breathing

Eva Rudolf-Müller is a freelance writer in the medical team. She studied human medicine and newspaper sciences and has repeatedly worked in both areas - as a doctor in the clinic, as a reviewer, and as a medical journalist for various specialist journals. She is currently working in online journalism, where a wide range of medicine is offered to everyone.

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In the course of breathing, oxygen is absorbed from the air in the lungs into the blood. At the same time, the blood releases carbon dioxide into the air as a metabolic waste product so that it can be exhaled with it. Here you can read everything you need to know about the respiratory system and breathing: definition, process, disorders!

What is breathing

Breathing is the vital process in which oxygen is taken from the air (external breathing) and transported to all body cells, where it is used to generate energy (internal breathing). This creates water and carbon dioxide as waste products. The latter is released into the exhaled air in the lungs and thus removed from the body. But how does human breathing work in detail?

External breathing

The so-called external breathing (lung breathing) happens in the lungs. It describes the absorption of oxygen from the air we breathe and the release of carbon dioxide into the air we breathe. The whole thing is controlled by the breathing center in the brain. In detail, external breathing works as follows:

Oxygen-rich air flows through the mouth, nose and throat into the windpipe, where it is warmed, moistened and cleaned on its way. From the trachea it continues into the bronchi and their smaller branches, the bronchioles. At the end of the bronchioles, the air you breathe reaches the approximately 300 million alveoli. These are very thin-walled and surrounded by a network of very fine blood vessels (capillaries). The gas exchange takes place here:

The oxygen in the breath diffuses through the membrane of the alveoli into the blood, where it binds to hemoglobin (red blood pigment in the red blood cells). At the same time, the carbon dioxide diffuses from the blood into the alveoli and is then exhaled with the air.

By the way: the surface of the alveoli, through which the gas exchange takes place, covers a total area of ​​50 to 100 square meters. That is about fifty times more than the surface of the body.

The hemoglobin transports the bound oxygen with the bloodstream to all organs and to all cells that need it for energy production.

Inner breathing

Internal respiration is also called tissue respiration or cell respiration. It describes the biochemical process by which organic substances are changed (oxidized) with the help of oxygen in order to release the energy stored in the substances and make it usable in the form of ATP (adenosine triphosphate). ATP is the most important form of energy storage within cells.

In the course of internal respiration, carbon dioxide is produced as a waste product. It is transported by the blood to the lungs and exhaled there (as part of external breathing).

The respiratory muscles

The body needs the breathing muscles to inhale and exhale air. When breathing at rest, which is usually chest breathing, the diaphragm is the most important muscle for breathing in. The three rib muscles that attach to the cervical vertebrae help. The intercostal muscles only serve to stabilize the chest wall during resting breathing.

When physical work makes breathing deeper or illness makes breathing difficult, inhalation increases. Then the intercostal muscles lift the ribs and expand the chest cavity (more volume!). The diaphragm, which is domed upwards in retirement, flattens out when breathing is forced, pushes the abdominal organs downwards and arches the abdominal wall outwards. This also enlarges the chest cavity. Since the lungs are firmly attached to the inside of the chest wall, they must also expand as the chest space expands. As a result, outside air is increasingly drawn in via the trachea and bronchi.

No muscle tension is necessary when exhaling - it is done passively: the diaphragm relaxes and, due to its inherent elasticity, takes on the domed shape again. This shrinks the chest and thus the lungs, so that the air inside flows out. You can also consciously exhale forcefully (forced exhalation). The abdominal muscles are used to push the abdominal viscera upwards and thus to push the diaphragm upwards.

What is the function of breathing?

The purpose of human breathing is to use the gas exchange in the lungs to obtain oxygen for energy production in the cells and to remove the waste product carbon dioxide from the organism.

Since the human body needs oxygen but cannot store it, it has to be breathed continuously. The average breathing rate at rest for adults is 12 to 16 breaths per minute; with physical exertion it can be up to 45 breaths per minute. A newborn baby breathes about 40 times per minute. During sleep, his breathing rate drops to 20 to 40 breaths per minute.

Where does breathing take place?

External breathing occurs in the lungs. The absorbed oxygen is carried into all body cells via the blood. This is where the inner breathing takes place.

What problems can breathing cause?

When someone feels that they are not getting enough air, it is called shortness of breath or dyspnea. People often try to breathe quickly, shallowly or deeply to meet their oxygen needs.

There are many possible causes of dyspnea. Sometimes it is caused by a lung disease such as asthma, COPD, pneumonia or pulmonary embolism. Heart diseases such as heart failure or heart attacks can also cause shortness of breath. In other cases, it may cause chest injuries (such as a broken rib), cystic fibrosis, allergic reactions, or respiratory infections (such as diphtheria). Finally, there is also psychogenic dyspnea: Here the shortness of breath is triggered, for example, by stress, depression or anxiety disorders.

If the oxygen level in the blood is low as a result of a disturbance in the respiratory system, this is called hypoxia. It quickly becomes life-threatening when breathing stops completely: After about four minutes without oxygen, the brain cells begin to die, which leads to brain damage and ultimately death.

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