Air inflow into the lungs and air outflow from the lungs are grouped under the term ventilation or aeration. Ventilation is used for gas exchange in the lungs, and the alveoli release molecular oxygen into the blood and mainly absorb carbon dioxide from the blood. The absorbed gaseous carbon dioxide is exhaled from the lungs with the airflow and released into the environment.
What is ventilation?
Airflow into the lungs and airflow out of the lungs are collectively referred to as ventilation or aeration. Ventilation is the term used to summarize the inflow of air into the lungs and the outflow of air from the lungs. The necessary gas exchange takes place in the alveoli, the air sacs in the lungs. Some of the molecular oxygen inhaled is taken up and dissolved by the carbon dioxide-rich blood in the capillaries surrounding the alveoli, while some of the carbon dioxide dissolved in the blood diffuses into the alveoli and is released into the environment with exhalation. The alveoli exchange the carbon dioxide, which is already used by the cells for energy, for oxygen. The carbon dioxide is produced during the cells’ energy production process. In a multistage combustion process of carbohydrates, catalytically controlled by enzymes (cellular respiration), the main waste products are water and carbon dioxide. The part of the airflow that enters the alveoli directly is called alveolar ventilation. The portion of inspired air that does not participate directly in gas exchange because it fills supporting organs such as the trachea and bronchi is called dead space ventilation. Dead space ventilation accounts for just under one-third of the total volume of air inhaled in a normal breath (breath volume).
Function and task
The main function of ventilation is to provide molecular oxygen for cellular respiration and to carry carbon dioxide left over from cellular respiration out of the body. Ventilation thus has a clear support function for cellular respiration. This applies not only to alveolar ventilation, but also to dead space ventilation. Anatomically, the dead space includes not only the bronchi and trachea, but also the nasal and pharyngeal cavities. As part of ventilation, the dead space performs important functions such as filtering out solid particles (dust) and, to some extent, pathogenic germs in the nose. The air intended for gas exchange is previously warmed to body temperature or cooled, depending on the ambient temperature, and the inhaled air is saturated with water vapor so that 100% relative humidity is achieved. The air entering the alveoli is already optimally conditioned so that the best possible gas exchange can take place. Another task of ventilation is to aerate the entire respiratory system. During low physical activity or when bedridden, there is little demand on ventilation, so that affected persons usually breathe very shallowly, and when lying on their side in conjunction with shallow breathing, not all corners of the lungs and dead space are ventilated. This favors bacterial accumulation and growth, so that ventilation can no longer fully perform its scavenging function. Thus, the protective function of ventilation is limited. Targeted respiratory gymnastics can provide relief in such cases. If the patient is confined to bed, it is advisable to change position from time to time in order to repeatedly ventilate other areas of the lungs. Involuntary ventilation is mainly controlled by the respiratory center in the [[medulla oblongata[[. The medulla oblongata is located between the midbrain (mesencephalon) and the spinal cord. In addition to the respiratory center, other control centers are located there. In addition to being controlled by the respiratory center, ventilation can also be controlled consciously, by respiratory rate and respiratory volume.
Diseases and ailments
Functioning ventilation is essential for human survival. Suspension of breathing leads to serious problems due to lack of oxygen supply (hypoxia) after only a few minutes. There are many known organic diseases that make breathing difficult even though the neural control center is completely intact. A common cause of breathing difficulties is bronchial asthma, which is triggered by an overreaction of the immune system to certain substances and, in extreme cases, can lead to spasms and choking.Acute heart disease associated with heart failure can also cause pulmonary edema with water retention in the lungs, which can lead to impaired ventilation and even respiratory distress. In chronic bronchitis or pneumonia, there are breathing difficulties caused by the diseased respiratory organs themselves. If blood clots (thrombi) have formed somewhere in the body and can be carried further with the bloodstream, a pulmonary embolism can occur as soon as the thrombus becomes lodged in an artery supplying the lungs and blocks it. If it is an occlusion of an artery supplying a large portion of the lung, the embolism can quickly become life-threatening. Altered and abnormal ventilation can also be caused by diseases of other organs. In the case of pathological anemia, oxygen transport is impaired, which can cause symptoms of shortness of breath due to severe carbon dioxide concentration. Similar symptoms can occur in the case of severe hyperglycemia due to type I diabetes. Typically, this leads to deepened breathing without pause because of the acidity of the blood, which is also known as kissing-mouth breathing. Strokes or brain inflammation (encephalitis) or nervous system disorders caused by medications, neurotoxins, or often by intense psychological pressure can cause noticeable breathing patterns, including gasping. Gasping is often a warning signal and may herald impending respiratory failure.
