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36 Cards in this Set
- Front
- Back
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permeability
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refersto the number of channels open at a particular moment in time
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conductance
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depends on both the number of open channels and the concentration gradient for a given ion
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What is unique about the glial cell permeability?
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passive potassium permeability
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depolarization
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bioelectric potential is decreased
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What happens when the glial cell is hyperpolarized?
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the EF will be stronger causing the K+ to be kept inside of the cell
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What happens when the glial cell is depolarized?
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the EF will be weakened and the concentration gradient will drive K+ outside of the cell
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equilibrium potential is determined from what equation?
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nernst equation
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what is nernst equation
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E=(RT/ZF)*ln([K]0/[K]i)
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What is the equilibrium potential for glial cell?
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Ek= -61mV
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in a glial cell Ek is closely approximate to the resting membrane potential. What is the relationship betwen Vm and [K+]0?
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it's linear
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What is the neuronal membrane permeable to?
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K+, Na+ and Cl-
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What is the resting membrane potential for Na+?
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60 mV
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for Na+, what do the EF and concentration gradinet favor?
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they both favor Na+ entry into the cell
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progressive depolarization of Na+
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it weakens the EF until the EF= -concentration graidient
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equilibrium potential of sodium is what value?
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60 mV in mammalian spinal motor neurons
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Neuronal Vm is slightly ___-depolarized than glial Vm
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more
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What is the role of the Na/K ATPase?
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maintenance of the electrochemical gradients
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What are the subunits of the Na/K ATPase?
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alpha and beta
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What is the beta-subunit?
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glycoprotein with 3 glycosylation sites..
regulatory/modulatory role |
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Where are the intracellular Na+ and ATP binding sites?
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alpha subunit of Na/K ATPase
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What is the phosophorylation site of the alpha subunit of Na/K ATPase called?
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Asp376
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Where are the extracellular K+ and glycoside binding sites of the Na/K ATPase?
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alpha subunit
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What is the stoichiometry of the Na/K ATPase?
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3 sodium out and 2 potassium in
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What is the pump activity fo the Na/K ATPase?
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electrogenic, contributes to Vm, and consumes up toe 70% of available ATP
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oubain or digitalis bind where on the Na/K ATPase?
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extracellular binding sites of K+ of the alpha subunit as cardiac glycoside inhibitors
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How is chloride distributed across the plasma membrane?
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passively dictated by its electrochemical gradient
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What deos the concentration gradient and EF favor for Cl- movement?
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concentration gradient: favors entry
EF: favors extrusion |
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equilibrium potential
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net flux of ion is zero
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What is the value of Ecl?
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-70 mV
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Which ion most closely approximated the neuronal resting membrane potential?
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Chloride at -70 mV
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What equation do we use to find resting mebrane potential in a neuron?
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goldman equation
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what is the goldman equation dependent on?
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ion concentrations and permeabilities
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Why is Cl- different in goldman equation?
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It's an anion so it needs to be flipped
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When applying the goldman equation to the glial cell, what will happen?
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it's just nernst equation
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What is the relative permeability between K, Na, Cl?
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Pk>PCl>PNa
1>0.45>0.04 |
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What is significant of the seminal experiments Hodgkin and Katz?
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reinforce that the Goldman equation use in calculating the resting membrane potential
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