Olfaction

Question 1

What kinds of substances can activate olfactory receptors?

Answer 1

only mucus-soluble substances

Question 2

the olfactory nerve is which CN?

Answer 2

CN1

Question 3

Axons from the olfactory receptors travel through the ______ to the ________.

Answer 3

through the cribiform plate to the olfactory bulb

Question 4

Where is the olfactory epithelium located?

Answer 4

in the upper regions of the nasal cavity

Question 5

Receptors have a life span of _______ and are replaced by ______.

Answer 5

life span of 1-2 months and are replaced by basal stem cells

Question 6

How many types of odorant receptor cells to humans have?

Answer 6

about 300 types- each receptor responds to only one odorant

Question 7

How do odorants trigger APs in their respective receptor cells?

Answer 7

odorant binds receptor on microvilli –>opens Na/Ca channel –> opens Cl channel (outward flow) –>depolarization

Question 8

What is sensory adaptation and what kind of chemical mediates those pathways?

Answer 8

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

Question 9

Axons of receptor cells that respond to the same odorant converge in the olfactory bulb and synapse with what type of cell?

Answer 9

a mitral cell for that specific odorant

Question 10

The olfactory bulb projects axons to _______, which then projects information to the _______, _______ and ______.

Answer 10

projects to the piriform cortex, which then –> amygdala, hippocampus and prefrontal cortex

Question 11

where is the piriform cortex?

Answer 11

medial surface of the temporal lobe

Question 12

What are three things that the piriform cortex does?

Answer 12

consciousness of odors, singularity and habituation

Question 13

How many odors can we consciously recognize at once?

Answer 13

1-3

Question 14

What is one benefit of cortical habituation?

Answer 14

perception of odorants in the background of a currently present odorant

Question 15

What does the amygdala do with olfactory information?

Answer 15

generates emotion and associative learning around a scent, also projects to the hypothalamus to generate autonomic and endocrine responses to scent

Question 16

What kind of responses do we have to citrus fragrances?

Answer 16

increased immune function, improved psychological states

Question 17

What kind of responses do we have to rose fragrance?

Answer 17

inhibits stress-induced skin barrier disruption, elevates salivary cortisol

Question 18

What kind of responses do we have to orange and lavender frangrances?

Answer 18

reduced anxiety

Question 19

What does the hippocampus do with olfactory information?

Answer 19

puts it into episodic long term memory

Question 20

What does the orbitofrontal cortex do with olfactory informaiton?

Answer 20

functions with the amygdala, as well as associates with taste for reward values of food. emotion, associative learning, evaluation of odor.

Question 21

What is a danger of the olfactory bulb? What is a pharmaceutical benefit?

Answer 21

it’s an easy way for pathogens to spread from the externa to the CNS. Insulin can be administered intranasaly.