The nervous system

• the nervous system is made of neurones which go to all parts of the body
• the body has lots of sensory receptors - a group of cells that can detect a change in the environment (stimulus). different receptors detect different stimuli
• when a stimulus is detected by receptors, the information is converted into a nervous electrical impulse
• the nervous impulse is sent along sensory neurones to the CNS (brain and spinal cord)
• the impulses travel through the CNS along relay neurones
• the CNS sends impulses along a motor neurone to an effector ( muscle or gland)
• the effector then responds e.g. a muscle contracts
• neurones transmit information rapidly as electrical impulses
• neurones have : cell body, dendrites/dendrons and an axon
• dendrites/dendrons : extensions that carry nervous impulses towards the cell body
• axons - extensions that carry nervous impulses away from the body
• myelin sheath - fatty material which speeds up electrical impulses
• sensory neurone - carries impulses from the receptors to the CNS
• relay neurone : carries impulses through the CNS
• motor neurone - carries impulses from the CNS to effectors