RESPONDING TO CHANGE
- Hormones, secreted by special glands, are chemicals that help control and co-ordinate processes in your body.
- The nervous system uses electrical impulses to enable you to react to your surroundings and co-ordinate what you do.
- Cells called receptors detect stimuli ( changes in the environment).
- Impulses from receptors pass along sensory neurones to the brain. Impulses are sent from the brain to the effector organs along the motor neurones.
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- Some responses to stimuli are automatic and rapid and are called reflex actions.
- Reflex actions run everyday bodily functions and help you to avoid danger.
- stimulus ---> receptor ---> co-ordinator ---> effector ---> response
- Reflex actions involve just three types of neurone. These are;
1. sensory neurones
2. motor neurones
3. relay neurones which simply connect a sensory neurone and a motor neurone. We find relay neurones in the CNS, often in the spinal chord.
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