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Chapter 1 of 10
Neurons
The signalling cell.
How they work
A neuron receives signals through dendrites, sums them, and fires an electrical impulse along its axon if a threshold is crossed. At the end, chemical messengers cross a gap to the next cell.
- Around 86 billion neurons, each connecting to thousands of others.
- The gap is the synapse, where most brain-active drugs do their work.
Glia
Non-neuronal cells insulate axons, supply nutrients, prune connections and manage immune response. Long dismissed as packing material, they are now known to shape signalling directly.