Question

If breathing is a part of respiration, then shouldn't even respiration be voluntary?

Answer 1

Breathing is special in several respects: it is the only function you can perform consciously as well as unconsciously, and it can be a completely voluntaryact or a completely involuntaryact, as it is controlled by two sets of nerves, one belonging to the voluntary nervous system, the other to the involuntary. But respiration is usually referred to as a chemical reaction where oxygen is used to breakdown glucose in order to generate energy which is then used by the cell to function. This function can't be voluntary.