Reflex Arc

• Reflex arc components


  • Sensory neuron
  • Relay neuron
  • Motor neuron
• Sensory neuron


  Its function is to detect sensations, for example pain, at sensory receptors. An action potential then travels across the nerve, passing along the myelinated axon, and then the electrical signal is converted into a chemical signal to cross the synapse.
• Relay neuron


  Its function is to aid transmission, a new action potential forms in the dendrites, this neuron is in the spine and sends a signal to the CNS but also immediately sends a signal along its axon to the motor neuron.
• Motor neuron


  Its function is to detect the signal from the relay neuron by a synaptic transmission and then pass the signal along its own myelinated axon to stimulate an effector, for example a muscle group in the arm, moving it away from the source of pain.