Nervous system

• what is the CNS?

  consists of brain and spinal cord
• how does the nervous system work?

  1. receptors detect a stimulus - send electrical impulses down the neurones to the CNS (COORDINATION CENTRE)
  2. sends electrical impulses down other neurones to effectors
  3. effectors bring about a response (muscles contract, gland secretes hormone)
• what happens when you touch a candle (how the reflex arc works):

  1. stimulus (heat) is detected by a receptor(skin)
  2. EI now pass from the R along the sensory neurone to the CNS
  3. reaches the synapse n chemical is released
  4. chemical diffuses across to a relay neurone in the CNS = TRIGGERS EI
  5. EI passes across RN and reaches another synapse = chemical is released = triggers EI in MN
  6. EI passes down the MN to the effector
  7. muscle contracts and pulls hand away from heat= response