hengitysärsykettä

Hengitysärsyke, often translated as respiratory stimulus, refers to the physiological mechanisms that trigger and regulate breathing. The primary driver of respiration is the need to maintain appropriate levels of carbon dioxide and oxygen in the blood. The body constantly monitors these gases, primarily through chemoreceptors located in the brainstem and major arteries.

The most significant respiratory stimulus is the level of carbon dioxide (CO2) in the blood. An increase in CO2, which is a byproduct of cellular metabolism, is detected by the central chemoreceptors in the medulla oblongata. This detection leads to an increased rate and depth of breathing, a process known as hyperventilation, to expel excess CO2. Conversely, a decrease in CO2 levels will suppress the respiratory drive.

Oxygen levels also play a role, though usually to a lesser extent under normal circumstances. Peripheral chemoreceptors in the carotid and aortic bodies are sensitive to low oxygen (hypoxia) and high carbon dioxide levels. When oxygen levels drop significantly, these receptors send signals to the brainstem to increase breathing. However, the body's response to low oxygen is generally less sensitive than its response to elevated carbon dioxide.

Other factors can influence the respiratory stimulus, including changes in pH, stretch receptors in the lungs that prevent overinflation (Hering-Breuer reflex), and voluntary control from the cerebral cortex. Emotional states, pain, and exercise can also modify breathing patterns by acting on the respiratory centers. Understanding these stimuli is crucial for comprehending respiratory physiology and diagnosing respiratory disorders.