Neurones and the nerve impulse, the action potential, synaptic transmission, and a comparison of nervous and hormonal control.
Animals coordinate responses using the fast, short-lived nervous system and the slower, longer-lasting endocrine (hormonal) system.
Neurones and the reflex arc
A neurone carries electrical impulses. Sensory neurones carry impulses from receptors to the CNS; relay neurones connect within the CNS; motor neurones carry impulses to effectors. A reflex arc (receptor → sensory → relay → motor → effector) gives a fast, automatic, protective response. The myelin sheath insulates the axon and speeds transmission (saltatory conduction — the impulse jumps between nodes of Ranvier).
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