test 2 lec 2 part 1 Flashcards
depolarization part 2
Two major types of Voltage- dependent Ca2+ channel based on their kinetics?
LVA, HVA
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LVA VDCCS
Rapidly inactivating, low-voltage activate _ activate by a small amount of depolarization
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T-channels
they are LVA channel that produce a transient current
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_ HVA (high-voltage activated)
activate by a large amount of depolarization. There are 2 categories based on their inactivation:
1- Inactivating
2-Non-inactivating (or more slowly inactivating)
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single Vs whole cell current
single cell recording is a single ion channel under the electrode tip
Whole cell recording is the current of something approximating the entire cell
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which way is Ca2+ current
inward or downward deflection
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when does LVA channels turn on and off?
Turned on right around resting potential and peak current flow occurs at well below zero (hit their peak at negative potential.), then starts to turn off as action potential becomes stronger and moves past the 0 potential
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when does HVA channels turn on and off?
o Takes more depolarization to turn on, and won_t reach its max until somewhere well above zero.
o Right where the downslope of the LVA ends, the HVA peaks
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in I/V graph which way is the graph shifted by turning on HVA channels?
Rightward shifted on I/V curve.
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IV curves
it is a current/voltage curves, it shows the relationship of the curent vs voltage of a cell, Voltage is on the x-axis
o We can find resting potential and 0 potential and positive potential in unit of Voltage (V)
_ Hyperpolarize moves to the left
_ Depolarize moves to the right
o Current is on the Y-axis (measure of current in unit of Amp)
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what is the name of non-inactivation HVA channel?
o L-type channels
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o L-type channels
found in Cardiac and neuronal tissue, _ Non-inactivating: takes a lot of depolarization to turns on, and as long as cell remains depolarized, it stays activated, can be blocked by cadmium and can be restored to its original condition by washing out the blocker
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what are some of the slow-inactivation HVA channels:
o N-type channel, o P-type channels, o Q-type channels, o R-type channels
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o N-type channels
_ Slow-inactivating (SI)
_ Very common in neurons
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o P-type channels
_ Pre-synaptic & post-synaptic axon terminals
_ Slow-inactivating