Definition of Vital bodily function

Vital bodily function: 1. An essential bodily function. 2. A key function for life. 3. A function required by most, if not all, people.

The definition of vital bodily functions is prerequisite to the determination of death. But what are the vital bodily functions? Do they include cerebral function? Which cerebral function? Do vital functions include spontaneous function of the respiratory system? How about assisted ventilation? And is one of the vital functions the spontaneous operation of the circulatory system? If a person is on a heart-lung machine, do they still have vital bodily functions? Or are they dead?

Vital bodily functions also may include urination and defecation, as reflected, for example, by the statement in a nursing journal that: "Ostomy surgery is a life-enhancing procedure that restores a vital bodily function."