Olfaction Flashcards
• Gate control theory of olfaction
is a theory of the processes of nociception. The gate control theory of pain asserts that non-painful input closes the “gates” to painful input, which prevents pain sensation from traveling to the central nervous system. Therefore, stimulation by non-noxious input is able to suppress pain. “Fast blocks slow”
accessory olfactory epithelium/ bulb
Specialized part of olfactory epithelium in animals .It sends projections to the accessory olfactory bulb which then sends signals to the brain.
- humans dont have accessory olfactory bulb as we rely little on pheromone signals
vomeronasal system.
Within the accessory olfactory epithelium, you have a structure called the vomeronasal system.
In vomeronasal system, there are basal cells and apical cells. They have receptors at tips.
basal cells on the vomeronasal system
Basal cell sends axon through accessory olfactory bulb to glomerulus, then mitral or tufted cell which eventually goes the limbic system (amygdala, hippocampus, hypothalamus)
• How does a molecule bind to an olfactory receptor and cause an AP
The molecule binds to the GPCR receptor on odor molecule -> GPCR on olfactory epithelia -> G-protein dissociates and causes a cascade of events inside the cell -> G protein binds to ion channel which allows + ions outside the cell to come inside -> opens and triggers an AP -> goes to cribriform plate -> glomerulus -> activate mitral/tufted cell -> synapse to brain (primary olfactory cortex in temporal lobe)
The labeled-line theory of olfaction
describes a scenario where each receptor would respond to specific stimuli and is directly linked to the brain.
The vibrational theory
of olfaction asserts that the vibrational frequency of a molecule gives that molecule its specific odor profile.
Steric theory of olfaction, or shape theory,
asserts that odors fit into receptors similar to a lock-and-key.
Anosmia
inability to perceive ordor/smell
