The nasal cavity mainly has respiratory and olfactory functions, in addition to filtering and cleaning, absorption and excretion, heating and humidification, resonance and reflexes. In addition, the epithelium of the nasal mucosa can secrete a series of bioactive substances such as lysozyme and defensin, which have certain biological roles.
Physiological functions of the nasal cavity: 1. Respiratory function (1) the portal and channel of the respiratory tract. Respiratory airflow for the contact between the body and the outside world its important role. External gas inhalation nasal cavity, through the regulation of a series of physiological mechanisms of the nasal cavity, in line with the needs of the body exchange into the lung organs. Otherwise, it is easy to cause respiratory diseases. External airflow for arriving at the nasal cavity, after processing for exchange into the lungs, for gas exchange.
(2) nasal resistance has an important role in maintaining negative thoracic pressure, facilitating the full stay of airflow in the alveoli, and ensuring the realization of normal respiratory function. Nasal airway resistance (nasalairwayresistance (NAR)) accounts for about half of the overall airway resistance. The value of nasal resistance varies with the change of physiological state and pathological state, and the disease varies with age and ethnicity. In normal people, the blood vessels in the mucosa of the inferior turbinate on both sides are alternately contracted and diastolic, which manifests as periodic changes in the opening and closing of the nasal airways bilaterally, called the nasal cycle. The nasal cycle is influenced by alternating excitation and inhibition of the right and left sympathetic nerves and should not be detected under normal circumstances. The nasal cycle varies widely among individuals, ranging from 2 to 6 hours in healthy individuals. The nasal cycle has an effect on unilateral transient nasal resistance, but does not affect total nasal airway resistance. The presence of nasal cycle is beneficial to relieve fatigue and enable timely and repeated adjustment of sleep position during sleep.
(3) Regulation of temperature and humidity. Since the nasal mucosa covers an area of about 160 cm2, the capillaries and glands within the mucosa are abundant and play a role in the regulation of temperature and humidity. And it is related to the temperature, humidity, quantity, speed and nature of secretions (plasmacy, mucus and septic) of inhaled nasal gases.
(4) Filtering and cleaning effect. Nasal hairs have the ability to block dust particles and bacteria in the external airflow, airflow purification process. And the nasal mucosa cilia system is an important tissue to maintain the normal physiological function of the nasal cavity, play an important role. Changes in the rheology of body fluids on the mucosal surface have changes on it, and are affected by a variety of factors such as dryness, osmotic pressure, temperature, acidity and alkalinity, and drugs.
2, olfactory function: smell is a complex psychological and physiological response, and also a protective function of the nasal cavity. There are many factors affecting it, such as gender and age, local mechanical pressure, local and systemic infections and long-term inhalation of harmful gases. The severity can be divided into hyposmia and loss of smell.
Reflexes: The nerves in the nasal cavity are richly distributed and can cause respiratory and cardiovascular effects when the mucosa is mechanically, chemically or physically stimulated. Mainly includes: nasopulmonaryreflex, sneezereflex, nasocardial reflex, nasociliary emission, and olfactory reflex, the increase and decrease of body surface temperature will lead to congestion and swelling of nasal mucosa.
4, absorption function: the rich blood microcirculation in the nasal mucosa is its important anatomical basis.
5, tear drainage function: nasolacrimal duct is the way of tear drainage and excretion in the regular state, opening in the lower nasal tract.
6, immune function: secretion of specific immune substances (immunoglobulins, etc.) and non-specific immune substances (lysozyme, lactoferrin, proteolytic enzymes, etc.), play immune mechanisms.