Involuntary regulation of breathing is carried out by the respiratory center located in the medulla oblongata. From him, nerves receive impulses to the respiratory muscles. Approximately every 4 seconds, excitation occurs in the respiratory center, providing alternation of inspiration and expiration. The respiratory center not only regulates the rhythmic alternation of inspiration and expiration, but also is able to change the frequency and depth of respiratory movements, adapting breathing to the needs of the body, ensuring the optimal content of gases in the blood. The main factor regulating the respiratory rate is the concentration of carbon dioxide in the blood. When it rises, blood vessel receptors send nerve impulses to the respiratory center, from which impulses enter the diaphragm and intercostal muscles, which leads to their reduction.
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