07 神经组织-Nervous tissue幻灯片.pptVIP

有髓和无髓神经纤维的比较 形成方式 结构特征 传导快慢 绝缘性能 传导特点的区别 myelinated nerve fiber ：跳跃式，故速度快。 unmyelinated nerve fiber ：无髓鞘和郎飞结，故其传导为非跳跃式，速度慢。 Schwann cell nerve fiber 由神经纤维和结缔组织构成 epineurium perineurium endoneurium 神 经 Nerve 五、Nerve Ending Sensory nerve ending Motor nerve ending ㈠ Sensory nerve ending 1. 游离神经末梢free nerve ending 2. 触觉小体tactile corpuscle 4. 肌梭muscle spindle 3. 压觉小体pressure sense 1. Free nerve ending 分布：表皮、角膜、各种结缔组织 功能：感受冷、热、轻触和痛觉刺激 游离神经末梢 分布： 功能： 2. Tactile corpuscle 真皮乳头，于手指最多 感受应力刺激，参与产生触觉 触觉小体 3. Lamella corpuscle 分布： 皮下组织、腹膜、肠系膜、韧带、关节囊等处 功能： 感受较强的应力，参与产生压觉和振动觉 环层小体 4. Muscle spindle 分布：骨骼肌内 功能： 为本体感受器，感受骨骼肌的舒缩状态，参与调节骨骼肌活动 肌梭 1. Somatic motor nerve ending LM：轴突终末失去髓鞘，呈爪状分支，末端贴于骨骼肌表面，形成椭圆形板状隆起，称运动终板motor end plate。 ㈡ Motor nerve ending 运 动 终 板 系突触结构，但间隙较宽，40~60nm 后膜凹陷成槽状 神经递质为乙酰胆碱，引发骨骼肌收缩 EM： 电镜下可见肌纤维表面浅槽，又凹陷许多深沟和皱褶，轴突终末嵌于槽内形成突触样结构。 　　一个运动神经元的的轴突及其分支所支配的全部骨骼肌纤维全称一个运动单位。 2. Visceral motor nerve ending 无髓神经纤维末梢呈串珠状膨突，内含突触小泡synaptic vesicle，与平滑肌或腺细胞表面接触，引发其收缩或分泌。 Nerve Regeneration Following Injury Main changes that take place in an injured nerve fiber. A: Normal nerve fiber, with its perikaryon and effector cell (striated skeletal muscle). Note the position of the neuron nucleus and the quantity and distribution of Nissl bodies. B: When the fiber is injured, the neuronal nucleus moves to the cell periphery, and Nissl bodies become greatly reduced in number. The nerve fiber distal to the injury degenerates along with its myelin sheath. Debris is phagocytosed by macrophages. C: The muscle fiber shows a pronounced denervation atrophy. Schwann cells proliferate, forming a compact cord penetrated by the growing axon. The axon grows at the rate of 0.5—3 mm/day. D: Here, the nerve fiber regeneration was successful. Note that the muscle fiber was also regenerated after receiving nerve stimuli. E: When the axon does not penetrate the cord of Schwann cells, its growth is not organized. * 21、21-1、21-2 * 21、21-1、21-2 * 21 联系有机磷农药中毒等 * Local changes Severed en