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→The ECG represents the sum of the action potentials of millions of cardiomyocytes
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==The ECG represents the sum of the action potentials of millions of cardiomyocytes== | ==The ECG represents the sum of the action potentials of millions of cardiomyocytes== | ||
[[ | The individual [[action potential|action potentials]] of the individual cardiomyocytes are averaged. The final result which is shown on the ECG is actually the average of billions of microscopic electronical signals. | ||
During the depolarization sodium-ions stream inwards the cell. Subsequently the calcium-ions stream into the cell. These calcium-ions give the actual muscular contraction. Finally the potassium-ions stream out of the cell. During the repolarisation the ion concentration is corrected. On the ECG, an action potential wave coming towards the electrode is shown as a positive (upwards) signal. Here the ECG electrode is represented as an eye. | |||
[[Image:Ion_currents_en.png|thumb|left|300px|Ion currents of the cardiomyocytes]] | |||
[[Image:Hart_cells_en.png|thumb|right|300px|The heart consists of approximately 300 trillion cells]] | |||
[[Image:cells_in_rest_en.png|thumb|right|300px|In rest the heart cells are negatively charged. Through the depolarization by surrounding cells they become positively charged and they contract.]] | |||
{| class="wikitable" align="center" width=385px font-size="70%" | {| class="wikitable" align="center" width=385px font-size="70%" | ||
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|<flashow>http://nl.ecgpedia.org/images/5/50/Single_cardiomyocyte.swf|height=350px|width=400px</flashow> | |<flashow>http://nl.ecgpedia.org/images/5/50/Single_cardiomyocyte.swf|height=350px|width=400px</flashow> | ||
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| This movie shows the contraction of a single (rabbit) heart cell. The glass electrode measures the electrical current in the heart cell (with the[[w:Patch_clamp|patch-clamp method]]). The electrical signal is written in blue and shows the actionpotential. ''Courtesy of Arie Verkerk and Antoni van Ginneken, AMC, Amsterdam, The Netherlands''. | | <small>This movie shows the contraction of a single (rabbit) heart cell. The glass electrode measures the electrical current in the heart cell (with the[[w:Patch_clamp|patch-clamp method]]). The electrical signal is written in blue and shows the actionpotential. ''Courtesy of Arie Verkerk and Antoni van Ginneken, AMC, Amsterdam, The Netherlands''.</small> | ||
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