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WorksheetsPHY 2011 Nerves
Total questions: 15
Worksheet time: 8mins
The Goldman Hodgkin Katz equation
Is used to predict the peak of the AP
Is able to predict the trough of the AP
Is used to predict the equilibrium potential for Na+
Is able to predict the nerve resting membrane potential
Is used to predict the equilibrium potential for K+
The equilibrium potential is
Another term for the resting membrane potential for a non-penetrating ion
A shorthand version of the GHK equation for a permeating ion
The membrane potential that balances off the concentration gradient for a permeating ion
The membrane potential that balances off the concentration gradient for a non-penetrating ion
The membrane potential that balances off the concentration gradient for a uncharged molecule
The Nernst equation
Predicts the equilibrium potential for a permeating ion
Predicts the resting membrane potential for a permeating ion
Predicts the peak of the AP for a permeating ion
Predicts the resting membrane potential if more than one ion permeates the cell
Predicts the resting membrane potential if you have large protein molecules inside the cell
At the peak the AP does not reach the equilibrium potential for Na+ because
The concentration gradient for Na+ is lower due to Na+ influx
The concentration gradient for K+ is high compared to that for Na+ due to Na+ influx
Voltage-gated Na+ channels become refractory
Voltage-gated K+ channels become refractory
The membrane potential becomes +30 mV
At the end of the repolarization phase of the AP, the membrane potential becomes about -85 mV because
That is the equilibrium potential for K+ which is the only permeating ion at that stage
That is the equilibrium potential for Na+ which therefore cannot permeate at that stage
That is the equilibrium potential for the Na+/K+ pump
That is what is predicted by the Goldman-Hodgkin-Katz equation
That is when voltage-gated K+ channels become refractory
Differences in potential across a membrane arise because
Neural membranes are selectively permeable to molecules with a particular charge
Neural membranes are selectively permeable to charged molecules with a particular lipid solubility
Neural membranes are selectively permeable to charged molecules with a particular size
Neural membranes are selectively permeable to charged molecules with a particular concentration gradient
Neural membranes are totally impermeable to charged molecules even with facilitated diffusion
The neural resting membrane potential is primarily due to
Large efflux of K+, a small influx of Na+ and membrane impermeability to large negatively charged proteins
A small efflux of K+, a large influx of Na+ and membrane impermeability to Cl-
A large efflux of K+ and Cl- and membrane impermeability to Na+
Membrane impermeability to charged particles
The selective permeability of nerve membranes to uncharged proteins and ions
The passive flow of current along a neuron is called
Electrotonic flow
AP propagation
Saltatory conduction
Unsaltatory conduction
Selective permeability
Regeneration of current flow along a neuron is achieved by
Electrotonic flow
Production of APs further along
Saltatory conduction of current
Triggering the Na+/K+ ion pump
Use of chemical neurotransmitters
Production of APs along the length of a neuron
Slows down the conduction velocity
Slows down conduction velocity but only in unmyelinated neurons
Speeds up the conduction velocity
Speeds up conduction velocity only in myelinated neurons
Speeds up conduction velocity only in unmyelinated neurons
Threshold for an AP denotes
Threshold for opening of voltage-gated Na+ channels
Threshold for opening of voltage-gated K+ channels
Threshold for opening of chemically-gated Na+ channels
Threshold for activation of ATP to activate the Na+/ K+ pump
Threshold for return of the membrane potential to the resting level
Opening of voltage-gated K+ channels during an AP
Is a time-dependent phenomenon that occurs towards the end of the AP depolarization phase
Is a time-dependent phenomenon that occurs towards the end of the AP repolarization phase
Is a time-dependent phenomenon that occurs towards the end of the AP hyper-polarization phase
Occurs when the membrane potential reaches the equilibrium potential for Na+
Occurs when the membrane potential reaches the equilibrium potential for K+
The advantage of electrotonic current flow along an axon is that
It does not cause voltage-gated Na+ channels to become refractory
It does not cause the eflfux of K+ to cause the membrane potential to repolarize
It is fast and occurs at about 1/9 the speed of light
It allows neurons to integrate information
It allows neurons to synchronize different parts of their axon
Electrotonic current flow
Is needed to allow the axon hillock to integrate information
Will be faster in small-diameter neurons and large-diameter neurons
Will be at the same speed in small-diameter neurons and large-diameter neurons
Will be faster in large-diameter neurons than in small-diameter neurons
Allows for information to flow down large diameter neurons with no loss but leaks out in small diameter neurons
The purpose of myelination is to provide insulation to
Speed up electrotonic current flow along the axon
Decrease the need to produce APs to regenerate current flow
Increase the speed of producing APs at the nodes
Increase the speed of producing APs at the nodes
Decrease the leakage of APs at the nodes
