Respiration in humans is controlled by medulla, which is a part of the brain. The medulla is responsible for the provision of adequate amount of oxygen for every activity. Medulla sends signals to our body to provide oxygen for every activity like sleeping, eating, walking, exercising etc. Human brain measures the level of carbon dioxide in blood and makes necessary adjustments to balance the amount of oxygen and controls respiration rate. Breathing is controlled by the brain but it can be controlled voluntarily also like holding ones breath. But this is just temporary and the medulla takes charge again after a few minutes to restore the breathing.