Olfactory cell
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Smell cells are the sensory cells of the sense of smell . They are located in the olfactory mucous membrane as special regions of the nasal mucous membrane and are equipped with specific receptors for the detection of odorous substances. In humans there are 200 to 400 types with different olfactory receptors and a total of around 10 million olfactory cells.
As primary sensory cells, olfactory cells are also nerve cells . Their dendritic process reaches the mucus-covered epithelial surface . From its vesicular expansion, vesicula olfactoria (also called olfactory bulbs ), several cilia arise , in humans about 5–20, which spread parallel to the surface in the mucus of the olfactory mucous membrane. These cilia of an olfactory cell have specific receptor proteins embedded in their membrane for the absorption of stimuli.
After the appropriate contact between the molecule of an odorous substance and the specific molecule of an odor receptor protein, the stimulus is converted into an electrical signal in the chemosensory cilia . These signals are collected in the cell body and passed on as action potential series via the neurites of an olfactory cell to the brain, initially to other nerve cells in the olfactory bulb (olfactory bulb). Here, the neurites of a certain type of sensor of the same kind from olfactory cells then each form synapses in a ball-like glomerulus olfactorius .
On their way there, the processes of the olfactory cells pass as fila olfactoria (olfactory threads) through fine holes in the ethmoid bone of the skull; they are not myelinated and therefore have a low conduction velocity of about 20 cm / s.
literature
- Werner Linß, Jochen Fanghänel : Histology: cytology, general histology, microscopic anatomy . Walter de Gruyter 1998, ISBN 9783110140323 , p. 137.
