Why are we advised not to breathe through our mouth?
Two important functions of the nose are, as a respiratory passage and organ of smell. Receptors for smell are placed in the upper one-third of nasal cavity and this part is lined by olfactory (related to smell) mucosa. Rest of the nasal cavity is lined by respiratory mucosa.
Filtering or cleaning functions of the nose are carried out by hair in the nostrils, mucous blanket covering the nasal cavity and the cilia present in the nasal epithelial covering.
Hairs in the nostrils strain out many foreign particles greater than100 micrometres. Most of the remaining particles of this size are settled on the mucous membrane of the nose and the throat. ‘Mucous blanket’ is a sheet of secretion of mucous secreting glands of the nose.
This blanket traps the foreign particles which are removed. Particles of size 2-10 micrometres entering the lower airway are also removed away from the lungs by the ‘ciliary escalator’ which is present from nose up to the lower airways.
When ciliary motility is defective, mucous transport is virtually absent and this leads to chronic sinusitis and recurrent lung infections. Nasal mucosa can cool or warm the inspired air so that very hot or very cold air is at or near the body temperature by the time it reaches the lungs. Relative humidity of the atmospheric air depends on various climatic conditions.
Air is dry in winter and saturated with moisture in summer. Nasal mucosa adjust the relative humidity of the inspired air to 75 per cent or more. Water to saturate the air is provide by the serous and mucous secretions. Curved bony projections from the inner side of nose called as nasal conchae or turbinates play a significant role in the above said functions of the nose by providing a larger surface area.
Nasal breathing also has a vital role in preserving the oro-facial structural and functional harmony.
Mouth breathers breath orally even in relaxed and restful situations. To begin with, new born child is an obligatory nasal breather. Mouth breathing is an acquired habit which is learnt either as a mere habit or due to various anatomic reasons like obstructing nasal airway or short upper lip.
Oral breathing causes drying of gums (gingiva) of the upper front teeth and this predisposes to redness, swelling and easily bleeding tendency of gums called as gingivitis. Saliva is evaporated due to continuous airflow through the mouth which will lead to dryness and promotes dental decay(dental caries).
Dr. SHAHNAS BEEGAM K.