Reflexes

• what are reflexes?


  rapid, automatic responses to stimuli
• What is a reflex?


  where the body responds to a stimulus without making a conscious decision to respond
• why does info travel really fast from receptors to effectors?


  Because you do NOT have to spend time deciding how to respond
• why do simple reflexes help organisms to protect the body?

  they are rapid
• What is a reflex arc?

  the pathway of neurones linking receptors to effectors in a reflex
• Give example of a simple REFLEX ARC- the hand-withdrawal response to heat?

  1. thermoreceptors in skin detect heat stimulus
  2. sensory neurone carries impulses to relay neurone
  3. Relay neurone connects to the motor neurone
  4. motor neurone sends impulses to effector (biceps muscle)
  5. muscle contracts to withdraw hand & stop it being damaged
• What is possible if there is a relay neurone involved in the simple reflex?

  It is possible to override the reflex eg brain could tell hand to withstand the heat