Reflex Actions

• Voluntary response

  Actions or reactions that are consciously controlled and initiated by the individual (involving deliberate decision-making)
• Involuntary response

  Automatic actions or reactions that do not involve conscious control (you don’t think about it)
• Reflexes

  • Involuntary, rapid responses to stimuli (you don’t need to think about it)
  • Happen almost instantaneously
  • They are responses that try to reduce chances of injury or harm/reduce damage
  • E.g. touching a hot plate 
  • Usually happens before you process what’s happening. This is because the response is made without conscious thought (acting before nerve impulses reach the brain)
• Reflex arcs

  • The pathway of information in a reflex (from receptor to effector) is called a reflex arc
  • Neurons in reflex arcs go through the spinal cord or through an unconscious part of the brain
  • Muscles are moving at the same time as the brain gets the message, making reflexes fasting that other responses
• Pathway of impulses in Reflex Arcs

  1. A receptor detects a stimulus and sends an impulse to a nearby sensory neuron
  2. Sensory neurons pass the impulse to interneurons (in the spinal cord)
  3. Interneurons send two messages at the same time – one to the brain and the other to the effectors (usually muscles) via motor neurons