AHCDW7SOL97.pdf - 97 Award 1.00 point Problems Adjust...

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Unformatted text preview: 97. Award: 1.00 point Problems? Adjust credit for all students. Click and drag the terms on the left to accurately complete the sentences on the right. Then click and drag the sentences to arrange them in order to accurately describe the process. ECF ICF action potential depolarizes hyperpolarizes potassium ion repolarizes resting membrane potential sodium ions stimulated A muscle cell is stimulated by a neurotransmitter from a motor neuron. Ion channels open in the plasma membrane and sodium ions diffuse into the ICF. The membrane depolarizes, or becomes less negative. Sodium ion channels close, but potassium ion channels remain open, and loss of that ion repolarizes the membrane. The process just described is called a(n) action potential. Explanation: When a nerve or muscle cell is stimulated, ion channels in the plasma membrane open and Na+ instantly diffuses down its concentration gradient into the cell. These cations override the negative charges in the ICF, so the inside of the plasma membrane briefly becomes positive. This change is called depolarization of the membrane. Immediately, Na+ channels close and K+ channels open. K+ rushes out of the cell, partly because it is repelled by the positive sodium charge and partly because it is more concentrated in the ICF than in the ECF, so it diffuses down its concentration gradient when it has the opportunity. The loss of positive potassium ions from the cell turns the inside of the membrane negative again (repolarization). This quick up­and­down voltage shift, from the negative RMP to a positive value and then back to a negative value again, is called an action potential. The RMP is a stable voltage seen in a “waiting” cell, whereas the action potential is a quickly fluctuating voltage seen in an active, stimulated cell. References Composition eBook & Resources Section: 11.03 ...
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