CNS- FA17- Olfactory System Flashcards
Since the olfactory is an older system, is it more or less organized?
Less organized
How is the olfactory system different from other sensory systems?
- Nontopographical
- Olfactory neurons/olfactory Receptors are modified epithelial
- Replaced every 1-3 months
The mucosa cells are replaced how often?
Every month
This is because when air comes in, they slough off. They can return but, will not always as the same receptor
What are the components that compose the olfactory epithelial?
Olfactory neurons- (25 million, unmyelinated, bipolar )
Sustentacular cells
Basal cells
Which cell in the olfactory epithelium helps with metabolic functions of the olfactory neurons?
Sustentacular cells
Which cells of the olfactory epithelium are the cells that replace the eroded cells?
Basal cells
There are 25 million olfactory neurons in the olfactory epithelium, how are the classified?
Bipolar unmeylinated
Where do the estimated 25 million olfactory neurons travel?
Through 15 holes in the cribriform plate, becoming the olfactory nerves.
(They don’t travel far)
T/F: Mature olfactory have no nucleus
True
Supporting cells do
Why do olfactory neurons have cilia?
Cilia increases the surfaces areas for more receptors
What is the function of the sustentacular cells?
Process ions and other substances
Damage to the upper layer of the olfactory epithelium results in?
Cells will be replaced by basal cells
Damage to the lower layer of olfactory epithelium results in?
Reproduction of cells will not occur because basal cells will be destroyed
Once the fibers of the olfactory neurons cross the cribriform plate where do they enter?
Olfactory bulb
What are the cells in the olfactory bulb?
Mitral cells/Tufted
Glomeruli
Periglomerular cells
Granule cells
Cells in the olfactory bulb that are considered the output cells?
Mitral & tufted
Which cells in the olfactory bulb axons make up the olfactory tract?
Mitral & Tufted
They leave the bulb
Which cells in the olfactory bulb is a knot of fibers that is an area of synapse?
Glomeruli
Which cells in the olfactory bulb are interneurons that surround the glomeruli?
Periglomerular cells
Which cells in the olfactory bulb are interneurons that are closer to the olfactory tract?
Granule cells
Which cells of the olfactory bulb reach into the glomeruli to synapse with the incoming olfactory nerve from fibers that passed through the cribriform plate?
Mitral
Tufted
Periglomerular
Olfactory receptor/ Triad:
The olfactory neuron/receptor cell (Excites/inhibits) mitral cells and this path has (one/two) synapse in glomeruli, then goes to the brain.
Excites
One
Excitation of (mitral/periglomerular) cells is the fastest path to the brain?
Mitral
Olfactory receptor/neurons (excites/inhibit) periglomerular cells.
The periglomerular are (inhibitory/excitatory) and they will shut off_________ cells.
The ______ cells then (excites/inhibits) the Periglomerular cells
Excites
Inhibitory
Mitral
Mitral
Excites
(Mitral cells excitation of the inhitory periglomerular cells allow for stimulus to go unnoticed after a while (i.e. Cologne)
The feedback loop of the periglomerular cell to mitral cell then back?
Negative feedback
Which pathway of the olfactory triad is the fastest to the brain?
Olfactory neuron —> Mitral cell
Mitral cell excitation path to brain?
Olfactory receptor —> + Mitral cell —> olfactory tract —> either to recurrent collateral that turns on granule cell that turns off mitral cell. Or to lateral stria
What are the stria that the olfactory tract splits into ?
Medial stria
Lateral stria
Intermediate stria
The olfactory tract splits into this stria, goes to contralateral bulb via anterior commissure, then inhibits contralateral mitral cells indirectly by exciting the granule cells.
Medial Stria
*tells direction of odor
Olfactory tract splits into this stria that goes to the piriform lobe, an area in the temporal lobe (inferior/anterior including uncus & parahippocampal area)
Lateral stria
AKA for piriform lobe?
Olfactory cortex
EntoRhinal cortex
The piriform lobe is associated with which system?
Limbic
*connects smells to memory/emotion
The olfactory tract splits into this stria that goes to mediodorsal nucleus of the thalamus, then to the orbitofrontal cortex.
Intermediate stria
Which stria ends up in the orbitofrontal cortex that allows for identification of what is being smelled?
Intermediate stria
If on the test as an answer choice, which sensory system does not go to the thalamus?
Olfactory
in actuality it does, just answer Mayne’s questions
Which stria helps determine direction of smell?
Medial
Which stria connects memory/emotion to smell?
Lateral
Which stria is responsible for perception, allowing identification of smell??
Intermediate
