The body must responnd to internal and external conditions: you have glands that produce hormones, these are transported round your body by the blood; electrical impulses pass along the nervous system; all responses must be co-ordinated.
Reflex Actions
The steps involved in a reflex action:
- a receptor detects a stimulus (e.g sharp pain)
- a sensory neurone transmits the impulse
- a relay neurone passes the impulse on
- a motor neurone is stimulated
- the impulse is sent to the effector (muscle or gland)
- action is taken
At the junction between two neurones is a synapse. Chemicals transmit the impulse across the gap.
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