Excitatio1 - Excitation Recall that the plasma membranes of...

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Excitation Recall that the plasma membranes of cells are selectively permeable. Thus, they are able to keep specific ions at a high concentration inside the cell and other ions high outside the cell. This results in the plasma membranes of cells being polarized or electrically charged. When measured with an electrode, the inside surface of the cell membrane is negative with respect to the outside surface of the cell membrane. This is known as the membrane potential . At rest, the membrane potential (negative inside , positive outside) is due to a very high concentration of Na + outside of cell and a high concentration of K + inside. Also contributing to the negativity of the inside are several impermeant anions . The charge on the plasma membranes of a cell can change in response to stimulation. This is the principle of excitability. If ion channels open and allow ions to move across the membrane, this will change the membrane potential. If the stimulus causes the membrane potential to depolarize
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Excitatio1 - Excitation Recall that the plasma membranes of...

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