A respiratory control center at the base of your brain controls your breathing. This center sends ongoing signals down your spine and to the muscles involved in breathing.
These signals ensure your breathing muscles contract (tighten) and relax regularly. This allows your breathing to happen automatically, without you being aware of it.
To a limited degree, you can change your breathing rate, such as by breathing faster or holding your breath. Your emotions also can change your breathing. For example, being scared or angry can affect your breathing pattern.
Your breathing will change depending on how active you are and the condition of the air around you. For example, you need to breathe more often when you do physical activity. In contrast, your body needs to restrict how much air you breathe if the air contains irritants or toxins.
To adjust your breathing to changing needs, your body has many sensors in your brain, blood vessels, muscles, and lungs.
Sensors in the brain and in two major blood vessels (the carotid (ka-ROT-id) artery and the aorta) detect carbon dioxide or oxygen levels in your blood and change your breathing rate as needed.
Sensors in the airways detect lung irritants. The sensors can trigger sneezing or coughing. In people who have asthma, the sensors may cause the muscles around the airways in the lungs to contract. This makes the airways smaller.
Sensors in the alveoli (air sacs) can detect fluid buildup in the lung tissues. These sensors are thought to trigger rapid, shallow breathing.
Sensors in your joints and muscles detect movement of your arms or legs. These sensors may play a role in increasing your breathing rate when you're physically active.