Olfaction Flashcards
What kinds of substances can activate olfactory receptors?
only mucus-soluble substances
the olfactory nerve is which CN?
CN1
Axons from the olfactory receptors travel through the ______ to the ________.
through the cribiform plate to the olfactory bulb
Where is the olfactory epithelium located?
in the upper regions of the nasal cavity
Receptors have a life span of _______ and are replaced by ______.
life span of 1-2 months and are replaced by basal stem cells
How many types of odorant receptor cells to humans have?
about 300 types- each receptor responds to only one odorant
How do odorants trigger APs in their respective receptor cells?
odorant binds receptor on microvilli –>opens Na/Ca channel –> opens Cl channel (outward flow) –>depolarization
What is sensory adaptation and what kind of chemical mediates those pathways?
decreased receptor cell activity after prolonged exposure to an odorant. mediated by Ca independent and dependent pathways, causes receptors to be inhibited and channels to close
Axons of receptor cells that respond to the same odorant converge in the olfactory bulb and synapse with what type of cell?
a mitral cell for that specific odorant
The olfactory bulb projects axons to _______, which then projects information to the _______, _______ and ______.
projects to the piriform cortex, which then –> amygdala, hippocampus and prefrontal cortex
where is the piriform cortex?
medial surface of the temporal lobe
What are three things that the piriform cortex does?
consciousness of odors, singularity and habituation
How many odors can we consciously recognize at once?
1-3
What is one benefit of cortical habituation?
perception of odorants in the background of a currently present odorant
What does the amygdala do with olfactory information?
generates emotion and associative learning around a scent, also projects to the hypothalamus to generate autonomic and endocrine responses to scent
What kind of responses do we have to citrus fragrances?
increased immune function, improved psychological states
What kind of responses do we have to rose fragrance?
inhibits stress-induced skin barrier disruption, elevates salivary cortisol
What kind of responses do we have to orange and lavender frangrances?
reduced anxiety
What does the hippocampus do with olfactory information?
puts it into episodic long term memory
What does the orbitofrontal cortex do with olfactory informaiton?
functions with the amygdala, as well as associates with taste for reward values of food. emotion, associative learning, evaluation of odor.
What is a danger of the olfactory bulb? What is a pharmaceutical benefit?
it’s an easy way for pathogens to spread from the externa to the CNS. Insulin can be administered intranasaly.
