Reflexes

• What is the primary function of reflexes?


  To help prevent injury
• How do reflexes affect the chances of being injured?


  They reduce the chances of being injured by providing quick responses to stimuli
• What happens when you touch a hot pan?

  A reflex reaction causes you to immediately move your hand away
• What is the reflex arc and its pathway?


  • Stimulus detected by receptors
  • Impulses sent along sensory neurones to the CNS
  • Chemicals released at synapses between sensory and relay neurones
  • Impulses sent along relay neurones
  • Chemicals released at synapses between relay and motor neurones
  • Impulses sent along motor neurones to the effector
  • Effector (muscle) contracts and produces a response
• What is the role of the central nervous system in reflex actions?

  The CNS processes the impulses from sensory neurones
• What occurs at the synapse between the sensory neurone and the relay neurone?


  Chemicals are released that trigger impulses in the relay neurone
• Why are reflex actions quicker than normal responses?


  Because they bypass the conscious brain, allowing for immediate reactions
• What is an example of a stimulus that can trigger a reflex action?


  A bee sting
• What is the effector in the reflex reaction of moving your hand away from a hot pan?


  The muscle that contracts to move your hand
• What is the first step in the reflex action pathway?


  Detection of a stimulus by receptors
• What happens when impulses reach the muscle in a reflex action?


  The muscle contracts
• If a chef touches a hot pan, what is the immediate reflex action?


  He moves his hand away
• What is the role of adrenaline in reflex actions?


  It helps prepare the body for a quick response
• Why do reflexes bypass the conscious brain?


  To allow for quicker responses when immediate action is essential