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36 Cards in this Set
- Front
- Back
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What structures in the cell membrane function as ion channels?
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Integral proteins
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Ion channels are selective ions? What three characteristics of the ions are important for this selectivity?
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1. charge
2. size 3. amount of water around ion. |
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Channels can be classified as either gated or nongated channels. A sodium channel that is always open would be classified as a ( ) channel.
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passive
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Voltage-gated potassium channels open at what voltage?
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130mV
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On what areas of the neurons are non-gated (passive) channels found?
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Dendrites, Axon, Cell Body (Soma)
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On what areas of the neurons are chemically-gated channels found?
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Dendrites, Cell Body
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On what areas of the neurons are Voltage-gated channels found?
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Axon
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What type of potential results from a Non-gated (passive) channel?
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Resting
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What type of potential results from a Chemically-gated channel?
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synaptic
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What type of potential results from a Voltage-gated channel?
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Action
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Excitable cell, like neurons, are more permeable to ( ) than to ( ).
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K+, Na+
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What acts as a chemical forct that pushes K+ out of the cell?
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concentration gradient
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What force tends to pull K+ back into the cell?
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electrical gradient
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When the concentration and electrical gradient are equal and opposite in a cell permeable only to K+, what is this called?
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equilibrium
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At the equilibrium potential for K+ what is the mV level?
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-90mV
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Does the concentration gradient (oppose/promote) the movement of Cl- into the cell?
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promote
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Does the electrical gradient (oppose/promote) the movement of Cl- into the cell?
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oppose
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What is the resting membrane potential?
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-70mV
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What compensates for the movement (leakage) of Na+ and K+ ions?
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Na+K+ pump
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The action potential changes the membrane potential from ( )mV resting to ( )mV and back again to the resting membrane potential.
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-70, +30
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Action potential results from a change in membrane permeability first to ( ) and then to ( ) due to the opening of what type of ion channels?
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Na+, K+, Voltage-gated
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Where is the density of voltage-gated Na+ channels the greatest?
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Axon Hillock
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What areas of the neuron generate signals that open these voltage-gated channels?
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Dendrites, Cell Body
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The opening of voltage-gated channels causes the membrane to?
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depolarize
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If the membrane reaches the trigger point, known as ( ) what electrical potential will be generated?
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threshold, action potential
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During the depolarization phase, voltage-gated ( ) channels open and ( ) enters the cell.
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Na+, Na+
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What are the two processes that stop the potential from rising above +30mV?
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1. inactivation of voltage-gated Na+ channels.
2. opening of voltage-gated K+ channels |
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The opening of voltage-gated K+ channels cause the membrane to?
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repolarize
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When voltage-gated K+ channels open does K+ move in or out of the cell?
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Out
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If the membrane potential becomes more negative than -70mV, what is this called?
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Hyperpolarization
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Hyperpolarization is caused by what characteristic of K+ permeability?
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slow decline
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After an action potential, the neuron cannot generate another action potential because ( ) channels are inactive. What is this period called?
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Na+, absolute refractory
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During the ( ) period, the cell can generate another action potential but only if the membrane is (more/less) depolarized?
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relative refractory, more
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Conduction velocity along the axon is increased by what two characteristics?
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1. increased diameter
2. presence of myelin |
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Conduction along a myelinated axon is called ( ) conduction.
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saltatory
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What does Multiple Sclerosis destroy? How does this stop action potential?
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Myelin sheaths of CNS axons. Too few voltage-gated Na+ channels between Nodes of Ranvier.
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