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26 Cards in this Set
- Front
- Back
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A neuron in the retina would be what kind of cell type?
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bipolar
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What is the difference between active and passive properties of membranes?
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active: an electric current causes the membrane to reach a threshold which causes rapid and active depolarization takes place
passive:The cell membrane potential follows the the same direction as the current stimulated the cell |
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The ability to measure changes in the membrane potential is ______.
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electrophysiology
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Why is passive signaling not useful for conveying information?
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It dissipates over a distance so it isn't good for long distance communication
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What is the intra and extracellular conc. of K+? of Na+?
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K+: intra=140mM extra=5mM
Na+: intra= 5-15mM extra=145mM |
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How are differences in the concentration of Na+ and K+ maintained in the cell?
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active transporters and ion channels
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Why does a resting membrane have a negative charge?
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Leaky K+ channels (2-pore K+ channels) leak K+ out into the ECM while other ion channels are closed
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What is the intra and extracellular conc of Ca++? Cl-?
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Ca++ intra=0.0001mM extra=2mM
Cl- intra= 4-30 extra= 110 |
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What causes the equilibrium potential in our cells?
How does this relate to the Nernst equation? Goldman's equation? |
Electrochemical equilibrium is causes by Leaky K+ channels makes the membrane negative which balances with the repulsion force created by the K+ on the outside
Nernst equation finds out the membrane potential due to one type of ion moving in or out of the cell = constants x (ions in ECM/ion in cell) Goldmans takes into account all the ions moving in and out of a cell (same as Ernst equation but add in ratios of Cl-, Ca++, Na+, K+ |
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At rest, what is the ratio of k+, Na+, Cl- inside of a cell?
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1: 0.04: 0.45
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What ion has the highest permeability in a neuron?
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K+
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For neurons, What defines the:
overshoot? spike height? duration? threshold? refractory period? |
overshoot: how much higher than a 0mV membrane
spike height: difference between the peak of AP and the lowest value of the after hyperpolarization duration= how long the AP lasts, width measure at 1/2 the height threshold=the voltage of the membrane required to have an AP refractory period= the absolute refactory no other APs can be generated but the relative refractory can generate APs still |
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Since APs are all or nothing and have the same amplitude, how are messages carried out?
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frequency of message
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What are the different types of K+ channels?Which is responsible for leakiness?
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Kv and Herg= voltaged gated
inward rectifier Ca++-activated 2-P=leaky channel |
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If I ate a puffer fish not properly prepared and ingested tetrodotoxin, what would cause my death?
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Na+ voltage channels would be blocked so no APs could be generated so paralysis would cause death
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If I was eating oysters from a bay infested with red tide which poisoned the oysters with saxitoxin, what would cause my death?
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Na+ voltage channels would be blocks so no APs could occur which causes paralysis and death
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If I was bitten by a snake that sequestered dendrotoxins, would would occur?
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My K+ voltage gated channels would be blocked
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What are the effects of taking procaine, lidocaine, bupivacaine?
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Blocks Na+ channels
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What characteristic does an axon have when it has a short length constant?
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Membranes have lower membrane resistance so are leakier so the signal can't propagate far
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What does the length constant measure?
What properties effect the length constant of an axon? How can you get the largest length constant and why is that important? |
1. resistance of plasma membrane
2. resistance of intracellular fluid 3. resistance of extracellular fluid It measures the distance of a signal passively traveling away from the source To get a high length constant, you want a very high membrane resistance and a very low intra and extracellular fluid resistance |
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What does the time constant measure?
What properties effect the time constant? |
Tau=Time constant measures how long it takes to rise or fall 63% from the maximum voltage value
Size of neuron: 1) large cells have lower resistance and higher capacitance (takes longer to reach max volt.) |
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When an axon is unmyelinated, how do the APs propagate?
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A stimulus causes Na+ channels to open and depolarization to occur. Current that passively more down causes more channels to open. Na gates that first opened now close because K+ channels open to cause hyperpolarization
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What is the part of the neuron where there is a high density of Na+ channels?
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axon initial segment=where AP start
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What dictates the direction of APs and what are variations of the APs direction?
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refractory period dictates AP direction but APs can move backwards (back-propagating APs) to tell the dendrites how active the neuron is to effect the spike-timing dependent plasticity
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If you increase the diameter of an axon, what does this do to the signal?
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increases conduction so the signal can travel farther
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How does myelination effect conductance and signaling?
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Enhances conduction so it enhances the speed of the signal
Na+ gates are located in the Nodes of Ranvier where there isn't myelination so signal "jumps" |
