Olfactory sense


The olfactory portion of the cerebral cortex receives the necessary information to determine and discern smell via olfactory receptors. These are the dendritic ends that belong to the olfactory nerve and respond to chemical stimuli. This information is then sent directly to the brain for interpretation.

Nature has determined that the human olfactory sense is the least important sense of the human body. Nature determined this when she created much stronger olfactory senses in other creatures, and enabled them to find food, water, and shelter through the act of sniffing.


Humans rely on sight, sound, and dexterity more than they rely on smell for basic survival skills. The human sense of smell detects odor, but does not discern its actual intensity.

Accommodation occurs quickly when considering the sense of smell. Olfaction and gestation (the sense of taste) are rather similar to each other as they each need the chemical stimuli to dissolve in order for them to react. This, by definition, categorizes them as chemoreceptors.


Olfactory sense
Image: Olfactory Sense

The nasal mucosa rests within the roof of the nasal cavity. It can be found along both sides of the nasal septum. This is where the olfactory cells are located. The glandular goblet cells which surround the olfactory cells help to provide the necessary moisture for effective olfactory cell function. In between the supporting columnar cells there are the cell bodies of the bipolar olfactory cells. Olfactory hairs are the sensitive segment of the receptor cell, which is created by the dendrite ends of the free ends of each olfactory cell. These ends are unmyelinated and are quite responsive each time airborne molecules make their way into the nasal cavity.


There are in fact, numerous neural segments which in turn create the sensory pathway of olfaction. It begins with the unmyelinated axons of the olfactory cells, which conjoin to create the olfactory nerves. The olfactory nerves travel along, through the foramina of the cribriform plate where they finally come to and end in the olfactory bulbs, which are created by grey and white matter.

On either side of the crista galli of the ethmoid bone, the olfactory bulbs can be located just beneath the frontal lobes of the cerebrum. Neurons which belong to the olfactory nerves synapse with dendrites which are just beginning to form the beginning of the olfactory tract. This happens inside the olfactory bulbs. The olfactory tract is responsible for directed the sensory impulses to the cerebral cortex. Within the cerebral cortex, the impulses can then be discerned as smell, aroma, or scent.


Olfactory senses can be heightened to be able to discern thousands of distinct smells. People who work as perfume testers are trained to understand their fine sense of olfaction. This varies from the senses, like the sense of taste, which can only be distinguished as four basic modalities. There is still a great deal to be studied and learned in regards to the molecular basis of olfaction. What is known however, is that it only takes one odorant molecule to enter the nasal cavity for an olfactory receptor to respond.
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