Diagram of reflex arc with its …

In man and other vertebrate animals, there are two types of actions viz. voluntary and involuntary actions. The actions carried out and regulated by brain are voluntary actions. The actions carried out without direct concern of brain are involuntary actions. The involuntary actions are conducted by spinal cord and are known as reflex actions.
Reflex arc: For a reflex action, the path taken by a stimulus from some reception to one or more effectors is known as reflex arc. Once the sensory organ is excited by some stimuli, the message is carried by the sensory nerves to the spinal cord. From the spinal cord the directions carried by the motor nerve fibres to one or more effector organs. The whole action is completed instantaneously. Some of the examples of reflex actions are blinking of eyes, sneezing, coughing in response to foreign particle that has entered in eye, nose, the throat respectively.