Example of sense of smell

Through the sense of smell we perceive the smells of what surrounds us. The sense of smell is found inside our nose, and from there it goes to the brain, where nerve impulses are interpreted.

The sense of smell is closely related to the sense of taste. On the tongue, only 5 basic flavors are perceived: sweet, salty, sour, bitter and umami. This information alone only allows us to accept or reject a food, but it does not allow us to differentiate, for example, the taste between a lemon and vinegar, or the taste of meat from that of a carrot.

The taste signals on the tongue are complemented by the olfactory sensations, which are produced when the smell of the food towards the front of the mouth towards the throat, from where it rises into the nasal cavity and reaches the receptors olfactory. It is a consequence of this combination of perceptions that we can distinguish the characteristic flavors of each food. This also affects when you have a cold or any disease of the upper respiratory tract, which totally or partially prevents the passage the air from the mouth into the nasal cavity, which causes the perception of the taste of food to decrease or apparently not have taste.

The elements that make up the sense of smell are the following:

The nostrils it is where the air enters with the molecules that produce the olfactory sensation.

The Nasal Cavity, which is the space that is filled with air every time we breathe, that is, it is the hole that exists inside our head through which the air of the breath passes. The nasal cavity is lined by epithelial tissue and by the so-called pituitary glands: The red pituitary gland and the yellow pituitary gland.

The red pituitary gland, which lines the lower part of the nasal cavity, covering the bony protrusions called turbinates. The red pituitary has many blood vessels, which heat the air that enters the nose; The mucus that keeps both the air and the nasal cavity moist, and helps to expel some foreign matter that enters with the breath, is also secreted there.

The olfactory bulb It is an extension of the brain that is located inside the skull, and it is the section in charge of transmitting olfactory perceptions to the brain.

The yellow pituitary gland It is located in the upper part of the nasal cavity, below the olfactory bulb. There are three types of cells that make up this pituitary: the basal cells, among which are the Bowman's cells, which are responsible for secreting fluid that cleans the olfactory area of ​​the nose; the support cells, which are epithelial cells that give shape to the whole and the olfactory cells, which are the endings of the olfactory cilia, which are the ramifications of the olfactory bulb that cross the floor of the skull, and are located in the upper part of the nasal cavity. There are seven types of olfactory cells, each of which is considered to perceive a particular type of odor: musky, camphor, ethereal, minty, spicy, floral, and putrid; the combination of the perceptions of these receptors allows us to distinguish around 10,000 different smells.

The area of ​​the yellow pituitary, responsible for capturing odors, is very small in humans, approximately 2cm x 2cm square. In other animals, such as dogs or cats, the cilia cover the entire cavity and sinuses, that is why they are more sensitive and have more olfactory acuity than we are.