适应Dark adaptation(暗适应暗适应)：increased sensitivity of rods
25、and cones in darknesse.g.,entering a darkened roomCones:adapt for 10 minutes but never become very sensitiveRods:continue adapting for 30 minutes and become much more sensitive机制：暗处视紫红质的合成大于分解，视紫红质的量增机制：暗处视紫红质的合成大于分解，视紫红质的量增多多 3.与视觉有关的生理现象与视觉有关的生理现象7视锥细胞色素合成量增加视锥细胞色素合成量增加视杆细胞色素合成量增加视杆细胞色素合成量增加When o
26、ne passes suddenly from a dim to a brightly lighted environment,the light seems intensely and even uncomfortably bright until the eyes adapt to the increased illumination and the visual threshold rises.机制：暗处视紫红质大量蓄积，到明亮处大量而机制：暗处视紫红质大量蓄积，到明亮处大量而迅速分解，产生耀眼的光感；待视紫红质分解后，迅速分解，产生耀眼的光感；待视紫红质分解后，对光敏感度低的视锥细胞的
27、感光色素开始发挥作对光敏感度低的视锥细胞的感光色素开始发挥作用，视力恢复。用，视力恢复。Light adaptation(明适应明适应)：（2）Visual field(视野视野)单眼固定不动注单眼固定不动注视前方某点时，视前方某点时，该眼所能看到的该眼所能看到的空间范围空间范围 眼分辨细小结构的能力。衡量标准：以人能看清最小视网眼分辨细小结构的能力。衡量标准：以人能看清最小视网膜像为标准。膜像为标准。常用视力表常用视力表的类型的类型 Snellen氏视力表氏视力表 Landolt氏视力表氏视力表（3）Visual acuity（视力）（视力）Section 4 Auditory senseF
28、requency Range of hearing of the human ear16-20000Hz。听阈听阈：对于一种频率的声波，人能听到的最低声强。：对于一种频率的声波，人能听到的最低声强。最大可听阈最大可听阈：当振动强度增加，引起听觉和鼓膜的疼痛感觉，：当振动强度增加，引起听觉和鼓膜的疼痛感觉，这个限度称为最大可听阈。这个限度称为最大可听阈。人的正常听阈图人的正常听阈图语言频率语言频率听阈听阈最大可听阈最大可听阈Hearing threshold1.Function of middle earMalleus(锤骨锤骨)Incus(砧骨砧骨)Stapes (镫骨镫骨)Auditory
29、ossicles(听小骨听小骨)Pathway of sound wave Sound waves movement of tympanic membrane movement of malleus movement of incus movement of stapes movement oval window movement of fluid inside the cochlea movement of round window2.内耳的功能内耳的功能(1)Structure of the ear(2)耳蜗的感音换能作用耳蜗的感音换能作用 1)Vibration of basilar m
30、embrane and the traveling wave theory(行波学说行波学说)卵圆窗膜卵圆窗膜圆窗膜圆窗膜Traveling wave theorySound wave entering at the oval window is to cause the basilar membrane at the base of the cochlea to vibrate Different frequencies cause vibrations at different locations(places)along basilar membraneHigher frequencie
31、s at base,lower frequencies at top2)Hair cell excitation and receptor potential基底膜和盖膜振动时毛基底膜和盖膜振动时毛细胞顶部纤毛受力情况细胞顶部纤毛受力情况(3)Electrical phenomena in the cochleaHair cells Resting membrane potential-70 mVEndocochlear potential(Endolymphatic potential):+80mVMicrophonic potential(微音器电位微音器电位)Action potenti
32、alMechanism of hair cell excitationEP is the positive voltage of 80-100 mV seen in the endolymphatic space in the scala media of the cochlea1)The endocochlear potential(EP,耳蜗内电位耳蜗内电位)K+,Na+,Ca2+-80 mV-80 mVReticular Lamina+80 mV+80 mVlIntracellular potential(IP)or organ of corti potential(resting po
33、tential)Recorded-80 mV inside cells of organ of corti2)Cochlear microphonic potential(CM,耳蜗微音耳蜗微音器电位）器电位）当耳蜗受声音刺激时，在耳蜗及当耳蜗受声音刺激时，在耳蜗及其附近结构可记录到一种特殊的其附近结构可记录到一种特殊的电波动，其波形与作用于耳的声电波动，其波形与作用于耳的声波振动形式相类似，波幅随刺激波振动形式相类似，波幅随刺激的强度而变化。的强度而变化。（耳蜗能像微音器那样将声波振动转变（耳蜗能像微音器那样将声波振动转变成相应的音频电信号，故称微音器电成相应的音频电信号，故称微音器电位。）位。）特点：特点：没有潜伏期和不应期没有潜伏期和不应期;不易疲劳、不发生适应现象不易疲劳、不发生适应现象;在听阈范围内，它能重复声波的频率；在听阈范围内，它能重复声波的频率；对缺氧和深麻醉相对不敏感，在听神经变性时仍对缺氧和深麻醉相对不敏感，在听神经变性时仍能出现能出现;关于它的产生原理还不十分清楚。关于它的产生原理还不十分清楚。听觉产生的过程听觉产生的过程
