Olfaction - Fitz & Michaels

Question 1

How many olfactory recptor proteins are there?

Answer 1

about 1000

Question 2

True or false

There is actually an odourtypic map found in the olfactory bulb, similar to the humunculus in the somatosensory cortex!

Answer 2

True

Question 3

One thing that makes the olfacotry system unique is that there are no specialized receptor cells like in the other special senses…

If this is the case, where are the receptor proteins?

Answer 3

Receptor proteins are on the olfactory receptor neurons themselves

Question 4

List the 4 main steps to produce olfactory transduction:

Answer 4

1 Activate receptor protein
2 Activate G protein (G-olf)
3 Stimulate adenylate cyclase to increase cAMP
4 cAMP opens nonselective cation channel to let in Na+, Na+ then depolarizes the cells and causes a receptor and action potential to follow

Question 5

How is pattern coding used to dinstinguish many different smells from one another?

Answer 5

Each chemical can stimulate mutliple receptors

By analyzing the pattern of stimulation the brain can put things together

Question 6

What cortex is the primary olfaction cortex?

Answer 6

The piriform cortex

Question 7

List the main areas of the brain where the primary olfactory bulb projects its fibers:

Then explain how these areas are relating to olfaction:

Answer 7

Olfactory bulb ->
Olfactory tubercle/amygdala -> hypothalamus
-This then mediates visceral reactions and homestasis Ex. Food smells and gastric acid

Piriform cortex -> MD Thalamus -> Orbitofrontal

• This then mediates conscious perception of smell
• Produces “flavor”

Entorhinal Cortex -> hippocampus
- This then relates to memories