The Olfactory System Flashcards
Olfactory Epithelium
Structure
Specialized area in the olfactory mucosa located in the roof on the nasal cavity on the inferior surface of the ethmoid bone.
Covered by a superficial acellular layer of mucus that contains proteins that can bind oderants
Olfactory Epithelium
What is the structure of the olfactory receptor neurons? (name the regions and their functions)
They are bipolar cells - they can REGENERATE
They have APICAL DENDRITES which extend to the surface of the epithelium and terminate in round olfactory vessicles from which 10 to 30 CILIA arise
The cilia project into the overlying mucus and contain RECEPTORS for oderants.
The basal axon extends from the cell body in the other direction in bindles called fila. the fila pass through the cribiform plate to terminate in the olfactory bulb.
Together, the fila make up the olfactory nerve.
this is where OLFACTORY TRANSDUCTION occurs.
Olfactory Epithelium
What is the structure and function of the supporting cells in the olfactory epithelium?
They are columnar cells located adjacent to the olfactory receptor neurons.
They provide mechanical support for olfactory receptor neurons and add secretions to the mucus layer that might play a role in binding or inactivating oderant molecules
Olfactory Epithelium
What is the structure and function of the basal cells in the olfactory epithelium?
They are neural stem cells located at the base of the olfactory epithelium.
They give rise to olfactory receptor neurons
What are the steps in olfactory transduction?
1) oderants are transported through the mucus by oderant binding proteins
2) oderands bine to METABOTROPIC receptors on the cilia of the apical dentrites, opening K+ and Ca+ channels so that the cell depolarizes
3) the depolarization travels down the dendrite to the cell body, where are large enough depolarization initiates an action potential
How do we discriminate between oderants?
Individual olfactory receptor neurons are sensitive to only one type of oderant.
Specific SUBTYPES of oderant receptors preferentially distribute within one of 4 bilaterally symmetric zones of the olfactory epithelium.
This indicates that there is some mapping, but we are still not sure what it is or what it indicates
What are the 4 features unique to the olfactory system?
olfactory cortex is 3 layered
the pathway does not project to the thalamus before the cortex
perception occurs at the orbitofrontal cortex rather than at the olfactory cortex
cells of the olfactory epithelium regenerate
