It means that you do not have conscious control over it. Involuntary systems include ones such as digestion and circulation. You cannot tell your body when or how fast to digest your food, and it isn't possible to consciously tell your heart how fast to beat.
involuntary
The endocrine system is involuntary. A person cannot control the endocrine system by will.
Subdivision of the peripheral nervous system that regulates involuntary functions.
Involuntary actions of the body are controlled by the autonomic nervous system.
Of course! Involuntary when you don't have a mental illness.
nervous system
Involuntary, as we are not conscious of pushing food through the digestive system.
Nerves
voluntary
The man had involuntary tremors in his hands. Police can make an involuntary commitment to a hospital if a person seems to be a danger to themselves or others. A twitch is an involuntary motor reaction of the nervous system.
smooth muscles
The Autonomic Nervous System.