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26 Cards in this Set

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  • Back
What is the term for a sense that can sense something at a distance?
What are three characteristics for chemicals that we can smell?
1.volatile (vaporize easily)
2. Must be soluble in both water and lipids.
3. Usually organic
How many different odors can be discriminated?
about 10000
What is the basic outline of the olfactory sense?
1. Chemicals inhaled
2. Dissolved in olfactory epithelium (or mucosa)
3. Interact with receptors
4. Nerves go directly to olfactory bulb and brain.
What is the roughly bottom-to-top layout of mucusa and olfactory bulb?
mucous, cilia of receptors, nerve fibers, cribriform plate (porous bone), olfactory bulb
What are two things you can say about the receptor cells?
1. Lock and key binding based on compound shape.
2. Not specific: respond in different amounts to different chemicals.
What about organization of mucosa into zones?
1. Divided into 4 zones.
2. Different types of receptors in each zone, but a given receptor is only found in one zone.
3. Makes sense: heavier compounds fall sooner, also related to airflow.
How does the mucosal organization relate to the olfactory bulb organization?
1. Zones in mucosa correspond to zones of glomeruli.
2. Each different type of receptor ends up in only one or two glomeruli (bundle of synapses).
3. Many to one reduction.
What are the two types of olfactory cortices and where are they relatively located?
Primary olfactory cortex (piriform), back, secondary olfactory cortex (orbito-frontal) front
Is the olfactory pathway ipsi- or contralateral? What is another part of the brain that it connects to?
Ipsilateral (two olfactory bulbs on each side). Amygdala, related to emotions.
How is intensity coded?
More receptors receiving chemical, more intense smell (summation).
How is perceptual constancy in vision related to smell?
Vision: object is bigger, must be closer. Smell: object smells more intensely, must be closer.
How is the type of smell (quality) encoded?
Through a pattern of activity across a range of regions in the mucosa.
What can you say about similar chemical structure and perception?
Sometimes, chemcals are very similar in structure yet result in different perceptions. Sometimes, chemicals very different in structure but result in same perception.
How is the smell threshold similar to ideal auditory and visual thresholds?
We can perceive one molecule of mercaptan in a large number of molecules in air. Similar to perceiving one photon or tiniest vibration in air.
What can you say about gender, age, and adaptation?
Gender differences in smell perception, smell declines with age, adapt to prolonged stimulus.
What did the experiment with episodic vs. laboratory odor find out?
If people have a story or shock associated with odor, much more likely to remember it. Odor can serve as a very potent and long-lasting memory cue.
What do releaser pheromones do?
Produce an immediate and direct effect on the receive. E.g. female dog releaser hormone causes male dog to intiate mating behavior.
What do primer pheromones do?
Produce a long-lasting receptive state or physiological change (usually hormonal.
What do marker pheromones do?
Used by some mammals to mark their territories by leaving chemical trails.
Alarm pheromones
Pheromones that signal the presence of danger.
What about pheromones in humans?
Possible, but not confirmed. Women may synchronize their mentrual cycles via transmission of pheromones...evoluitionarily, regular mentrual cycles could increase chances of succesful conception.
What is the common chemical sense?
A system that serves as an irritant detector: stimulated by chemical irritants touching mucosal surfaces.
What types of receptor cells are most likely used in the common chemical sense?
Free nerve endings with simple binders.
Where in the brain do taste and smell combine in flavor perception?
The orbital-frontal cortex.
What is the perception of taste also influenced by?
The limbic system (emotion, hunger).