Human sense of smell: how we are able to perceive smells

The human nose, namely the part of it that is responsible for smell, is the least studied in the human body. Scientists are still trying to establish all the physiological subtleties of this function of the human body. Some researchers believe that the ability to perceive smells is a vestige, that is, in the process of evolution, it has lost its functional importance for humans. However, it is the olfactory system that helps a person navigate in space, stimulate taste buds, and even determine if we have a physical attraction to a person. That is why the mystery of smell is another interesting and still not fully solved mystery of nature.

Structure of the olfactory system: odor receptors

Olfactory cells, which are scent receptors, are located in the olfactory region of the nose. This area is a 2.5 cm² area in the superior turbinate and superior nasal septum.  All these cells are bipolar neurons in their structure, and at the tips of their dendrites there are hairs immersed in the mucus of the nasal cavity. When chemicals are dissolved in this mucus, the olfactory receptors perceive them as a sense of smell. Olfactory cells are the primary receptors, the physiological mechanisms of activation of which lead to an increase in the perceived signal. Unlike the taste perception system, it is impossible to distinguish a small number of basic primary odors in the olfactory system. Probably,

Main pathways and centers of the olfactory system

The olfactory system differs fundamentally from other sensory systems: it lacks a spinal cord region and most of the olfactory pathways that lead to the cerebral cortex do not pass through the thalamus. The structure of the olfactory system is as follows:

The axons of the olfactory cells pass through the ethmoid bone in about twenty thin filaments that form the olfactory nerve and end in the olfactory bulbs;
from the olfactory bulbs, the olfactory pathways pass through the olfactory tracts;
then the olfactory pathways diverge in three directions:

to the medial olfactory region, which is the most ancient and is responsible for primitive reactions to smells, for example, excretion, licking saliva, and so on;
to the lateral olfactory region, which is responsible for complex behavioral acts;
into the orbital gyri of the frontal lobe, presumably responsible for the conscious perception of smells.

Interesting facts about smell:  How do people perceive smells

Since the sense of smell is not a fully understood sensory organ, scientists are still discovering many interesting facts related to this function of the human body. Here are some established interesting facts about the sense of smell:

it is with the help of scent receptors that people are able to capture each other's pheromones: individual chemicals produced by the body of each person. It is pheromones that make us be attractive to each other and cause sexual desire: the smell of the person you loved will never be confused;
the sense of smell is much better developed in women than in men: women are able to distinguish a much larger number of smells, however, the best perfumers, as it happened historically, were men;
The sense of smell changes during a woman's menstrual cycle: before and after ovulation, it becomes more acute, and women during this period react sharply to the aroma of male pheromones. This is not surprising, because it is during this period of the menstrual cycle that the probability of conceiving a child is highest;
The sense of smell of infants is highly developed, but in the first year the olfactory system loses its function by almost half. There is also atrophy of the olfactory fibers in the elderly;
the right nostril of a person perceives smells more acutely in right-handed people, while the left – lefties.

smell is the best way to tell if you really want to eat. If the smell of food does not seem too attractive – this means that the body is sufficiently saturated at the moment.