Olfactory Pathways And Olfaction Flashcards
How many odarants can we distinguish?
10,000
Is olfactory a special sense?
No
The neurons are simple but the process is weird
How many different genes are involved in olfactory receptors?
Around 330
Where are the receptor proteins for olfaction located?
On the dendrites of the olfactory neurons in the olfactory epithelium
This breaks the special sense rule
The will also be replaced unlike other senses
What type of neurons are in the olfactory tract?
Bipolar
What is the four step mechanism to opening special binding proteins in the nose mucus?
- Activate a receptor
- Activate G protein golf
- Stim adenlylate cyclase, up cAMP
- cAMP opens ligand gated channel
This then allows sodium to travel in the cell
What is the receptor organization in the nose mucus?
None, it is totally random
However, the signals are trafficked and we have an odortypic map
Classic example of pattern coding, in the receiving end
Explain pattern coding in respect to smell?
Each Oder has it’s own pattern of receptors it triggers
A map exists at the olfactory bulb
How much of the olfactory process goes through the thalamus?
Not much
What is the second order neuron in the olfactory system?
Mitral cells that form the tract
What can happen to axons in the cribiform plate if you get into a car accident? (Mitral)
They can get sheared off
Can kinda recover but often times there is no recovery
What is the end point of the olfactory tract?
Unconscious parts
Goes to olfactory cortex
Amygdala (corticomedial nuclei) Uncus Hippocampus Entorhinal cortex (Alzheimer's) Hypothalamus Thalamus (conscious part)
What does the olfactory tubercle project to?
The amygdala which is in the uncus
Drive and strong emotions
Where does the entorhinus area project?
The hippocampus
Where does the pisiform cortex go to?
The medial dorsal nucleus of the thalamus
In the upper right corner
Where does information from the olfactory tubercle at the base of the tract go and do?
The amygdala, to the hypothalamus
Visceral response to smell
Get things revved up, GI
Sex drive
Aversions
Where does info from the Entorhinal cortex go and do?
The hippocampus (eventually to the mammillary bodies) This is for memories
What does the piriform cortex do?
Primary olfactory cortex
Either to the MD nucleus of the thalamus and then to the orbital frontal cortex (conscious perception)
Or straight to the orbital frontal cortex
Where do taste and smell integrate into flavor?
The MD nucleus of the thalamus then to orbital frontal cortex
