5.2 Olfaction

Question 1

pheromones

Answer 1

excreted or secreted chemicals that trigger a social response in another individual of the same species when preceived by the olfactory system.

Question 2

odorants

Answer 2

A molecule conducted through the air that leads to activation of the olfactory receptors and may be perceived as having a fragrance when processed through the olfactory system

Question 3

nasal cavity

Answer 3

The human sense of smell uses the input from odor receptors embedded in the mucous membrane of the roof of the nasal cavity to discriminate among odorants. There are tens of thousands of odorants and over a thousand types of receptors: most receptors respond to only a limited number of odorants, though a single odorant can bind to more than one type of receptor.
Another hypothesis is that the molecular vibrations of groups of odorant molecules contribute to odor recognition. This model predicts that odorants with similar vibrational spectra should elicit similar olfactory reponses, and it explains why similarly shaped olfactory molecules with dissimilar vibrations have very different fragrances.

Question 4

bipolar neurons

Answer 4

The olfactory receptors are called bipolar neurons because appendages extend from opposite sides of their cell bodies.

Question 5

glomeruli

Answer 5

When odorant triggers a receptor, they send a signal to the glomeruli, the neurons in the olfactory bulb. The axons from the glomeruli then exit laterally from the olfactory bulb, forming the olfactory nerve. Their destination is the primary olfactory cortex.

Question 6

Primary olfactory cortex

Answer 6

located at the ventral junction of the frontal and temporal cortices

Question 7

olfactory pathway, unique in two ways

Answer 7

1. Most of the axons of the olfactory nerve project to the ipsilateral cortex
2. The olfactory nerve arrives at the primary olfactory cortex without passing through the thalamus. The POC projects to a secondary olfactory area and makes connections with other brain regions.

Question 8

primary olfactory cortex vs secondary olfactory cortex

Answer 8

research has shown that the primary olfactory cortex might be essential for detecting a change in the external odor and that the secondary olfactory cortex might be playing an important role in identifying the odor itself.