What is the role of carbon dioxide in regulating breathing during exercise?

During exercise, increased carbon dioxide levels in the blood stimulate faster and deeper breathing.

When you exercise, your muscles produce more carbon dioxide as a by-product of cellular respiration. This increase in carbon dioxide concentration in the blood is detected by chemoreceptors located in the aortic and carotid bodies, as well as the medulla oblongata in the brain. These chemoreceptors are sensitive to changes in the pH level of the blood, which decreases (becomes more acidic) as carbon dioxide levels rise.

In response to this change, the chemoreceptors send signals to the respiratory centre in the brain, which in turn increases the rate and depth of breathing. This is known as the chemoreceptor reflex. The increased breathing rate (tachypnea) and depth (hyperpnea) help to expel the excess carbon dioxide from the body, bringing the blood pH back to its normal level and ensuring the body's internal environment remains stable.

This process is a key part of the body's homeostatic control mechanisms. It's important to note that while oxygen levels in the blood also play a role in regulating breathing, it's the carbon dioxide levels that primarily drive this response during exercise. This is because the body is more sensitive to changes in carbon dioxide levels than to changes in oxygen levels.

In summary, the role of carbon dioxide in regulating breathing during exercise is to ensure that the body maintains a stable internal environment. It does this by stimulating the chemoreceptor reflex, which increases the rate and depth of breathing to expel excess carbon dioxide and return the blood pH to its normal level.