Morphology of the Human Olfactory Analyzer

Abstract

The sense of smell provides people with valuable information about the biochemical environment and their own body. Olfactory disorders occur in pathologies of the nasal cavity, liver cirrhosis, psychological and endocrine diseases. Smell affects various psychological aspects of people's lives, forming positive and negative emotional memories associated with smells. With the dysfunction of the olfactory analyzer, a person will not do the analysis whether the food is good, will not be able to feel the presence of poisonous gases in the air, bad breath. This puts a person in an awkward position and increases the risk of social isolation. The purpose of the study was to highlight the components of the normal structure and functioning of the human olfactory analyzer. Identification of odors in the environment and from one's own body is provided by the olfactory analyzer. Primary odors as camphor, floral, fruity, spicy, tarry, burnt and putrid in different quantities form secondary odors. Aromas are composed of volatile molecules called odorants. The smallest amount of odorant that causes an odor sensation is called the odor threshold. In people with coronavirus disease the sense of smell temporarily disappears (anosmia); it is reduced (hyposmia) in liver cirrhosis and rhinitis, and in Alzheimer's disease and schizophrenia besides hyposmia there is olfactory hallucination (phantosmia). Olfactory dysfunction adversely affects children's cognitive abilities. Fragrances change emotions and behavior. Aromas are used to regulate the physical and psychological state of the patient. Volatile molecules of fragrances penetrate through the layer of mucus that covers the olfactory epithelium located in the olfactory region of the nasal mucosa. The olfactory epithelium consists of olfactory, supportive and basal epitheliocytes, as well as secretory cells of the olfactory glands. Olfactory cells are modified nerve cells that have a body, an axon, and a dendrite, which ends with a receptor in the form of olfactory cilia. Volatile molecules interact with the olfactory cilia and then with the receptor protein, which is located on the olfactory cell bodies. In humans, olfactory cells have 350 receptor proteins. One type of receptor can register molecules of several different odorants. Molecules of the same odorant can activate several different receptors simultaneously. The nerve impulse from the olfactory cells (bodies of I neurons) reaches the nerve cells (bodies of II neurons) of the olfactory bulbs via their central outgrowths (olfactory filaments). Axons of nerve cells of olfactory bulbs continue to bodies of III neurons, which are located in subcortical centers of the brain (almond-shaped body, nuclei of the transparent septum). In human, to analyze a particular odor, axons from bodies of III neurons continue to cortex, namely to the area of the uncus of the parahippocampal gyrus