Olfactory receptors are located in the upper portion of the nasal passages. Each part of the nasal cavity has olfactory area of 2-5 cm 2 (fig. 182).

Olfactory system structure

Olfactory receptors are located in the upper portion of the nasal passages. Each part of the nasal cavity has olfactory area of 2-5 cm2 (fig. 182). There are more than 10 million olfactory receptor cells (dogs have more than 200 million) in it, which are located between the support cells (diagram 183.). Olfactory receptor cells are shaped like a jag with a long neck. One end of the cell has at 6-12 very thin hairs, which increase the contact surface of receptors with odorous substances molecules in ten times. In addition, they move and actively "catch" the odorous molecules. Hairs are immersed in mucus that is produced by nasal mucosa glands. Some odorous molecules pass mucus quickly, others — more slowly, some delay longer (filter). At the other end of the "jar" are axons that form the olfactory nerve fibers.

Diagram 182. The structure of the olfactory system: signals about each molecule proceed via the olfactory nerve (2) from the olfactory receptor area (1) to the olfactory bulb (3), wherein they are pre-analyzed. Then this information delivers in subcortical regions (e.g. thalamus (4), hypothalamus) of the brain, analyzes again and finally falls into the superior parts of the olfactory system (5), where forms the final image of the olfactory
Diagram 183. The structure of the nasal mucous membrane at the location of the olfactory receptors (in the olfactory area): 1 — olfactory bulb; 2 — olfactory neuron; 3 — dura; 4 — ethmoid bone; 5 — glands that produce mucus; 6 — basal cell; 7 — cell receptor; 8 — supporting cell; 9 — air flow; 10 — odorous molecules; 11 — cilia
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Questions:
  • Define the structure of the nasal mucosa in the olfactory area.