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29 Cards in this Set
- Front
- Back
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About how often are olfactory neurons replaced? |
About every 28 days |
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How accurate is olfactory recall (memory of smells)? |
Olfaction is the most accurate sense with 65% accuracy in recall after a year. Sight, for comparison has roughly 50% accuracy after only 3 months. |
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Describe how easily the sense of smell adapts to stimuli. |
If you walk into a flower shop or bakery, you will no longer smell the pungent odors by the time you reach the checkout stand. |
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Describe Claus Wedekind's work. (Bonus: where did he do this work?) |
Claus allowed female participants to smell the shirts of several males and rate which shirt they felt smelled "most attractive". The females consistently picked the male with an immune system *the most different from their own*. This was at the University of Bern. |
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Name another observed effect of olfactory cues, aside from scent itself. |
Sweat of fearful men triggers women to interpret ambiguous facial expressions as fearful. Appraisal of unambiguous facial expression remains unchanged. |
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Name 3 unique features of the olfactory system. |
1. It projects ipsilaterally. 2. It does not immediately project to the thalamus. 3. The Pyriform cortex has 3 layers, not 6. |
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What is the order of neural connections in the olfactory system? (start with Olfactory receptors) |
Olfactory receptors > (olfactory nerve) > Olfactory bulb > (Olfactory tract) > Pyriform cortex, Olfactory tubercle, amygdala, entorhinal cortex > Orbitofrontal cortex, Thalamus, Hypothalamus |
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What separates the nasal cavity from the brain? |
The Cribiform Plate |
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Roughly how many Olfactory Sensory Neurons are there in a human? |
10 million Olfactory sensory neurons |
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Define: Anosmia |
Loss of sense of smell |
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List the steps of Olfactory sensation. |
1. Olfactory molecule binds with receptor. 2. G protein (with beta and gamma subunits) 3. "G off" protein activates Adenyl cyclase 4. ATP --> cAMP 5. cAMP binds to Na/Ca channel 6 Na and Ca enter cell 7 Ca binds to Ca gated Cl channel 8. Cl leaves cell, depolarizing membrane 9. (Ca/Na exchange pump?) |
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What are the 3 mechanisms that cause olfactory adaptation? |
1. cAMP initiated adaptation mechanism 2. strong binding of odorant to cell 3. "burial" and recycling of receptors |
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How many olfactory receptors are coded in the human genome? How many are expressed? How many expressed in blood hounds? |
1000, 350, and 750, respectively. |
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Explain ensemble (a.k.a. 'population') coding in the olfactory sense. |
A particular Olfactory sensory neuron may be stimulated by more than one specific odorant. The combined, variable inputs from all the sensory neurons completes the coding for each smell. |
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What sort of 'olfactory map' exists? |
One with no chemotopic order, that is conserved between species. |
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Compare orthonasal olfaction with retronasal olfaction. |
Orthonasal olfaction: odorants enter nasal cavity through nares and then bind with olfactory sensory neurons. Retronasal olfaction: odorants enter nasal cavity through the oropharynx/nasal pharynx and bind with olfactory sensory neurons. |
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What thalamic nucleus receives neural projections from the tongue? |
the Ventral Posterial Medial nucleus (VPM) |
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Define ageusia. |
Loss of the sense of taste. Caused by damage to VPM of thalamus or damage to gustatory cortex. |
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What area of the brain holds the gustatory cortex? |
The insula. |
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Where are taste buds located? |
In trenches around papilla on the tongue AND there are a few on the roof of the mouth. |
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How many taste buds are around a papilla? How many are in the human mouth on average? |
from 1 to several hundred. Around 4000. |
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How many taste receptor cells are in each taste bud? |
from 50 - 150 in each taste bud. |
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Explain in some detail taste transduction. |
Tastants are sensed in the trenches around papillae by microvilli of gustatory sensory neurons. Afferents lead to the Solitary Nucleus of the brain stem, and then to the VPM of the thalamus. Then on to the Insula and frontal cortex, then Amygdala and Hypothalamus. |
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Which cranial nerve(s) carry input from gustation? |
Cranial Nerve VII: anterior 2/3rds of tongue. Cranial Nerve IX: posterior 1/3rd of tongue. Cranial Nerve X: 'taste buds (epiglottis)' |
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Describe the transduction of the taste of salt |
Salt ions spread into the trenches around papillae and enter the apical domain (microvilli) of the taste cells through ion channels. This leads directly to depolarization. Na channels open, releasing sodium extracellularly. K channels open allowing the influx of potassium. Calcium channels open allowing the influx of calcium. Calcium promotes the release of serotonin into a synapse with an afferent neuron. |
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Describe the transduction of the taste of acid (sour). |
Hydrogen ions spread into the trenches around papillae and enter the apical domain (microvilli) of the taste cells through ion channels. This leads directly to depolarization. Na channels open, releasing sodium extracellularly. K channels open allowing the influx of potassium. Calcium channels open allowing the influx of calcium. Calcium promotes the release of serotonin into a synapse with an afferent neuron. |
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Describe the transduction of the taste of sweetness. |
a |
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Describe the transduction of the taste of umami. |
a |
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Describe the transduction of the taste of bitterness. |
a |
