Bodily functions that follow "a law unto itself" are controlled by the involuntary nervous system. this system is also termed and functions to

Involuntary nervous system also known as autonomous nervous system.It is a division of pheripheral nervous system that supplies smooth muscle and glands,and influence the function of internal organs. It functions largely unconsiously and regulates bodily functions such as heart rate ,digestion,respiratory rate,pupillary response,urination.,and sexual arousal.