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)
