As a respiratory expert with a background in both medicine and physiology, I'm delighted to delve into the intricate process of how breathing is controlled. The respiratory system is a complex and fascinating network that ensures the efficient exchange of oxygen and carbon dioxide, which is vital for life. Let's explore this in detail.
Breathing Control Center
The control of breathing is primarily managed by a group of neurons known as the respiratory control center. This center is located in the medulla oblongata, which is a part of the brainstem situated at the base of the brain. The medulla is responsible for many vital functions, including the control of heart rate, blood pressure, and, most importantly for our discussion, respiration.
Neural Pathways and Signals
The respiratory control center sends out signals through the phrenic nerve to the diaphragm, a dome-shaped muscle that separates the chest cavity from the abdominal cavity. It also sends signals through other nerves to the intercostal muscles, which are the muscles between the ribs. These signals are rhythmic and ensure that the breathing muscles contract and relax in a coordinated manner.
Influence of Carbon Dioxide
One of the most significant factors that influence the respiratory control center is the level of carbon dioxide (CO2) in the blood. When CO2 levels rise, it leads to a decrease in blood pH, a condition known as respiratory acidosis. The medulla is highly sensitive to changes in blood pH and responds by increasing the rate and depth of breathing to expel excess CO2 and restore pH balance.
Influence of Oxygen Levels
While CO2 is the primary driver of the respiratory control system, oxygen (O2) levels also play a role. Oxygen sensors in the carotid bodies and the aortic bodies detect changes in blood oxygen levels. If oxygen levels drop, these sensors send signals to the respiratory control center to increase the rate and depth of breathing to take in more oxygen.
Chemoreceptors and Reflexes
In addition to the chemoreceptors in the carotid and aortic bodies, there are also central chemoreceptors located in the medulla itself. These receptors are sensitive to changes in the pH, CO2, and O2 levels in the blood. They work in conjunction with the respiratory control center to regulate breathing through a series of reflexes, such as the Herning-Breuer reflex and the diving reflex.
Hering-Breuer Reflex
The Hering-Breuer reflex is an inhibitory reflex that helps to prevent over-inflation of the lungs. When the lungs are inflated to a certain point, the reflex is triggered, causing the diaphragm and intercostal muscles to relax, thus ending the inhalation phase of breathing.
Diving Reflex
The diving reflex is a protective mechanism that occurs when the face is submerged in cold water. It involves a temporary slowing of the heart rate and a decrease in breathing rate to conserve oxygen for when it is most needed, such as during a dive.
Voluntary Control
While the respiratory control center operates largely involuntarily, there is a degree of voluntary control over breathing. This is particularly evident when we engage in activities like singing, playing a wind instrument, or practicing yoga, where we consciously control the rate and depth of our breaths.
Circadian Rhythms and Sleep
Breathing patterns also change with the circadian rhythms and during sleep. During rapid eye movement (REM) sleep, the respiratory rate can become irregular, and the response to CO2 can be diminished. However, the respiratory control center continues to function, ensuring that breathing remains within a safe range.
Conclusion
In summary, breathing is a complex physiological process that is primarily controlled by the respiratory control center in the medulla oblongata. It is influenced by various factors, including CO2 levels, O2 levels, and the body's internal and external chemoreceptors. The system is designed to be responsive to the body's needs, ensuring that we maintain a balance of gases that is essential for life. The ability to voluntarily control our breath also allows us to adapt to various activities and situations.
read more >>

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.May 22, 2017read more >>