Explain the mechanism of reflex action

Reflex action is a form of animal behaviour in which the stimulation of a sensory organ (receptor) results in the activity of some organ without the intervention of will.
(b) For a reflex action five things are normally
essential: '
(i) receptor,
<ii) sensory nerve fibres,
(iii) a part of the central nervous system,
(iv) motor nerve fibres and
(v) effector organ such as muscles and glands.
© The sensory nerve fibres bring sensory impulses from the receptor organ to the central nervous system.
(d) The motor nerve fibres relay the motor impulses
from the central nervous system to the effector organs.