Voluntary muscle contractions are initiated in the brain, while involuntary reflexes are initiated in the spinal cord.
When an action is produced with the involvement of thoughts, they are called voluntary action. It involves actions like walking, eating, jumping and running. These actions are produced consciously. Both spinal cord and brain are involved and these coordinate with PNS to generate necessary movements.
Involuntary behaviour refers to actions that occur without the individual’s knowledge or consent. Involuntary activities include digestion, heartbeat, sneezing, and others.
The same parts of the brain regulate both involuntary and voluntary acts. Salivation, vomiting, and other involuntary acts are regulated by the hindbrain and midbrain.