The airways are similar to a tree with a trunk (the trachea), two large main branches (the main bronchi), numerous small branches and twigs (bronchi and Bronchiolen) and - at the very end of lowest branches - many leaves, the so-called pulmonary vesicles or alveoli.

Breathing enriches the blood with oxygen from the air. It works like this: The lungs are bubbles of blood lapped. Ensure the finest blood vessels, the walls enclosing the lungs bubbles. These take oxygen from the air and then carbon dioxide (CO2) from the blood. The red blood cells to carry oxygen recorded in all regions of the body. This exchange works only in the lung bubbles. That is why it is important that the breathing air through the trachea and bronchi unhindered flow can be up there.

We breathe in every minute many times on and off. This usually happens unconsciously, without that we must be careful. It remains unconscious breathing rhythm is not always the same. For various reasons, we sometimes automatically breathe faster and shallower or slower and deeper on and off. A rapid breathing can load, for example in sport, but also in diseases of the lungs to ensure that the gas needed to be speeded up. In peace or sleep well enough on the other hand, a slow breathing rate to generate enough oxygen in and carbon dioxide.

The airways are not rigid pipes. Rather, the bronchi and Bronchiolen of fine muscle fibers surrounded the pull together and ensure that the airway can constrict. Again, this happens unconsciously. Inside are the airways with mucous membrane. This includes

• Cells that produce mucus,
• Immune cells that destroy unwanted substances or encapsulate and
• The mucus in the direction from the trachea bronchus

With its ability to constrict, mucus production and external transport, the airways have an effective defense system. Allergy triggers, dust, smoke and small foreign bodies, but also bacteria and viruses that can activate the immune system and an additional stimulus to trigger coughing.