Hearing, Smell, Taste- Smell Flashcards
How many odorants can humans discriminate?
- over 1 trillion!
Any 2 people differ in their expression of different odor receptors by…
30%
Where are rats’ olfactory bulbs located vs. humans’?
- rats’ are on the outside of the brain separately
- humans’ are on the inside of their brain
Where are odorants brought to after inhalation?
to the olfactory epithelium
What types of cells are found in the olfactory epithelium?
- Olfactory receptor cells (6 million
- supporting cells
- basal cells
What are olfactory neurons regenerated from?
basal cells- ex. of adult neurogenesis
Olfactory neurons structure (what do olfactory neurons have??)
- dendrite to olfactory mucosa with cilia extending from the dendritic knob
- unmyelinated axon to olfactory bulb
- metabotropic receptors on cilia and knob
How many types of olfactory receptors do each olfatory neuron express?
- only one
- each receptor belongs to 1 of 4 subfamilies
How many different olfactory receptors are there? How many are functional?
- 1000 different olfactory receptors
- Only 400 receptors are functional
Olfactory receptor signaling
Transduction (pt. 1)
- odorant binds to metabotropic receptor
- G-protein activated
- Adenylyl cyclase is activated and makes cAMP (2nd messenger)
Where does functional localization of olfactory receptors occur?
in epithelium
Olfactory receptor signaling
Transduction (pt. 2)
- cAMP causes cation (Ca2+, Na+) channels to open
- Voltage gated Cl- channels open to further depolarize cell (push out Cl-)
- action potential
Olfactory bulb
Where do olfactory neuron axons synapse?
- on mitral cells in the olfactory bulb
Where are mitral cells located?
- clustered into glomeruli (spheres of cells) in the olfactory bulb
What are glomeruli?
- spheres of mitral cells in the olfactory bulb
- A glomerulus receives input from olfactory neurons with same receptor type (separated by function in the olfactory bulb)
How are glomerus separated?
by function (in olfactory bulb)
piriform cortex
segregation of olfactory representation continues via thalamus into the cerebral cortex
Which brain areas relate smell to the brain?
- the hippocampus and amygdala
