Editing 20110105 Lecture 4 notes.txt
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**Bitter is associated with toxins. | **Bitter is associated with toxins. | ||
**The mechanism is different for each "taste". | **The mechanism is different for each "taste". | ||
- | |||
*Salty comes from activity of epithelium sodium channels: | *Salty comes from activity of epithelium sodium channels: | ||
**Highly expressed in kidney, too, so we know lots about them. | **Highly expressed in kidney, too, so we know lots about them. | ||
- | *** | + | ***IMportant for na reabsorption and water retention. |
**Has three subunits. | **Has three subunits. | ||
- | **Protein is | + | **Protein is constinutively active: always open, allowing Na into the taste cell to cause depolarization. |
- | **Depolarization causes activation of voltage gated | + | **Depolarization causes activation of voltage gated cA channels, then AP, then release of serotonin in synaptic cleft of facial nerve. |
- | + | ||
*Bitter test | *Bitter test | ||
- | ** | + | **detects Acids |
- | + | **Protien senstivie channels | |
- | + | **mechanism is the same: Na permeability, Ca channels open, Ca influx, AP, release of serotonin | |
- | ** | + | |
- | + | ||
*Sweet and Umani and some bitter: | *Sweet and Umani and some bitter: | ||
- | **Occurs through T1 / T2 (for sweet), T1 / R3 (Umani), T2 (bitter) | + | **Occurs through T1 / T2 (for sweet), T1 / R3 (Umani), T2 (bitter). |
- | **These are g-protein | + | **These are through g-protein which activate Phosphorlipase C which cleaves PIP2 to form DAG and IP3. |
***IP3 causes IP3R on the ER to release Ca+. | ***IP3 causes IP3R on the ER to release Ca+. | ||
***DAG cuases opening of Ca+ channels on the outer membrane (TRPM5) to augment Ca influx. | ***DAG cuases opening of Ca+ channels on the outer membrane (TRPM5) to augment Ca influx. | ||
****This channel has similar structure to the others we've seen. | ****This channel has similar structure to the others we've seen. | ||
**Influx of Ca+ causes an AP. | **Influx of Ca+ causes an AP. | ||
- | + | *All these receptors are expressed on all receptors (we think) but it isn't totally clear the distribution and differentiation mechanisms. | |
- | *All these receptors are expressed on all receptors (we think) but it isn't totally clear the distribution and | + | *Type II taste cells don't express any voltage-gated Ca channels so they may not detect...? |
- | + | ||
===Hearing=== | ===Hearing=== |