The nostrils are nothing other than the nostrils . It seems like a small thing, but the nostrils are the gateway to the nostrils and the first area that molecules must pass through in order to stimulate olfactory receptors. The two nostrils are separated by the skin that covers the nasal septum.
The nose is the outer appendix of the nostrils , which communicate with the environment through the nostrils. Following the nostrils, as we enter the nostrils, there is a sagittal septum that separates them and, in the rest the hole, the mucosa is covered with hairs that perform a first function of physical filtering of impurities. These internal nasal hairs act as the primary barrier of the immune system , similar to the way the skin does.
The nostrils exist to perform a function of filtering the air but also to heat the inhaled air, by exchanging heat with the body temperature as they move inwards through a non-linear path. From an immunological point of view, the nose is where mucus is expelled that can carry dead leukocytes or bacteria. The sneeze reflex occurs when the lining of the nasal passages becomes irritated, and has a defensive and excretory purpose.
Returning to the anatomy of the nasal passages and their main function, that of tempering and moistening the air that is going to pass through the pharynx, larynx and other structures of the respiratory system, it is necessary to point out the existence of turbinates or internal bone structures, which make that the path that the air travels is more tortuous and allow to improve the heat exchange if necessary.
The main physiological function of the nasal passages continues to have immunological value, protecting the mucosa in organs such as the larynx and trachea. Ultimately, the nostrils and nostrils are able to filter most of the environmental solid particles with one exception: asbestos (known as asbestos), microscopic and elongated solid particles that manage to penetrate to the pulmonary alveoli, causing irreversible injuries with continued exposure .
Smell: an essential sense for survival
Most of the nasal passages are covered by what is known as the red pituitary , with cells responsible for secreting mucus. In the upper part of the nostrils the yellow pituitary is located, where the olfactory nerve cells are. These nerve cells are stimulated by contact with certain volatile molecules, such as terpenes and aromatic or benzene rings, triggering a response that ends with the perception of what we know as smell or aroma by the brain. In reality, aromas are often perceived in combination with other signals captured by the digestive system, in the mouth (the aftertaste), although in a colloquial way smell and aroma are synonymous.
The sense of smell was decisive in our ancestors not only to perceive dangers, but to distinguish that some things like carrion are not edible for humans.
There are diseases that permanently affect smell, while others such as the typical cold can block this sense for purely physical reasons (acute rhinitis). Despite everything, smell is still an important sense for the human being, related to memory and the limbic system.
In summary, the nostrils are the gateway to the respiratory system , although it is also possible to breathe through the mouth, and the olfactory system. After what appear to be two simple holes, we enter a series of unique structures and tissues in our body, with very specific physiological functions.
