B3.1 the nervous system

• in vertebrates (animals with a backbone)

  the CNS allows information to be processed and acted on
• CNS consists of the brain and the spinal cord
• the spinal cord and body organs are connected by the nerves
• the network of nerves that connect the CNS to the body organs is called the peripheral nervous system
• the peripheral nervous system:

  • sensory neurone
  • relay neurone
  • motor neurone
• sensory neurones transmit signals from receptors
• relay neurones transmit signals between neurones
• motor neurones transmit signals to effectors
• an automatic response is called a reflex
• VOLUNTARY RESPONSE

  1. receptor
  2. sensory neurone
  3. brain (to process info)
  4. motor neurone
  5. effector
  6. response
• INVOLUNTARY RESPONSE

  1. receptor
  2. sensory neurone
  3. relay neurone
  4. motor neurone
  5. effector, response
• reflex actions are faster as the brain is skipped
• neurones are long so signals can be sent long distances
• 1. dendrites
  2. cell body
  3. nucleus
  4. dendron/axon
  5. myelin sheath

  
• receptor cells detect change in environment
• effectors are the part of the body that carry out the response
• the reflex arc

  reflexes enable a quicker response to reduce the time the body is at risk