Nervous system

• Sensory neurone - carries electrical impulses from receptor to the central nervous system
• Relay neurone - carries the electrical impulse within the central nervous system
• Motor neurone - carries electrical impulse from central nervous system to the effector
• Stimulus - Receptor - Sensory neurone - CNS - Motor neurone - Effector - Response
• Stimulus: The change in the environment
• Receptors: The cells that detect the stimulus
• Effector: Brings about the response ( muscles , glands )
• Response: Muscles respond by contracting, glands respond by producing hormones
• The nervous system allows for one part of the body to communicate with another part of the body by sending electrical impulses along neurones
• Differences between structure of sensory neurone and motor neurone:

  1. In a sensory neurone the cell body is in the middle of the neurone. In a motor neurone the cell body is at the start of the neurone
  2. Sensory neurones have a dendron, motor neurones do not
• .

  
• Neurones have a long axon

  • The longer the axon, the less synapses between neurones which speeds up the transmission of the electrical impulse because the impulse slows down at the synapse

  
• Neurones have myelin sheath to speed up the transmission of the impulse
• Neurones have dendrites which allows the neurone to connect with many others, allowing the impulse to be transmitted to many different places
• Reflex actions are a protective, automatic and rapid response to a stimulus, by electrical impulses sent to the spinal cord