内容讲义07nervous tissue中英

1、NERVOUS TISSUE神经组织Histology. General Characteristics A. Made up of 2 types of cells: neurons -神经元structural and functional unit; neuroglia -神经胶质细胞supporting, protecting and nourishing neurons.B. Neurons 神经元Unique processes; Forming synapses; Conducting impulses.C. Making up nervous system: CNS - bra

2、in and spinal cord; PNS - ganglia, nerves.D. Function: integrating and coordinating body activities. Neurons 神经元 Various shape and size, Cell body 胞体processes 突起.A. Cell body:胞体 metabolic, tropic and integral center 1. Nucleus细胞核 large, spherical, and pale-staining; a prominent nucleolus.核仁2. Perika

3、ryon 核周质- perinuclear cytoplasm a. Nissl bodies 尼氏体 Basophilic particles, RER + free ribosomes, Indicating active protein synthesis.合成复制细胞器所需的结构蛋白、合成神经递质所需的酶类b. Neurofibrils 神经原纤维 Thin threads with silver staining; Neurofilaments and microtubules; Cytoskeleton, transportation of substances.构成神经元的细胞骨

4、架，微管还参与物质运输细胞膜：含受体、离子通道，为可兴奋膜，接受刺激、处理信息、产生并传导神经冲动B. Processes 突起- dendrites and axons 1. Dendrites 树突 One or more /neuron; Usually short and thick, and branched; Dentritic spines on surfaces;棘突 Containing Nissl bodies;树突内胞质的结构与胞体相似Receiving information and conducting it to parent cell body.2. Axon 轴

5、突 One axon each neuron; Long and thin, does not branch profusely; Derived from axon hillock轴丘; axolemma轴膜; axoplasm轴质 Devoid of Nissl bodies; Axon terminals轴突终末(buttons) contain vesicles with neurotransmitters神经递质in them; Conduct impulses away from cell body. 慢速轴突运输：胞体内形成的神经丝、微丝和微管缓慢向轴突终末延伸快速顺向轴突运输：

6、由胞体向轴突终末快速输送蛋白质、酶、含神经调质的小泡等快速逆向轴突运输：轴突终末的代谢产物、或由轴突终末摄取的物质、病毒或毒素运输到胞体C. Classification 分类1. According to number of processes Pseudounipolar假单极神经元: found in spinal ganglia; Bipolar双极神经元: present in cochlear and vestibular ganglia, retina, olfactory, etc; Multipolor多极神经元: majority of neurons. 2. Accord

7、ing to function Sensory感觉神经元or afferent传入神经元; Motor运动神经元or efferent传出神经元; Interneurons中间神经元: account for 99% of neurons in the body.3. According to neurotransmitter神经递质released Cholinergic胆碱能神经元: acetylcholine (Ach); Aminergic胺能神经元: norepinephrine (NE), DA, 5-HT; Peptidergic肽能神经元: polypeptides such

8、as substance P, vasopressin, etc. III. Synapses 突触A. Definition:Junction between two neurons or between a neuron and an effector cellspecialized for transmission of impulses. 神经元与神经元之间、神经元与效应细胞之间传递信息的部位最常见一个神经元的轴突终末与另一个神经元的树突、树突棘或胞体连接，分别形成轴-树、轴-棘或轴-体突触B. Classification 1. Electrical synapses: permit

9、 direct flow of electrical current between two neurons (gap junction). 2. Chemical synapses化学突触: use a chemical mediator (neurotransmitter) to transmit impulses in one direction;C. Structure of chemical synapses Synaptic boutons银染色扣结状Presynaptic elementSynaptic cleftPostsynaptic element1. Presynapti

10、c element 突触前成分Usually axon terminal; Synapticvesicles突触小泡,表面附有突触素，连接小泡与细胞骨架，Mit, SER, Mt, Mf; Presynaptic membrane 突触前膜 thickened with presynaptic grid, dense projections.含钙离子通道Clear vesicles Ach; dense core vesicles Amines, peptidesDense projections2. Synaptic cleft 突触间隙Extracellular space between

11、 pre- and postsynaptic membranes.3. Postsynaptic element 突触后成分 Usually dendrite (or spine) or cell body; Postsynaptic membrane 突触后膜thickened Receptors to the neurotransmitter. transmitting impulses in one direction 当神经冲动沿轴膜传至轴突终末时，即触发突触前膜上的电位门控钙通道开放.细胞外的Ca2进入突触前成分，在ATP的参与下使突触素发生磷酸化,促使突触小泡移附在突触前膜上，通过

12、出胞作用释放小泡内的神经递质到突触间隙内。其中部分神经递质与突触后膜上相应受体结合，引起与受体偶联的化学门控通道开放，使相应离子进出，从而改变突触后膜两侧离子的分布状况，出现兴奋或抑制性变化，进而影响突触后神经元（或非神经细胞）的活动。使突触后膜发生兴奋的突触称兴奋性突触（excitatory synapse），使突触后膜发生抑制的称抑制性突触（inhibitory synapse）。突触的兴奋或抑制，取决于神经递质及其受体的种类。. Neuroglia 神经胶质细胞A. General features 1. More than neurons by 5 -10 times;2. With

