There are three chemicals that regulate respiration in mammals. Carbon dioxide is the most important one, followed by oxygen. When levels of carbon dioxide in blood are high, brain receptors signal increased ventilation. Oxygen levels are another important regulator, causing a rise in cardiac output. The levels of these three chemicals in the blood are closely related to the state of the human body.
These chemicals affect the rate at which we breathe, controlling both the breathing rate and the rate. In healthy people, breathing is regulated by high concentrations of CO2 and low concentrations of O2. This is not the case in unhealthy humans. Researchers have been studying the role of chemical regulators of respiration for years. Some of the first studies were performed in 1962 by Binet & Dejours P, followed by Chernick et al., and Gautier in 2003. Other important research has been conducted in the last decade, including studies by Kiwull-Schune et al. and Nye et al.
The respiratory system regulates tissue oxygenation through the delivery of arterial blood to peripheral tissues. While the respiratory rate can vary depending on the physiologic state of the organism, the respiratory system must maintain a constant concentration of carbon dioxide and oxygen in the arterial blood and interstitial fluid. Both CO2 and O2 are essential for cellular metabolism and the acid-base status of cells.
When CO2 levels rise in the blood, the respiratory center responds to the presence of CO2 by signaling the brain to increase ventilation. The brain responds to this signal with receptors that recognize too much carbon dioxide in the blood. Because carbon dioxide is more soluble in water than oxygen, respiratory neurones change their activity in response to the presence of CO2.
Moreover, chemoreceptors also play a role in the regulation of respiration. Peripheral chemoreceptors monitor changes in arterial blood concentration. They respond to changes in blood oxygen by stimulating respiratory activity. The respiratory response to hypoxia and asphyxia depends on the amount of oxygen and carbon dioxide concentration in the blood.
Respiratory rhythms are generated in the brain’s pons and medulla oblongata. Neurons that regulate the muscles of the upper airway and diaphragm receive input from neurons that control chemoreceptors and mechanoreceptors. The interactions between these three groups of neurons produce the respiratory rhythm and determine the length of each respiratory phase.
The main function of the respiratory center is to activate the muscles of respiration. In this way, breathing occurs automatically. Typically, breathing involves two stages: inhalation and exhalation. Inhalation is characterized by a sudden ramp in motor discharge, while exhalation is silent.