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Anatomy of Smell |
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Smell anatomy [online image] http://wps.aw.com |
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At the top of each nostril, there is a region called the nasal mucosa. This area holds a layer of pseudostratified epithelium called the olfactory epithelium. The olfactory epithelium is about five square centimeters in humans, and is covered in mucus. It contains both sensory cells and Bowman's glands. |
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nasal cavity [online image] http://www.cf.ac.uk/biosc/staff/jacob/teaching/sensory/olfact1.html |
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Bowman's glands produce the secreation that covers the receptors. The secreation contains mucopolysaccharides, immunoglobulins, protiens, and enzymes. (white dotted line surrounds bowman's gland in picture) |
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Bowman's gland [online image] http://www3.umdnj.edu/histsweb/lab10/lab10olfactory.html |
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The olfactory epithelium contains the olfactory receptor neurons. These neurons are bipolar, meaning they have one axon and one dendrite. The neuron ends in a dedrite knob from which 8-20 cilia dangle. The axon of the neuron terminates in the olfactory bulb. These neurons are the only ones that are regularly replaced in the body. |
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neuron [online image] http://www.cf.ac.uk/biosc/staff/jacob/teaching/sensory/olfact1.html |
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Another type of cell found in the olfactory epithelium are columanr shaped supporting cells. These pigmented cells account for most of the bulk of the epithelium. Also found in the epithelium are short basal cells that are the source for new receptors. |
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epithelium [online image] http://www.unmc.edu/physiology/Mann/pix_4b/olf_receptors.gif |
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The olfactory bulb is the bulb like end of the olfactory lobe. It lies on the cribiform plate at the end of the olfactory tract. It contains clusters of axons called glomeruli that recieve direct input from the olfactory receptor cells. These glomeruli connect to other neurons in the olfactory bulb called mitral cells. |
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bulb [online image] http://www.colorado.edu/epob/epob3730rlynch/image/figure8-18.jpg |
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Next: Physiology of Smell |
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