北大神经生物学课件4-1神经元的信息传递

突触的分类
Gray Ⅰ型 Ⅱ型
按突触膜的特征分类
Colonnier 不对称型
对称型
按突触小泡的形态分类(Uchizon&Bodian)
S型
F型
按突触功能分类
兴奋型
抑制型
神经递 质(Neurotransmitter)
—在化学性突触传递过程中起信息传递作用的化学物质
神经递质的判定标准（ Criteria for neurotransmitter）
递质的分类(Categories of neurotransmitters)
经典神经递质(Classical neurotransmitters) 》 神经肽(Neuropeptides) 》 其它类型
• • • NO、CO 组织胺(Histamine) 腺苷(ATP)》
Chemical Synapse
20 - 40 nm
3.5 nm
Yes
No Presynaptic vesicles and
Ultrastructural components
Βιβλιοθήκη Baidu
Gap-iunction channels
active zones; postsynaptic receptors Chemical transmitter Significant:at least 0.3 ms, usually 1- 5 ms or longer
Synaptic transmission at chemical synapses involves several steps
Neurotransmitters act either directly or indirectly on ion channels that regulate current flow in neurons
Electrical Synapses
Gap-Junction Channels Connect Communicating Cells at an Electrical Synapse Electrical Transmission Allows the Rapid and Synchronous Firing of Interconnected Cells Electrical Synapses Provide Instantaneous Signal Transmission
Ligand-gate Ion Channel Receptors G-protein coupled Receptors (Second-Messenger Pathways) Tyrosine Protein Kinase Receptors

Open or Close of Postsynaptic Ion Channels － Postsynaptic Potentials －Action Potentials of Postsynaptic cell
Electrical Synapses are bidirectional
Return
Fig. 2
Distinguishing Properties of Electrical and Chemical Synapses
Electrical Synapse
Distance between pre- and postsynaptic cell membranes Cytoplasmic continuity between pre- and postsynaptic cells
突触前神经元存在合成递质的前体和酶体系，并能合 成该递质
递质存在突触小泡内，当冲动抵达末梢时，小泡内递 质能释放入突触间隙
递质释出后经突触间隙作用于后膜上特异受体而发挥 其生理效应 存在使该递质失活的酶或其他方式(如重摄取) 有特异的受体激动剂或拮抗剂，并能够分别拟似或阻 断该递质的突触传递作用
Chemical Synapses
How do Signals from Pre-synaptic Cell Transmit to Post-synaptic Cell ? － Electrical-Chemical-Electrical Signals Transform


神经元之间的信息传递
(Synaptic Transmission Between Neurons)
薛冰
北京大学神经科学研究所
神经元之间信息传递的方式
神经元最主要的功能是通过突触(Synapse)进行细胞间的信息传递 突触有电突触(Electrical Synapse)和化学性突触(Chemical Synapse)， 但以化学性突触为主
电突触通过缝隙连接(gap junction)直接完成细胞间的电信息传递Fig.1
化学性突触传递必须依赖于神经递质(Neurotransmitters)或神经肽 (Neuropeptides)作用于突触后膜的受体而完成细胞间的信息传递Fig.2
Fig. 1
Current flows at electrical synapse
Releases of Chemical Transmitters from Pre-synaptic Membrane Chemical Transmitters Bind to Postsynaptic Receptors
Postsynaptic Receptors Gate Ion Channels Either Directly or Indirectly
Agent of transmission
Ion current Virtually absent
Synaptic delay
Direction of transmission
Usually bidirectional
unidirectional
Current flows differently at electrical and chemical synapses