13、processes, but not conduct impulses;3. Only nuclei seen with Nissl stains. Silver staining shows processes and cytoplasm;4. Can divide after birth;B. Neuroglia in CNS1. Astrocytes 星形胶质细胞 Most numerous; oval, pale staining nucleus; Many processes: fibrous 纤维型 白质protoplasmic;原浆型 灰质 Support & separate

14、neurons, repair, secrete NTF, blood-brain barrier etc; blood-brain barrier 血-脑屏障 endothelial cells with tight junctions;连续毛细血管的内皮（细胞间有紧密连接） continuous basal lamina;连续基膜 vascular feet of astrocyte processes.星形胶质细胞形成的脚板(神经胶质膜)阻止血液中某些物质进入脑，选择性允许营养和代谢产物通过，维持脑内环境稳定2.OligodendrocytesSmaller with a round,

15、dark-staining nucleus;Forming myelin sheath 髓鞘 around axons in the CNS. 少突胶质细胞中枢神经系统的髓鞘形成细胞3. Microglia 小胶质细胞 smallest with a irregular, darkly stained nucleus; Phagocytic; 吞噬作用 Derived from monocytes. 来自单核细胞4. Ependymal cells 室管膜细胞 columnar or cuboidal epithelioid cells; lining ventricles of brain

16、and central canal of spinal cord.衬在脑室和脊髓中央管的腔面，形成单层上皮，即室管膜，参与产生脑脊液C. Neuroglia in PNS 1. Schwann cells 施万细胞 Forming myelin sheath around axons in PNS;形成周围神经系统神经纤维的髓鞘 Secreting neurotrophic factors (NGF, BDNF). 分泌神经营养因子A layer of flattened or cuboidal cells; Forming capsule around neurons in peripher

17、al ganglia. 神经节内包裹神经元 胞体的一层扁平或 立方形细胞2. Capsular cells (satellite cells)被囊细胞 or 卫星细胞. Nerve Fibers 神经纤维A. Myelinated nerve fibers 有髓神经纤维 in PNS 1. Basic structure Axon + myelin sheath + neurolemma; 轴突 + 髓鞘 + 神经膜Node of Ranvier 郎飞结 Portions devoid of myelin sheath; Internode 结间体between2 consecutive no

18、des - one Schwann cell.2. Myelin sheath 髓鞘a. LM:sponge like (H & E),Black (OsO4).b. EM: concentric lamellae. c. Incisures of Schmidt-Lanterman: 髓鞘切迹cone-shaped clefts (contain cytoplasm).为内、外侧胞质间的狭窄通道d. Formation:Schwann cell plasmalemma winding around axon many times. 3. Neurolemma 神经膜Outermost lay

19、er of cell membrane of Schwann cells and basai lamina. B. Myelinated nerve fibers in CNS Similar to Myelinated nerve fibers in PNS;Myelin sheath is formed by processes of oligodendrocytes.少突胶质细胞形成髓鞘，一个少突胶质细胞有多个突起可分别包卷多个轴突，其胞体位于神经纤维之间 No neurolemma, no incisures of Schmidt-Lanterman;神经纤维外表面无基膜，髓鞘内无切迹

20、C. Unmyelinated nerve fibers 无髓神经纤维1. PNS No myelin sheath and nodes of Ranvier. Thin axons (single or group) indented into Schwann cells; 施万细胞为不规则的长柱状，表面有数量不等、深浅不同的纵行凹沟，纵沟内有较细的轴突，施万细胞的膜不形成髓鞘。 一条无髓神经纤维可含多条轴突。 由于相邻的施万细胞衔接紧密，无郎飞结。2. CNSFree axons among other neuronal and glial processes 轴突外面没有特异性的神经胶质

21、细胞包裹，轴突裸露地走行于有髓神经纤维或神经胶质细胞之间D. Functional role1. Unmyelinated nerve fibers continuous conduction无髓神经纤维的神经冲动沿轴膜连续传导，故传导速度慢 Enhancing conduction speed via saltatory conduction; Thicker axon thicker myelin sheath and longer internode greater conduction velocity.2. Myelinated nerve fibers:有髓神经纤维的神经冲动在郎飞

22、结间呈跳跃式传导，故传导速度快A. Nerves 神经- Made up of nerve fibers and connective tissue. Nerve and nerve endings1. Nerve fibersMixed - both myelinated and unmyelinated, sensory and motor. Epineurium:神经外膜Fibrous Ct enclosing entire nerve; Perineurium:神经束膜Sheet of flattened epithelium-like cells surrounding each n

