2.ppt - Unit A 13.2 Electrochemical Impulse http\/www.youtube.com\/watch?v=pbg5E 9GCNVE http\/highered.mcgraw-hill.com\/sites\/007

2.ppt - Unit A 13.2 Electrochemical Impulse...

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Unit A
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13.2 13.2 Electrochemical Electrochemical Impulse Impulse 9GCNVE 2943696/student_view0/chapter8/animation_ _voltage-gated_channels_and_the_action_po tential__quiz_1_.html
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MEMBRANE POTENTIAL MEMBRANE POTENTIAL Is the potential difference (difference in electrical charge) in the voltage across a plasma membrane
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it is formed by the distribution of ions across the membrane. (movement of ions)
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it is -70mV when the neuron is at rest It is +40mV when the neurons is excited
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A. THE RESTING POTENTIAL A. THE RESTING POTENTIAL is the voltage when the neuron is at rest (not excited/ stimulated)
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there is a higher concentration of Na + outside the cell than inside
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K + ,Cl - and negative amino acids are inside the membrane
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It is a non- conducting situation The nerve cell is not being stimulated
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Na + channels are closed K + channels open K + moves outside the cell leaving fewer K + inside The negative ions and amino acids are trapped inside
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K+ K+ K+ K+ K+ K+ K+ K+ K+ Cl- Cl- Cl- Cl-
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To balance the excess positive ions outside the cell, negative ions (Cl - ) in the cell accumulate along the membrane edge
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The membrane is now said to be polarized The resting membrane has a potential difference of -70mV It means that it is 70mV more negative than the outside
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B. ACTION POTENTIAL B. ACTION POTENTIAL Are nerve impulses or signals that travel along the axon Occur at the nodes of myelinated neurons Occurs when a neuron depolarizes
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Cause inside the cell to become positive Occurs when threshold level is reached (a neuron is stimulated enough)
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It causes: Sodium gates to open An electrical impulse to sent down the axon
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The inside of the axon becomes more positive
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K + channels close Na + channels open
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Positively charged Na ions: rush into the cell , moving down their concentration gradient are attracted to the negative ions inside the cell
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  • Winter '17
  • John Travis
  • Schwann Cell

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