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24 Cards in this Set
- Front
- Back
Ion channels
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What controls the movement of ions across the membrane of a neuron?
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1. selective
2. passive or active 3. regionally located 4. functionally unique |
What are four properties of ion channels?
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Integral proteins
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What are ion channels made of?
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They select certain molecules to let in, and select some to keep out.
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What does it mean to say "Ion channels are selective"?
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1. charge of ion
2. size of ion 3. how much water theion attracts & holds around it. |
What three factors determine the selectivity of an ion channel?
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Active - have gates
Passive - are always open (leakage channels) & continuous ion movement |
What's the difference between an active and passive ion channel?
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outside
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Is a resting neuronal cell membrane more positive inside or outside?
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membrane potential ??
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What is the result of the charge separation in a resting neuronal membrane?
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closed
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When the neuronal membrane is at rest are the voltage-gated channels opened or closed?
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It causes the voltage-gated channels to open or close.
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What happens to the voltage-gated channels when there is a nerve impulse (or action potential) in the neuronal membrane?
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Because a + ion is moving inward, making the inside of the membrane more +.
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Why, when the Na+ voltage-gated channel opens, does the membrane potential goes from -70 mV to less negative values.
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Because the + ion is moving outward, making the inside of the membrane more -.
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Why, when the K+ voltage-gated channel opens, does the membrane potential goes from +30 mV to more negative values (-70).
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voltage - gated
chemically - gated |
Give two general types of active channels.
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neurotransmitters (ACH & GABA)
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What will open a chemically-gated ion channel in a neuron?
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No
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When a neurotransmitter opens a chemically-gated channel, does the neurotransmitter go into the cell?
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Na+ & K+
They move in both directions |
When GABA binds to its receptor, which ion(s) will move across the membrane? In which direction will they move?
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chloride ions
They move into the cell |
When acetyl choline binds to its receptor, which ion(s) will move across the membrane? In which direction will they move?
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The neurotransmitter that binds to the receptor
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What determines the direction that ions move through an ion channel?
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in the cell membrane, dendrites, cell body, and axon
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On what parts of the neuron do we find passive channels?
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dendrites and cells
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On what parts of the neuron do we find chemically-gated channels?
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Axon hillock
Unmyelinated axons nodes of Ranvier in myelinated axon. |
On what parts of the neuron do we find voltage-gated channels?
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Voltage-gated channels
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are responsible for the generation of the action potential (nerve impulses)- the outgoing signal from the neuron
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Chemically-gated channels
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are responsible for potentials generated at synapses (synaptic potentials)
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Passive channels
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are responsible for the resting membrane potential
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