23、erve bundles; Endoneurium:神经内膜Thin layer of LCt enveloping each nerve fiber. EpPe2. Connective tissueEp1. Classification(1) Sensory (receptors)(2) Motor (effectors)B. Nerve endings 神经末梢a. Free nerve endingsb. Encapsulated nerve endings Tactile corpuscles Lamellated corpuscles Muscular spindlesa. Som

24、atic (motor end plate)b. Visceral 感觉神经末梢运动神经末梢2. Free nerve endings 游离神经末梢 Abundant in epidermis, cornea, hair follicles; Branches of naked nerve fibers; Responding to cold, heat and pain.3. Tactile (Meissner) corpuscles 触觉小体 Found in dermal papillae; Touch receptors; Oval bodies with flattened cell

25、s, CT capsule and nerve terminal(s).4. Lamellated (Pacinian) corpuscles 环层小体 Distributed in subcutaneous tissue, mesentery; Perceiving pressue and vibration; Composed of concentric lamellae of flattened cells, an internal cylinder, and naked nerve fiber terminal(s). 5. Muscular spindles 肌梭 Distribut

26、ed in skeletal muscle; Formed by CT capsule, intrafusal muscle fibers (thin, striated, nuclei arranged in chain or cluster); Nerve fibers end as annulospiral or flower-spray endings; Proprioceptors:本体感受器 detecting muscle length and its changes to regulate muscle tone. 6. Motor end plate (myoneural j

27、unction) 运动终板（神经肌连接） Synapse between motor nerve terminals and skeletal muscle fibers causing muscle contraction; LM: Nerve fibers ramify with each terminal dilating as a plate like mass touching a muscle fiber; EM: Presynaptic element (axon terminal) vesicles containing Ach, postsynaptic membrane (

28、sarcolemma) N receptors for Ach.7.Visceral motor nerve ending 内脏运动神经末梢分布：心肌,内脏及血管平滑肌,腺体结构：无髓神经纤维分支末段呈串珠样膨体，贴附于细胞表面或穿行于细胞之间，与细胞建立突触功能：控制或调节肌细胞收缩、腺体分泌Nervous System 神经系统Central nervous system CNS Brain Spinal cord Periphery nervous system PNS cranial and spinal ganglia cranial and spinal nerve autonom

29、ic ganglia autonomic nerve Central nervous system gray matter- cortex white matter-medulla功能：通过神经元及其突触建立的神经网络直接或间接调控机体各系统、器官的活动，对体内、外各种刺激作出迅速而完善的适应性反应Spinal cord 脊髓Gray matter anterior horn lateral horn posterior hornWhite matter nerve fiber bundles脊髓灰质前角：含躯体运动神经元 运动神经元：胞体大，轴突粗，分布于骨骼肌，神经递质为乙酰胆碱 运动神经

30、元：胞体小，轴突细，支配梭内肌纤维，神经递质为乙酰胆碱 闰绍细胞：小，短轴突与运动神经元形成突触，释放甘氨酸抑制后者的活动侧角：含内脏运动神经元（胆碱能）后角：神经元类型复杂，主要接受感觉神经元轴突传入的神经冲动脊髓的功能：传导上、下行神经冲动和反射活动Cerebral cortex大脑皮质神经元数量大、种类多、均为多极神经元锥体细胞: 大、中、小型，轴突组成投射纤维，发向脑干或脊髓，或联合传出纤维，发向大脑皮质同侧或对侧的其它区域；传出信息。颗粒细胞: 水平细胞、星形细胞、篮状细胞、上行轴突细胞；小，构成局部神经环路梭形细胞：分布在皮质浅层，属投射神经元 molecular layer 分子

31、层神经元少，主要为水平细胞和星形细胞；神经元的突起和其它神经纤维与表面平行 external granular layer 外颗粒层:大量星形细胞和少量小型锥体细胞 external pyramidal layer外锥体细胞层:厚, 大量中、小型锥体细胞；树突伸至分子层，轴突组成联合传出纤维 123456 internal granular layer内颗粒层:大量星形细胞 internal pyramidal layer内锥体细胞层:大、中、大型锥体细胞；轴突下行到脑干和脊髓组成投射纤维 polymorphic layer多形细胞层:梭形细胞为主, 还有锥体细胞、星形细胞；梭形细胞树突伸至分子层，轴突组成投射纤维或联合传出纤维12345614层的神经元与联合传入纤维形成突触，接受信息5、6层的锥体细胞和大梭形细胞的轴突组成投射纤维，发向脑干或脊髓3、5、6层的锥体细胞和梭形细胞的轴突组成联合传出纤维，发向大脑皮质同侧或对侧的其它区域 Cerebellar cortex 小脑皮质1. Molecular layer 分子层 较厚，含大量神经纤维 神经元少而分散，包括星形细胞和篮状细胞 星形细胞：位于浅层，小而多突起，轴突与蒲肯野细胞形成突触 篮状细胞：位于深层，大，