The document discusses the autonomic nervous system and its control of voluntary and involuntary functions in the human body. It states that voluntary functions like walking and lifting a pen are under our control and can be done at will, while involuntary functions like heart beating, respiration, and digestion are regulated unconsciously by the autonomic nervous system. These involuntary functions cannot be directly started or stopped by the ANS, but their rate can be increased or decreased, such as breathing speeding up during exercise. The autonomic nervous system is divided into the sympathetic and parasympathetic nervous systems, with the sympathetic response dominating during fighting and the parasympathetic response during rest activities like listening to music or eating.