In the olfactory function in our body are responsible several structures, one can say that they are links in the system of smell. Violation of any of these links leads to the breakdown of smell.
First, it is the receptors in the nasal mucosa, they are located mainly in the nasal septum and turbinates on the lateral walls of the nasal cavity. Violation of their operation is possible with banal cold, due to mucosal edema. In addition, the mucosal lesions by inhalation of toxic substances such as accidental and intentional (eg, drug use) in these cases as possible reversible damage to the receptors and their overall death without renewal, and functions in the future.
The second link in the system are the olfactory nerve fibers conducting impulses from receptors in the brain. They may damage the trauma of the facial skull, especially the forehead and nose, as well as in inflammatory diseases of the maxillary and frontal sinuses. The third element is the area of the brain - the olfactory bulb, - where the analysis of the received pulses and the formation of a "smell".
It is interesting to note that this part of the human brain is one of the most ancient Bringing us to the animal world. In addition, the olfactory bulbs have a connection with the area of the brain responsible for emotional state, which explains the presence of pronounced emotional component in olfactory perception. Because of this connection with the odor causing pleasure or disgust, you can purposefully change the state of the organism, this feature is used, for example, in aromatherapy. If the damage olfactory bulbs can be used either symmetric or one-sided loss of smell.
Especially important for the diagnosis of the level of destruction is the loss of one-sided - it indicates, as a rule, to defeat it is the bulbs. The most common cause of unilateral loss or reduction of the olfactory bulb is a tumor, as well as the pituitary gland, which is located near the brain. Often the cause of loss of smell is traumatic brain injury, the reverse recovery of function is a long time - within six to twelve months. Sometimes the loss of smell may be diabetes, as well as in some endocrine congenital syndromes. In addition to loss of smell may be such a breach, as a distortion in the perception of odors, as well as pathological sensation of odors at their real absence. These disorders are often manifestations of olfactory illusions and hallucinations occur in lesions and brain structures, so they can be observed in the epileptic seizures (seizure aura).
Treatment of disorders of smell should be in accordance with the primary reason for its occurrence.