The answer is chemoreceptor reflexes. To simplify, Vasomotion because of changes in pH or CO2 levels would be a result of chemoreceptor reflexes. The chemoreceptors of the cardiovascular system are situated in two places in which the carotid bodies are located in the carotid arteries that run over the neck to the brain and the aortic bodies are established in the aortic arch, an arterial feature near the heart. In addition, the chemoreceptor reflexes control respiration, cardiac output, and regional blood flow, guaranteeing that appropriate amounts of oxygen are transported to the brain and heart.