Nasal and mouth breathing

Nasal and mouth breathing both serve the purpose of breathing, but differ in their physiological process. Nasal breathing involves breathing in and out through the nose. With mouth breathing, on the other hand, the air is passed through the oral cavity into the other airways.

What is nose and mouth breathing?

Nasal breathing is physiological breathing. This means that a healthy person breathes in and out through the nose when at rest. If there is an increased need for oxygen and thus also breathing air, e.g. During physical activity, mouth breathing can also be physiological. Causes of permanent and thus pathological mouth breathing include polyps, colds, misaligned teeth and jaws, allergies or incorrect tongue position.

When breathing through the nose, air is drawn in through the nostrils and passed into the nasal passages. It slides along the turbinates and then passes through the throat into the windpipe, the bronchi and finally into the lungs. The gas exchange takes place there. The exhaled air mixed with carbon dioxide reaches the nasal passages via the bronchi and trachea, through the throat, and is then exhaled through the nostrils. Nasal breathing is usually done with your mouth closed.

When the body is at rest, breathing does not take place through both nostrils at the same time. The nostrils are alternately flowed through with more or less air. so that the nostril with the reduced air flow has time to regenerate the mucous membrane. This process is also known as the nasal cycle.

When breathing through the mouth, the air is drawn in through the mouth. The air is thus directly in the oral cavity, the way via the nasal passages and turbinates is completely left out. The rest of the path taken by the air to breathe corresponds to the path taken by nasal breathing. From the oral cavity, air enters the lungs through the throat and lower airways.

Function & task

The physiological form of breathing in humans is nasal breathing. There are several reasons for this. The nasal cavities and the turbinates are lined with nasal mucosa. The nasal mucous membrane is pervaded by many vessels and covered with a layer of cilia. The cilia beat in the direction of the throat about 500 times per minute. Inhaled foreign bodies and pathogens stick to the mucous membrane and are then transported by the cilia in the direction of the throat. There they are swallowed with the saliva and made harmless by the stomach acid. This prevents the foreign matter from getting into the lungs and, in the worst case, causing an infection.

Due to the many vessels, the mucous membrane is very well supplied with blood and therefore warm. Cold air flowing in through the nose is warmed by the mucous membrane. This protects the lungs and bronchi from excessively cold air. In addition, the mucous membranes ensure that the air you breathe is humidified with every breath. When breathing through the nose, the olfactory nerve is also stimulated. So-called olfactory cells are embedded in the mucous membrane. When inhaling through the nose, odor molecules reach the mucous membrane and thus enable the perception of a wide variety of smells.

Another advantage of nasal breathing is that the nitric oxide produced in the paranasal sinuses enters the lungs together with the air you breathe. Nitric oxide can destroy viruses, parasites and degenerate cells in the airways and lungs. In addition, it apparently plays a role in pain perception, sleeping and learning. Nitric oxide also ensures that more oxygen is released from the hemoglobin in the lungs. The same applies to carbon dioxide. A high carbon dioxide content promotes the absorption of oxygen in the lungs. This is known as the Bohr effect.

The nasal cavity and the paranasal sinuses belong to the so-called dead breathing space. More and more carbon dioxide collects here. When inhaled through the nose, this is transported into the lungs. Since the air bypasses the nasal cavities when breathing through the mouth, less carbon dioxide gets into the lungs and the absorption of oxygen in the lungs is made more difficult. Nasal breathing leads to a 10-15% higher oxygen saturation of the blood compared to mouth breathing.

In addition, nasal breathing seems to increasingly activate the parasympathetic nervous system. The parasympathetic nervous system is part of the autonomic nervous system. Most internal organs are controlled by him. It dampens the heartbeat and is responsible for rest and sleep. It is therefore also called the resting nerve. The antagonist of the parasympathetic is the sympathetic, the fighting and flight nerves. It activates the body and stimulates the cardiovascular system. Studies have shown that the sympathetic nervous system is significantly more active when breathing through the mouth.

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Illnesses & ailments

Obstructed nasal breathing can have various causes. In adults, the inferior turbinate is enlarged in many cases. A crooked nasal septum can also impede nasal breathing. Polyps, tumors or injuries are less common reasons.

If children can no longer breathe properly through their noses, they should always think of a foreign body. Certain medications, such as some antidepressants, hypertensives, and contraceptives, can also cause nasal obstruction. The same applies to the long-term use of decongestant nasal drops or nasal sprays. The drops cause the nasal mucous membrane to swell initially, but as soon as the effect wears off, the vessels reactively fill the vessels more intensely and thus swell even more than before ingestion.

The most common reason for obstructed nasal breathing is rhinitis, i.e. a common cold. This can be bacterial, viral or allergic.Acute or chronic inflammation of the sinuses can also make nasal breathing so difficult that additional mouth breathing is required.

Predominant mouth breathing can lead to aerophagia. Aerophagia is an excess of air in the stomach and intestines. The result is flatulence, abdominal pain and increased belching.