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18.6: 突触
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Biology

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Education
The Synapse
 
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18.6: 突触

神经元通过将其电信号传递给其它神经元而彼此通信。突触是两个神经元相遇以交换信号的位置。在突触处,发送信号的神经元被称为突触前细胞,而接收该消息的神经元被称为突触后细胞。请注意,大多数神经元都可以是突触前和突触后,因为它们都传输和接收信息。

电突触是一种突触,在这种突触中,突触前和突触后的细胞通过称为间隙连接的蛋白质进行物理耦合。这使得电信号可以直接传输到突触后细胞。这些突触的一个特点是,它们可以非常快速地传输电信号,有时仅需几毫秒,不需要任何能量输入。这通常在逃避行为的回路中是有用的,例如在小龙虾中发现的,它将捕食者的感觉和运动反应的激活结合起来。

相反,化学突触的传递是一个逐步的过程。当一个动作电位到达轴突末端时,电压门控钙通道打开,允许钙离子进入。这些离子触发含有神经递质的囊泡与细胞膜的融合,将神经递质释放到两个神经元之间的小空间,称为突触间隙。这些神经递质包括谷氨酸、GABA、多巴胺和5-羟色胺,然后可以与突触后细胞膜上的特定受体结合。与受体结合后,神经递质可以从突触裂处循环、降解或扩散。

化学突触在人脑中占主导地位,由于与神经递质释放有关的延迟,它比电突触具有优势。首先,一些或许多小泡可能被释放,导致多种突触后反应。其次,与不同受体的结合可能导致突触后细胞膜电位的升高或降低。此外,突触间隙中神经递质的有效性是由循环和扩散调节的。通过这种方式,化学突触可以实现神经元信号的高度调节和微调。


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Naptic Cell Initiating A Response In The Receiving Neuron. The Binding Of Neurotransmitters To Receptors Can Either Excite Or Inhibit The Postsynaptic Neuron Depending On The Specific Neurotransmitter And Receptor Involved.Once The Neurotransmitters Have Fulfilled Their Role In Transmitting The Signal They Are Either Taken Back Up Into The Presynaptic Cell Through A Process Called Reuptake Or They Are Broken Down By Enzymes In The Synaptic Cleft. This Ensures That The Signal Is Terminated And Allows For Precise Control Of Neuronal Communication.The Synapse Is A Crucial Component Of Neural Communication Allowing For The Transmission Of Information Between Neurons. It Plays A Vital Role In Processes Such As Learning Memory And Coordination Of Bodily Functions. Understanding The Functioning Of Synapses Is Essential In Unraveling The Complexities Of The Nervous System And Developing Treatments For Neurological Disorders

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