That protuberance on our face that identifies or defines our origins ie. genetics & gives us a sense of pride or shame, in itself it is an emotional organ, eliciting emotional responses & responding to our emotions physiologically by running and or blocking. It also defines our sexuality, often being labelled a masculine or a feminine nose.
Looking beyond the external appearance of our noses it can be considered the protector – Filtering & trapping, humidification, olfaction. (Olfaction – our sense of smell -to be covered in a later post).
When breathing in air, this air filled with pollutant particles, bacteria, viruses & allergens (microscopic particles like pollen that have the ability to cause an immune reaction), is firstly filtered by our nasal hairs. Yes, those very hairs that we often feel are unsightly & trim, have a very important purpose.
Thereafter smaller particles are trapped in what we term the mucous blanket, a thin layer of mucous found within the nasal cavity that traps smaller microscopic particles and then it is the microscopic cilia that sweep this mucous with all the trapped impurities, particles & organisms backwards to the back of the nose & down the throat to be swallowed, so entering the digestive tract where they are destroyed due to the acidity of the stomach & so are unable harm us.
Linked to the filtration function of the nose is humidification.
Consider the fact that we breathe 6 to 7 L of air in a minute at rest and this would increase significantly with exercise to 50-60 litres a minute for strenuous exercise. All this air needs to be humidified to protect the intricate fragile internal structures of the lungs where oxygen exchange takes place i.e. the alveoli. The nose needs to work efficiently as a humidifier and uses approximately 1 and a 1/2 litres a day to fulfil this purpose. To ensure that this amount of liquid is available, it is important to make sure that we are well hydrated and this can be done by drinking water or steaming, breathing in and out through the nose.
As a result of some turbulence within the air flow through the nose, structures in the nose called the turbinates which are incredibly vascular structures warm and humidify the air we breathe in. Regardless of the environment we live in, across the earths diverse climates the nose adjusts the temperature of the air we breathe in, close to normal body temperature and humidifies the air to about 98% humidity.
Breathing out through the nose much of the moisture and heat in the expired air is reclaimed in the nasal cavity by the nasal turbinates, to humidify the air that is breathed in again, (inspired air), in the next breath and so on.
If one breathes out through the mouth, as in strenuous exercise, then this moisture is lost and more water will be required by the body not only to replenish the water lost due to sweating but the water not reclaimed by the nasal structures due to mouth breathing.
We all experience that very dry mouth when we breathe in and out through our mouths when our nose is blocked. Although it is claimed that the pharynx i.e. the back of the throat which is usually moist, contributes to humidification of inhaled air it certainly is not as efficient as the nasal cavity.
Interestingly what we assume to be a very efficient system pales in comparison to the efficiency of the humidification in mammals.
We take the efficient functioning of the nose for granted until we are symptomatic, as in the complaint of a post nasal discharge.