A reflex action occurs when the body responds to a stimulus without the involvement of the brain. Batting of eyelids and rapid withdrawal of hands from a hot surface are examples of reflex actions. The contraction of the pupils of the eyes when exposed to bright light is a perfect example of a reflex action.
Normally, the brain coordinates a response to any stimulus via the spinal cord and the central nervous system. In certain circumstances, the brain is bypassed for a very quick response. A response takes longer when the brain, the nerves and the spinal cord are involved.
All reflex actions occur very quickly without any thinking. The action is not premeditated, and this makes it instantaneous. The pathways that cause a reflex action are called reflex arcs. These arcs consist of a sensory nerve, neurons or nerve cells and a motor nerve. Neurons are like sensory pathways. Millions of neurons are interconnected to make a nerve. Neural pathways make it possible for a reflect action to take place. Various muscle groups are involved in a reflex action.
The first reflex actions start in the womb even before birth. Reflexes related to touching, sucking and swallowing are ready by the time birth takes place.