DSA Neuroanat. Of Gustation And Olfaction Flashcards
What makes olfactory receptor neurons very sensitive?
Thin nasal bones
What do olfactory receptor neurons recognize?
Allows for role in what?
Recognize 1000s of airborne odors
Role in pleasure assoc. w/ eating and in recognizing environments
What are the 4 basic tastes?
Fifth?
Sweet
Salty
Sour
Bitter
Umami
What recognizes a wider variety of sensations?
Nose or tongue?
Nose
What is the sensation of Umami important for?
ID of Amino Acids
How do we perceive different tastes?
Different combos of taste receptors
How does smell get transmitted to brain?
Smell —> filtered thru nostrils —> back of nose —> Olfactory epithelium —> olfactory receptor cells —> olfactory tract —> brain
What is unique about the olfactory epithelium?
Pigmented and we don’t know why
What is the only neuron that gets replaced regularly?
Olfactory receptor neurons
Where will the olfactory tracts make stops in the Brain?
Amygdala
Thalamus
Neocortex
What is the olfactory bulb for?
Where is it?
Helps humans smell
Lies in cribriform plate of ethmoid bone
What is the olfactory tract for?
Helps transmit sensory info from environment to the brain
Where is the cribriform plate?
Rostral end of olfactory sulcus and anterior cranial fossa
What helps keep the nasal cavity moist?
Ducts and gland of the olfactory epithelium
Where are the dendrites and receptors of the olfactory nerves?
Extended into the olfactory epithelium for good exposure to smell molecules
What are the layers of the olfactory epithelium, histologically?
Lamina propria Basal cells Olfactory receptor neurons Supporting/sustentacular cellls Brush cells Cilia Mucus
In the Olfactory Epithelium,
What is the lamina propria?
Role?
Layer of ct
Holds immune cells - important bc mucosa is directly exposed to external environment
In the Olfactory Epithelium,
What is the basal cell layer?
Role?
Cells next to basement membrane
Act as stem cells for ORNs and supporting cells
Will continuously turn over
Life span of 30-60 days
In the Olfactory Epithelium,
What is the Olfactory Receptor Neuron layer?
Role?
Cell bodies of nerve
Single dendrite will extend to mucus layer
Axons to olfactory bulb thru the lamina propria
In the Olfactory Epithelium,
What is the Supporting/Sustentacular Cell layer?
Role?
Cells that offer physical and metabolic support to surrounding cells
In the Olfactory Epithelium,
What are the brush cells?
Ciliated columnar epithelial cells
In the Olfactory Epithelium,
How would you describe the layer of cilia?
Non-motile
In the Olfactory Epithelium,
How is the mucus made?
Made and secreted by glands and ducts in OE
Where are olfactory receptor neurons located?
On roof of nasal cavity
Inferior surface of cribriform plate
Along nasal septum
On medial wall of superior turbinate
How many dendrites does CN1 have?
What does it do?
Where is its receptor?
Single dendritic process per neuron that receives info from environment
Receptor is in olfactory mucus of superior portion of nasal cavity
What is the purpose of the Cilia of Olfactory receptor Neurons?
Non-motile
Have odorant receptors (GPCRS-Golf) that will send signal to olfactory bulb
How is smell transmitted? (4 steps)
- Smell molecule —> mucus layer covering OE —> odorant binding proteins in mucus
- Binds GPCR (Golf) —> Adenyl cyclase —> increased cAMP
- Increased cAMP —> opens ion channels, allows influx of Na and Ca into cell
- Depolarization, AP —> neurons in Olfactory bulb
How is the olfactory epithelium organized?
In a receptor map, with different regions lining up and carrying info to specific areas of olfactory bulb
= initial step for olfactory discrimination
How are odors perceived?
Encoded by several different receptors are varying magnitudes
How does the Olfactory Epithelium make a Receptor map?
By preferentially distributed receptors int he olfactory epithelium
How many odor molecules can bind an olfacotry receptor neuron?
Only 1 type bc only 1 type of odorant receptor
What do the axons of the olfactory receptor neurons extend upwards thru?
In order to do what?
Cribriform plate (part of ethmoid bone) in order to synapse w/ the olfactory bulb
What are the 5 layers of the Olfactory bulb? (From olfactory tract to cribriform plate/OE)
(deep to superficial)
- Granule layer
- Mitral layer
- External Plexiform layer
- Glomerular Layer
- Olfactory Nerve Layer
“GRow My EGO”
How do centrifugal fibers reach the olfactory bulb?
What is their purpose?
Via anterior commissure
Help regulate feedback loops
What is the purpose of the olfactory tract?
Connects the bulb to the rest of the brain?
What are the components of the Olfactory tract?
Lateral olfactory tract
Cells of anterior olfactory nucleus
Fibers of anterior limb of anterior commissure