Term
| Which of the taste senses work via ion channels? |
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Definition
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Term
| Which of the taste senses work via G coupled protein receptors? |
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Definition
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Term
| What compounds confer the umami taste to food? |
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Definition
| Glutamate (MSG) and ribonucleotides |
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Term
| What 2 parts of the nose are olfaction receptors located on? |
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Definition
| Upper septum and turbinates |
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Term
| Which senses receptors are unique in that they are continuously renewed throughout life? |
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Definition
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Term
| Which factor determines specificity for olfactory receptors and what protein does binding of ligands to receptors stimulate? |
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Definition
1. Shape. Each receptor is a trans membrane protein with specificity for odor compound shape.
2. When bound, the receptor-ligand complex activates G proteins |
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Term
| Explain how a finite number of odor receptors leads to significantly more types of odor distinction |
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Definition
Different oderants are detected by different combinations of receptors, not just one specific receptor
This allows the receptor binding to be read like a code (similar to histone code) that determines odor description |
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Term
| Describe the path of the olfactory nerve |
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Definition
| It travels directly to the olfactory bulb and then to limbic system and also directly through the thalmus to the cerebral cortex. Does NOT travel through the brain stem. |
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Term
| What is the role of the external ear? |
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Definition
| To gather and funnel sound waves into the ear canal toward the tympanic membrane |
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Term
| What is the role of the middle ear? |
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Definition
| To overcome the impedance boundary of the air/water boundary and pass the pressure signal to the inner ear (done via ossicles and tympanic membrane) |
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Term
| What is the role of the inner ear? |
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Definition
| Transduce signal from middle ear to an electrical signal and pass this signal to the brain |
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Term
| Name and describe the 2 mechanisms of hearing loss |
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Definition
1. Conductive - sound not conducted to inner ear (outer, middle ear problems)
2. Sensorineural - Sound not converted to nerve pulses (inner ear is completely fucked) |
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Term
| Describe two ways by which sound localization occurs in the external ear |
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Definition
1. Difference in processing time between right and left ears yields horizontal position information
2. The way the sound waves bounce around the pinna in the outer ear yields vertical position information |
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Term
| What anatomical structure is responsible for replenishing/altering the middle ear air supply and what does it connect to in order to do this? |
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Definition
Eustachian tube
Connects to nose (yawn response to pop ears) |
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Term
| What are the 3 middle ear bones that help conduct air waves into water? |
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Definition
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Term
| What 2 features of the middle ear help it overcome the impedance of the air/water boundary? |
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Definition
1. Area ratio of tympanic membrane vs. stapes
2. Lever ratio of malleus vs. incus |
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Term
| What is otosclerosis and what is its treatment?? |
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Definition
1. Overgrowth of bone at the footplate of the stapes
2. Replace stapes with implant |
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Term
| What are the 3 fluid filled layers of the cochlea and what 2 membranes define them? |
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Definition
1. Scala vestibuli, Scala tympani, and sala media
2. Reissner's membrane and basilar membrane |
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Term
| Which of the 3 chochlear channels are the hair cells located in |
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Definition
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Term
| Explain the transduction mechanism of pressure waves to neural signal. |
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Definition
1. Pressure waves in scala vestibuli cross the scale media and enter the scala typani
2. As this happens, a traveling wave moves from the base to the apex of the basilar membrane
3. As the bailar membrane moves up, the tectorial membrane causes the hairs on the cells to deflect outward, increasing firing rate of nerve cells by opening of K channels (K flows inward) |
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Term
| What structure actively pumps K into the endolymph to maintain concentration gradient? |
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Definition
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Term
| Mutations in what structure account for 50% of congenital hearing loss births? |
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Definition
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Term
| Describe how frequency sensitivity varies along the cochlea |
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Definition
| As you travel up the cochlea it becoems both wider and looser, leading to different resonant frequencies along the length of it |
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Term
| What is the main consequence of OHC loss? |
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Definition
| A decrease in sensitivity to certain sound frequencies. Typically starts in the high frequency range and works downward. |
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Term
| Which hair cells tend do act as an amplifier and how does it accomplish this? |
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Definition
1. Outer hair cells
2. A voltage sensitive protein (prestin) amplifies vibration in the basilar membrane, and ultimatley the deflection of inner hair cell stereocilia |
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Term
| What is the name of the upper membrane that the stereocilia are bound to? |
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Definition
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Term
| What does tonotopically organized mean? |
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Definition
| Low frequency nerve endings are in the middle of the cochlear nerve and frequency increases as you move outward |
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Term
| What role does the cortex play in auditory functions? |
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Definition
| Speech perception, melody recognition |
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Term
| What is the role of the inferior colliculus in auditory function? |
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Definition
combine horizontal and vertical sound localization information
enhance amplitude |
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Term
| what is the role of the dorsal cochlear nucleus in auditory function? |
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Definition
| vertical sound localization |
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Term
| what is the role of the ventral cochlear nucleus in auditory function? |
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Definition
Extend sound level
Enhance contrast
Transmit to IC and SON |
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Term
| what is the role of the superior olivary nucleus in auditory function |
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Definition
| Horizontal sound localization |
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