nervous system

• Nervous system

  Consists of the central nervous system (brain and spinal cord) and the peripheral nervous system (nerves connecting the central nervous system to receptors and effectors)
• Central nervous system consists of

  • Brain
  • Spinal cord
• Peripheral nervous system


  • Nerves connecting the central nervous system to receptors and effectors
• Sensory neurones


  Carry information from receptors to the central nervous system
• Motor neurones


  Carry information from the central nervous system to the effectors
• Relay neurones


  Connect sensory and motor neurones in the central nervous system
• Stimulus-Response


  1. Stimulus

  2. Receptor

  3. Coordinator

  4. Effector

  5. Response
• The coordinator processes information and decides on the action/behaviour in response to the stimulus
• Reflex


  Involuntary response to a stimulus
• Reflex arc


  • Stimulus detected by receptors
  • Signal travels along sensory neurone
  • Passes from sensory to relay neurone
  • Passes from relay to motor neurone
  • Signal reaches muscle (or gland)
  • Muscle responds (or gland releases chemicals)
• Synapse


  Connections between neurones
• Transmission of signal across synapse

  1. Electrical signal can't pass across so is changed to a chemical signal- neurotransmitter

  2. Neurotransmitter diffuses across the synaptic cleft

  3. Neurotransmitter binds with receptors