Inspiration: Function, Tasks, Role & Diseases

Inspiration (inhalation) is a phase of the respiratory cycle. During inspiration, fresh and oxygen-rich air enters the lungs, from where it supplies the entire body with vital oxygen.

What is inspiration?

Inspiration, in German inhalation, is a part of the breathing cycle. During inspiration, fresh and oxygen-rich breathable air enters the alveoli of the lungs, causing the lungs to expand. In contrast to the more passive exhalation, inspiration is an active process, as the respiratory muscles must tense to do the necessary pressure-volume work. A distinction is made between thoracic and abdominal breathing during inspiration.

Function and task

Inspiration (inhalation) is a phase of the respiratory cycle. During inspiration, fresh and oxygen-rich air enters the lungs, from where it supplies the entire body with vital oxygen. Inspiration provides the body with fresh, oxygen-rich air. At the same time, the condition is created for the carbon dioxide produced by the body to be exhaled. In order for the fresh air to breathe in, the respiratory muscles and the auxiliary respiratory muscles must work. As a result, the chest expands, which is visually visible by a lifting of the same. The lungs follow the movements of the rib cage due to the pleura, a layer of tissue consisting of two sheets between the lungs and the rib cage, which adhere strongly to each other due to a fluid between them. Since the lung is very elastic, it expands along with the rib cage, creating a negative pressure in the lung. This allows the inhaled air to flow in through the airways. The muscles that mainly work during the inspiration phase depend on the type of breathing. In thoracic breathing, the intercostal muscles and the respiratory accessory muscles are primarily active, causing the chest to expand and make room for the lungs. In abdominal breathing, on the other hand, the diaphragm does much of the work of breathing. Its contraction allows the lungs to expand downward. Before the breath reaches the lungs, it passes through the nose or mouth, throat, larynx, trachea, and bronchi. Once the breathing air has reached the lungs, gas exchange takes place in the approximately 300,000 alveoli, or air sacs. This means that oxygen from the inhaled air passes from the alveoli into the blood by diffusion and, at the same time, carbon dioxide passes from the blood into the alveoli. This allows the carbon dioxide to be removed from the body during expiration, the second major phase of the respiratory cycle. The oxygen-rich blood supplies all the cells of the body with vital oxygen via the human circulatory system. Only with sufficient oxygen can the respective cells continue their metabolic processes. However, not all of the oxygen inhaled is used by the body; a large proportion is exhaled again. While the inhaled air is enriched with 21 percent oxygen, the exhaled air still contains around 17 percent oxygen. For this reason, inspiration is also possible in the case of respiratory arrest, because the exhaled air still contains sufficient oxygen. The entire process of inspiration is automatically controlled by the respiratory center in the medulla oblongata. However, a perfected breathing technique with conscious inhalation is also possible and leads to better body awareness, which can be important, for example, when playing music or certain sports.

Diseases and ailments

When inhaling, numerous problems can occur. Even if they are temporary, complaints during inspiration should always be taken seriously. In some cases, the corresponding complaints are psychological. Some disorders during inspiration and their consequences can cause significant and far-reaching health problems for the affected person. The most serious case is acute respiratory arrest, which is fatal after only a few minutes due to the lack of oxygen supply to the cells. Disturbances during inhalation are usually noticeable through pain, sounds, a change in breathing rate or the subjective feeling of shortness of breath. Accidentally inhaled foreign bodies may also interfere with inspiration. The causes of complaints during inspiration can be as varied as their appearance and can be located both in the area of the chest and outside.Often, the cause of the inhalation problems already lies in the upper or lower airways. If these are blocked, this manifests itself as a soft whistling noise and difficult inhalation. Damaged bronchi, for example due to bronchitis or asthma, and lung damage, for example as a result of pneumonia, can also lead to considerable shortness of breath. The lungs and the heart are closely connected. Therefore, heart conditions can also lead to problems with inspiration. General, chronic heart failure or even an acute heart attack can lead to pulmonary edema. In this case, fluid can accumulate both in the lungs themselves, which is often manifested by a bubbling sound when breathing in, and in the pleura, between the lungs and the pleura. All of these conditions can lead to a significant lack of oxygen and associated shortness of breath. If air is present in the pleural space between the lungs and the rib cage, there is a risk of complete lung collapse. This, like pulmonary embolism caused by occlusion of the pulmonary vessels, is very dangerous because of the rapid onset of significant oxygen deprivation.