The chemical synapse, on the other hand, is unique to the nervous system of higher mammals and requires the intermediation of hormones to distribute the message. The neurotransmitters lodged in the axon of one neuron are secreted by it and taken up by a neighbouring cell - located at a distance of about 20 nanometres - which in turn secretes them for absorption by another, resulting in a perfect, uninterrupted chain of communication.
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