An involuntary action is one which occurs without the conscious choice of an organism. A reaction in response to a stimulus that is mediated via the reflex arc is known in physiology as a reflex, but the word reflex is also used informally for those involuntary responses that originate in the brain.
Involuntary actions are opposite of voluntary actions that occur because of choice. Involuntary actions may or may not occur with the awareness of the organism performing it.
Terminate Common involuntary humans have colds heartbeat, hiccups, digestion, coughing sneezing. Breathing can also be considered involuntary.
References
Involuntary action Wikipedia(Text) CC BY-SA