refers to “the regulatory system of the body that is responsible for body functions, such as heartbeat, digestion, and breathing, [things] that are not consciously directed; it consists of the sympathetic nervous system and the parasympathetic nervous system” (Ogden & Fisher, 2015, p. 773).
Ogden, P. & Fisher, J. (2015). Sensorimotor Psychotherapy: Interventions for Trauma and Attachment. W.W. Norton & Company: New York.