What is our nose for?
Our nose functions as a central axis of the face from a cosmetic aspect and also a highly efficient organ that both conditions the air we breathe and aids with our sense of smell. When we have nose infections, allergy or a deviated septum, these can lead to a blocked nose, a runny nose, nasal congestion, smell loss and even ear problems such as a blocked ear.
From a functional perspective, the nose conditions the air that we breathe such that it is in an appropriate state for our lungs to be able to extract oxygen. This conditioning occurs through the shape and lining of the inside of the nose which warms, filters and humidifies the air we breathe in (inspiration). The nasal passages extend horizontally backwards for about 8-10cm and within this very short pathway, the air has been warmed from room temperature and humidity to almost 34 degrees centigrade and close to 100% humidity.
Conversely, when we breathe out (expiration), the nose “recovers” the warmth and humidity from the air to prevent loss of heat and water from our body. In particular, there are three swellings on the outer wall of the nasal passageways. These are called the nasal turbinates and they swell and shrink every few hours to control and direct airflow within the nose such that most of the time we are able to breathe through one nostril more than the other with the side alternating in concert with the alternating swelling of the turbinates.
In the diagram below, asterisks show the location of these turbinates.
As well as conditioning the air, the turbinates direct airflow towards the roof of our nose where there are specialised nerve endings that help us smell (a process termed olfaction).