The diagram below shows a typical action potential in a nerve cell. In regards to this action potential, which one of the following is most likely? The afterhyperpolarization results primarily from increased pumping activity of the Na+/K+/ATPase. The duration of the action potential is between 10 and 20 milliseconds. An action potential produced by a very strong signal will likely be larger than one produced by a weak stimulus. At the peak of the action potential the membrane potential is about 0 mV. During the repolarisation phase, voltage-gated Na+ channels are likely to be inactivated
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Consider the following three diagrams of a nerve cell membrane. They show resting potential, depolarization, and hyperpolarization. Figure out which one is which, then draw them in the order they occur in a cell that undergoes an action potential
Katlin K.
Action Potentials A stimulus causes the nerve cell membrane to become (more / less) permeable to Na+. Na+ can then enter the cell as voltage-gated Na+ channels become activated and open. At rest, the membrane had a potential of - (please write a number) mV. As Na+ enters the cell, the inside of the membrane becomes more (positive / negative). The potential will tend to go toward (-80 / -55 ) mV. The process of (polarization / depolarization ) is occurring. This process causes changes in more Na+ channels so that even more Na+ enters. This is an example of a (positive / negative) feedback mechanism. The result is a nerve impulse. The membrane is completely depolarized at exactly (-50 / 0 / +30 ) mV. Na + channels stay open until the inside of the membrane potential is (reversed / hyperpolarized) at + 30 mV.
Joy C.
The membrane potential of a cell is determined by the relative permeability of the membrane to various ions. When acetylcholine binds to its receptors on the postsynaptic muscle membrane, it causes a massive opening of channels that are equally permeable to sodium and potassium ions. Under these conditions, $$V_{m}=\left(V_{K^{*}}+V_{N_{A}^{*}}\right) / 2$$ If $\left[\mathrm{K}^{+}_{\text {in }}\right]=140 \mathrm{mM}$ and $\left[\mathrm{Na}_{\text {in }}^{+}\right]=10 \mathrm{mM}$ for the muscle cell, and $\left[\mathrm{Na}_{\text {out }}^{+}\right]=150 \mathrm{mM}$ and $\left[\mathrm{K}_{\text {cut }}^{+}\right]=5 \mathrm{mM},$ what is the membrane potential of the neuromuscular junction of an acetylcholine-stimulated muscle?
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