Читать книгу Neurobiology For Dummies - Frank Amthor - Страница 97

Neurons use electricity to communicate between different parts of the same neuron and between neurons. How this works is one of the most fascinating stories in all science.

The story starts with transporter pumps (refer to “Talking about transporters,”earlier in this chapter) in the membrane that create ionic imbalances between the inside and outside of the cell. Not all ions get to move through the membrane, and the ligand-gated and voltage-gated channels act as the membrane’s “bouncers,” allowing only specific ions to move through. Then, voltage-gated channels amplify the effects caused by ligand binding so that distant parts of the cell’s dendritic tree communicate these events to the cell’s soma. The cell’s soma then communicates the dendritic events to the axon terminal, which releases neurotransmitters that affect other neurons, and the symphony of brain activity plays on.

Believe it or not, every neuron in your body is actually a little battery that can make electric current flow. Think of the regular batteries you use every day. In these manmade batteries, chemical reactions in an electrolyte (salt solution) cause electrons to flow in an external circuit between two different electrodes that are immersed in the electrolyte.

You can think of neurons in the same way. In neurons, ions in solution such as sodium, potassium, or chloride move through specific channels in the membrane when these channels are opened by ligands or electric fields (voltage). The reasons for ions moving through membrane channels are diffusion (concentration differences between inside and outside) and voltage differences between the inside and outside. The continuous running of the transporter pumps maintains these concentration differences — or ionic imbalances.