A simple reflex arc is formed of six elements which are:- RECEPTOR ORGAN → AFFERENT NEURON (I.E. SENSORY NEURON) → SYNAPSE → ADJUSTOR NEURON (I.E. INTERMEDIATE NEURON) → SYNAPSE → EFFERENT NEURON (I.E. MOTOR NEURON) → EFFECTOR ORGAN.
The afferent neurons are sensory in nature which carries sensory impulse from receptor organ (e.g. skin) toward intermediate neuron through synapse.
The efferent neurons are motor in nature which carries motor impulses generated by intermediate neuron towards effector organ (e.g. muscles and glands).
NOTE: IN THE ABOVE REFLEX ARC PATHWAY TWO SYNAPSES ARE MENTIONED BUT ONLY ONE IS CONSIDERED.