Alveoli are important components of the lungs. They are responsible for the exchange of gases between blood and the outside world. The alveoli provide for the intake of fresh air and for the removal of the resulting by breathing carbon dioxide. If alveoli are damaged, the breathing is severely restricted. Curative treatment options for damage to the alveoli are not currently available; With appropriate therapies, a certain level of quality of life can be maintained.

What are alveoli?

Schematic representation of the anatomy and structure of the lung and bronchi. Click to enlarge.

The alveoli are central to the lungs. They are at the end of the bronchi or bronchioles. They are responsible for a smooth gas exchange between body and environment. Humans have about 300 million alveoli.

Alveolar lobes are well protected by the bronchi lying in front of them, so that they are usually not affected even in severe infections. However, if the alveoli are massively damaged or killed due to heavy pollution, respiratory function can not be maintained.

Once destroyed, alveoli do not grow or their function can be taken over by other vesicles. Diseases that are due to the destruction of the alveoli can therefore not be treated curatively.

Anatomy & Construction

The structure of the lung is like a tree. The trachea (the trunk) opens into the lungs. There, the tube branches in countless branches, the bronchi. The bronchi, on the other hand, have very fine branches, the bronchioles. On the bronchioles are small leaflets, the alveoli.

In the alveoli gas exchange takes place. In both lungs there are a total of about 300 million vesicles. Each lung has a diameter of about 0.2 millimeters. Spread out this results in a total surface of almost 100 square meters. For comparison, the skin has about an area of ​​2 square meters. The alveoli are surrounded by a network of hair-thin blood vessels. Between the blood vessel and the alveoli there is a permeable skin layer, with the help of which gas exchange takes place.

The skin layer is permeable in both directions, so that on the one hand fresh air can be delivered from the alveoli into the blood vessel. On the other hand, the alveoli absorbs used air and releases it to the outside. Alveoli are hollow inside. In the cavities they can store the fresh air and the exhaust air for a short period of time. Individual alveoli are separated by a membrane.

Function & Tasks

The central task of the alveoli is to ensure the exchange of gas between the body and the environment during respiration. During breathing, the lungs initially absorb fresh air from the environment.

The air is transported via the trachea, bronchi and bronchial tubes to the alveoli. There, the air sac stores the respiratory air in a cavity and then releases it via a thin layer of skin into the blood vessel that spans it.

The other way around, the gas exchange works similarly: The blood vessel transports the used exhaust air to the alveoli. There, the harmful carbon dioxide from the blood diffuses into the cavity of the pulmonary alveolus. It is briefly stored there and ejected into the environment on the next breath.

Diseases & complaints

Alveoli generally do not cause discomfort. Even with a severe cold, bronchitis or asthma, the alveoli are well protected by the bronchi and bronchial tubes. Only with chronic damage to the bronchi can the alveoli be damaged; normal breathing is then no longer possible.

Breathing causes numerous pollutants to enter the lungs. Under normal conditions, the lungs can carry the pollutants away with the help of the bronchi and the alveoli. However, if the strain is permanently too high, the mucous membranes of the bronchi initially swell. To be able to transport the mucus, man coughs and repels the mucus (ejection).

If the load persists, mucus production and consequent narrowing of the respiratory tracts progresses and can not be reversed, even if there is no pollution. In the course of the COPD disease (COPD = chronic obstructive pulmonary disease) the alveoli are damaged. The damage manifests itself in a complete destruction of the pulmonary alveolar skin. The result is so-called emphysema bunches. The emphysema sacs inflate and take up considerable space in the lungs without fulfilling any purpose.

The lung capacity decreases, the patient is increasingly suffering from shortness of breath. In the worst case, the patient can no longer participate in everyday life due to the shortness of breath, but is relatively unable to move. The most common cause of COPD is heavy smoking. Sooner or later, smokers will almost certainly fall prey to COPD.

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