The human nose is not only an important aesthetic component of the face. It simultaneously houses one of our developmentally oldest senses. It also serves vital breathing and acts as an “outpost” of the body’s defense against infection.
What is the nose?
Schematic diagram showing the anatomy of the nose and sinuses. Click to enlarge. As in all vertebrates, so in humans the nose is characterized by the presence of the nostrils and the nasal cavity. It is located in the center of the human face and thus influences facial aesthetics in a significant way. Even more important than its visual function, however, is its role as the “entrance and exit” for the respiratory flow. In order for this to enter and leave the body, the nasal cavity is connected to the trachea via the pharyngeal cavity. Not visible from the outside, there are also body cells in the nose for exercising the sense of smell. This has an effect on human behavior both in combination with the sense of taste and in evaluating pheromonal fellow human messages.
Anatomy and structure
Externally, the nose can be divided from top to bottom into the root of the nose, the bridge of the nose, the two lateral nostrils, and finally the tip of the nose. The wings of the nose enclose the nostrils, which lead into the interior of the nose. The front part of the nostrils is called the nasal vestibule and is lined with hairy outer skin. The adjoining nasal cavity is divided into two parts by the so-called nasal septum. Both are lined with a mucous membrane and a ciliated epithelium with tiny cilia. The right and left nasal cavities are structured by partially bony turbinates. In the upper part of the nasal cavities are special sensory fields called olfactory bulbs. They contain a large number of olfactory cells that react with scents from the air we breathe. The resulting stimuli are transmitted to the brain via nerve fibers of the olfactory pathway. The paranasal sinuses also extend from the nasal cavities. These are air-filled outpouchings of the nasal mucosa that are thought to reduce the weight of the skull.
Functions and tasks
The most important function of the nose is to represent the opening through which breathing air can enter the body and stale air can leave. Although this is generally also possible through the mouth, it is only possible when it is open. The mouth as the sole respiratory organ would therefore not allow breathing while eating or drinking. The air breathed in through the nose is first warmed and moistened. On the one hand, this benefits the lungs, which are in danger of cramping if the air is very cold. On the other hand, this pre-treatment supports an evaluation of the scent molecules contained in the air. The air breathed is additionally purified by the nasal hairs and the cilia of the nasal mucosa retaining foreign particles. If the nasal hairs become too dirty, the sneezing reflex is also triggered to clear the nose of foreign particles. If the inhaled, warmed air then reaches the upper part of the nasal cavity, the nose can perform its function as a sensory organ. When eating, the olfactory perception is combined with the taste perception of the mouth and thus provides a complete representation of the properties of ingested food. In parallel, pheromones, i.e. sexual messengers of other people, are also perceived from the air we breathe. Although reactions to these are not as obvious in humans as in animals, instinctive likes and dislikes of fellow humans, for example, are thought to be at least partially attributable to pheromonal effects.
Illnesses
The best-known complaint of the nose is the common cold, medically rhinitis, which is an acute or chronic inflammation of the nasal mucosa. It reacts to this by swelling, which can severely obstruct nasal breathing. Often, the production of thin to viscous nasal secretions is added. Itching and sneezing may also occur. Causes of rhinitis can be a bacterial or viral infection or an allergic complaint. Seasonal rhinitis is also called hay fever because grass pollen is often the allergy trigger. Year-round symptoms are generally due to an allergy to dust mites, animal dander or mold.In addition, allergic rhinitis can also occur occupationally, for example as a reaction to vapors from paints or varnishes. A purely organic health problem of the nose is the congenital or acquired deviation of the nasal septum (septal deviation) due to injury. Although about 80% of all people have a slightly crooked septum, this generally does not cause any impairment. Only in the case of a severe curvature is free nasal breathing no longer guaranteed. In addition, the narrowed nasal cavity poses an increased risk of infection. The nosebleed (epistaxis) shows a mostly temporary symptom. Due to inflammatory, physical or chemical damage, a vessel of the anterior nasal septum almost always bursts. Only persistent, uncontrollable bleeding, often from the posterior nasal cavity, poses a greater health risk. Nasal furuncle and rhinophyma represent external pathologies of the nose. The former is a painful, deep inflammation of a hair follicle. Rhinophyma, or “cauliflower nose,” is a bulbous nasal growth associated with adult rosacea that worsens with tea, coffee, or alcohol consumption.
Typical and common conditions
- Stuffy nose
- Nasal polyps
- Sinusitis
