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24 Cards in this Set

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