Olfaction

Olfaction is the sense of smell. This sense is mediated by specialized sensory cells of the nasal cavity of vertebrates, which can be considered analogous to sensory cells of the antennae of invertebrates. In humans, olfaction occurs when odorant molecules bind to specific sites on the olfactory receptors. These receptors are used to detect the presence of smell. They are found in the olfactory epithelium (part of the nasal epithelium).

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Anatomy of the olfactory system

The olfactory system is the sensory system used for olfaction. Most mammals and reptiles have a main olfactory system and an accessory olfactory system. The main olfactory system detects airborne substances, while the accessory system senses fluid-phase stimuli.

Olfactory epithelium

The olfactory epithelium is a specialized epithelial tissue inside the nasal cavity that is involved in smell. In humans, it measures about 1 square centimeter (on each side) and lies on the roof of the nasal cavity about 7 cm above and behind the nostrils. The olfactory epithelium is the part of the olfactory system directly responsible for detecting odors.

Olfactory bulb

The olfactory bulb is a neural structure of the vertebrate forebrain involved in olfaction. The olfactory bulb transmits smells from the nose to the brain, and it is one of the first regions of the brain to pick up on smells.

Olfactory perception

Olfactory perception is different from other forms of perception. The main difference is that the brain can identify a specific smell and recall it even after a long time. This is because the olfactory system has a direct connection to the hippocampus, which is responsible for memory and emotion.

Disorders of olfaction

Disorders of olfaction can be due to a number of reasons, including aging, genetic disorders, sinus disease, and exposure to toxins. The most common disorder is anosmia, which is the inability to perceive odor.

See also

• Anosmia
• Olfactory system
• Olfactory bulb
• Olfactory epithelium

Olfaction Resources
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