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35 Cards in this Set
- Front
- Back
what does opening ligand gated channels produce?
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this produces graded potentials
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what does opening of voltage gated channels produce?
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this produces action potentials
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what are some of the changes that can lead to the production of an electrical signal?
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a change in electrical field
chemical messenger stiumulus (sound, vibration) spontaneous change in potential from imbalances in the leak-pump cycle |
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what kind of potentials does stimulating mechanosensitive channels produce?
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this produces graded potentials
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what generates the resting membrane potential?
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this is generated by background channels. These spontaneously open in the absence of external stimuli
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what are the main characteristics of graded potentials?
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these are Small, Local changes
May be hyperpolarizing or Depolarizing vary in amplitude and duration magnitude of potential is related to the magnitude of the stimulus bi directional flow decremental conduction |
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What happens with mixed cation channels are opened? What type of change does this lead to?
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This is an excitatory synapse.
When this is opened by (ACH), small outward flux of K+, large influx of Na+ Leads to depolarization |
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What happens when K+ or Cl- channels are opened? what type of change does this lead to?
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this is an inhibitory synapse
K+ outflow, or Cl- Inflow, leads to hyperpolarization |
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What are some excitatory neurotransmitters? 3
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glutamate, aspartate, ACH
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what are some inhibitory neurotransmitters? 2
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glycine, GABA
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what determines which direction a current flow is moving?
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this is determined by the direction the positive charges are flowing
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what are 4 examples of graded potentials?
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post synaptic portentials
end plate potentials pacemaker potentials slow wave potentials |
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what is temporal summation?
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summation of several ESPS from in SINGLE presynaptic neuron, only adjusts the time interval between firings
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what is spatial summation?
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summation of several ESPS from Different Presynaptic inputs
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what zone of a neuron initiates action potentials?
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the axon hillock
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When are all voltage gated channels triggers for action potentials?
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these are all triggered at threshold, they just have different built in delays, which produces the given effects
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In sodium channels, what are the two gates, and what are their relative speeds?
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both are activated during threshold, there is a channel opening which is very rapid (Na+ influx), and the slow closing inactivation gate
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What is the speed and flow of potassium channels in action potentials?
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these are also activated at threshold, but are slow opening. When they open, K+ rushes out
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what type of potential activates an action potential?
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this is activated by a large graded depolarization reaching the axon hillock (10-15mv)
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What is the first channel opened during an action potential? What does it cause?
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at threshold, sodium channels open first, leading to a rush of Na+ into the cell, depolarizing cell (rising phase)
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after Na+ rushes into a cell during depolarization, what happens?
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At the peak of the action potential, the Na+ slow moving inactivation gate closes, ending Na+'s rush in.
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Once Na+ stops going into the cell during an action potential, what happens next?
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Now K+ channels have opened up, causing K+ to leave the cell (escaping the positive charge) generates the falling phase.
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After an action potential has fired, what restores the original concentration gradients of Na+ and K+?
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this is done buy the Na+/K+ pump pushing K+ back into cell, and Na+ out of the cell
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What does Tetrodotoxin and Topical lidocaine do?
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these both inhibit voltage gated Na+ channels
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what is the purpose of the refractory period?
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this ensures one way propagation of action potentials.
limits frequency of potentials |
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what causes the absolute refractory period?
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this is caused by most voltage gated Na+ channels being inactivated, NO stimulus can elicit an action potential
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what causes the relative refractory period?
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this is causes by residual inactivation of voltage gated Na+ channels.
action potentials CAN occur here, but require a supranormal stimulus |
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What does Primary Hyperkalemic Paralysis do to skeletal muscles?
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this causes hyperexcitability of skeletal muscles, leading to spontaneous action potentials.
Leads to accomodation by Na+ channels and paralysis due to channel inactivation. |
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why does a hyperkalemic state raise the resting potential closer to threshold?
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this in essence reduces the drive between ICF and ECF K+'s concentration gradient. So with K+ have less of a say in the resting membrane potential....it will shift MORE towards Na+'s potential (+30, so depolarizing)
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Why does accommodation cause paralysis?
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Continuous depolarization allows some the voltage gated Na+ channels to inactivate, so even when the membrane is depolarized, not enough Na+ channels are available to initiate an action potential
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what does a the time constant mean?
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this shows how fast a cell can depolarize. a small time constant means fast depolariziation
t=Rm X Cm (time constant= membrane resistance times capacitance) |
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what is the length constant?
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this is how far a depolarizing current will spread along the membrane. A larger length constant the further the current will spread along the membrane
Determined by the root of membrane resistance over internal resistance |
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what is contiguous conduction?
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this is the conduction found in unmyelinated fibers, action potentials spread along the whole membrane. Slow
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what is saltatory conduction?
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this is rapid conduction in myelinated fibers. Impulse jumps over sections of myelination
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why is saltatory conduction faster?
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because the action potential does not have to be regenerated at myelinated sections.
up to 50x faster |