Neurons7 - Neurons Hormones and the Brain The All-or-None...

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Neurons, Hormones, and the Brain The All-or-None Law Neural impulses conform to the all-or-none law , which means that a neuron either fires and generates an action potential, or it doesn’t. Neural impulses are always the same strength—weak stimuli don’t produce weak impulses. If stimulation reaches a certain threshold, or minimum level, the neuron fires and sends an impulse. If stimulation doesn’t reach that threshold, the neuron simply doesn’t fire. Stronger stimuli do not send stronger impulses, but they do send impulses at a faster rate. The Synapse The gap between two cells at a synapse is called the synaptic cleft . The signal-sending cell is called the presynaptic neuron , and the signal-receiving cell is called the postsynaptic neuron . Neurotransmitters are the chemicals that allow neurons to communicate with each other. These chemicals are kept in synaptic vesicles , which are small sacs inside the terminal buttons. When
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