together, these blood oxygen monitors contribute nerve signals to the vasomotor center of the medulla which can modulate several processes, including breathing, airway resistance, blood pressure, and arousal, with central chemoformation about medullary oxygen levels and peripheral chemoreceptors about arterial oxygen. at an evolutionary level, this stabilization of oxygen levels, which also results in a more constant carbon dioxide concentration and ph, was important to manage oxygen flow in air-vs.-water breathing, sleep, and to maintain an ideal ph for protein structure, since fluctuations in ph can denature a cell's enzymes.