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16 Cards in this Set
- Front
- Back
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The human brain alone contains
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One hundred billion nerve cells call Neurons
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A neuron, like every other cell, has:
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Positively and negatively charge ions inside and outside
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A resting neuron has: 1. A greater negative charge............ 2. A greater positive charge............. |
1. On the inside surface of the plasma Membrane 2. On the outside surface. |
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This partitioning of charge creates a voltage difference across the membrane known as |
The resting membrane potential, which can be measured used a voltmeter.
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On average, an intracellular electrode records a value of |
Minus seventy millivolts. (-70 millivolts)
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The resting membrane potential depends on two factors. FACTOR #1 |
The presence of sodium and potassium gradients across the plasma membrane.
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1. There are more sodium ions ....... 2. and more potassium ions ............ |
1. Outside the neuron than inside 2. Inside the neuron than outside. |
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The resting membrane potential depends on the differential permeability of the plasma membrane to sodium and potassium ions.
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Leak channels in the plasma membrane allows |
Sodium and potassium ions diffuse, or leak, down their concentration.
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The membrane contains many potassium leak channels than:
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Sodium leak channels.
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The membrane is much more permeable, or leaky, to :
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Potassium ions.
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As positively charged potassium ions leak out of the neuron the inside surface of the membrane becomes
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Negatively charged compared to the outside surface
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If potassium was the only ion moving, |
The potential would stabilize a minus ninety millivolts. (-90 millivolts)
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However, positively charged sodium ions leak into the neuron, which slightly ..... |
offsets the negative charge and raises the voltmeter reading to minus seventy millivolts. (-70 millivolts)
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Sodium-potassium pumps actively transport 1. Sodium ions 2. And potassium ions |
1. Out of the neuron 2. Back in, compensating for the sodium and potassium leaks. |
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The pumps help to |
Maintain the resting membrane potential.
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