A rapid change in the membrane potential of excitable cells such as neurons and muscles; this usually involves a steep rise (depolarization) followed by a steep fall in membrane potential (repolarization). The cell subsequently enters a short refractory period (hyperpolarized state) during which it cannot generate another action potential.
Questions tagged [action-potential]
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Action potential: why called "depolarization" when polarity is reversed, not removed?
During an action potential, the voltage shifts from the resting potential of -70 mV, to +30 mV, to then fall return back to the resting potential again of -70 mV. This reverse of the polarity, what is the reason it came to be called…
Tolka
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How does entry of Ca²⁺ to the myocardiocyte make it more contractible?
I'm trying to understand why an increase of Ca2+ entering into the cell, increases the force of the heart contractions. Based on what I have watched in many lectures videos on Youtube (this one- "interactive biology" for example on 4:45), Ca2+…
Alleged Biologist
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Accumulation of Na⁺ and Ca²⁺ in the myocardiocytes while having acute heart failure
Why is it necessary to have accumulation of sodium and calcium ions in the myocardium cells while having acute heart failure? Normally, at resting membrane potential, sodium and calcium are more outside of the cell than inside, then I expect to see…
Alleged Biologist
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Elements that make action potential to conduct quicker?
The texts, online materials describe the velocity of conduction of action potential depends on axon's length and cross sectional area e.g. short length and large diameter decreases the resistance. Myelin sheath increases the speed of conductivity as…
bonCodigo
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What happens to potassium after an action potential?
If I understand right, after repolarization, much of the potassium is outside the membrane and much of the sodium / calcium is inside. How does it get back to the original concentrations (i.e. potassium inside and sodium/calcium outside)?
arao6
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What happens when too much sodium flows in the cell due to a faulty voltage-gated sensor? What about too little?
The activation gate opens, signaling depolarization. Eventually, the inactivation gate closes, ending depolarization and beginning repolarization.
What is the physiological impact of the inactivation gate remaining open too long, letting in too…
chompion
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Can we have the action potential an AC current?
As well known brain are connected to our body by neuronal cells. it transmits and receives its data by action potential during neuronal cells. i wonder if any one can explain to me the properties of this current. can we consider this current as an…
