2-Minute Neuroscience: Action Potential


Welcome to 2 minute neuroscience, where I
simplistically explain neuroscience topics in 2 minutes or less. In this installment
I will discuss the action potential. The action potential is a momentary reversal
of membrane potential that is the basis for electrical signaling within neurons. If you’re
unfamiliar with membrane potential, you may want to watch my video on membrane potential
before watching this video. The resting membrane potential of a neuron
is around -70 millivolts. When neurotransmitters bind to receptors on the dendrites of a neuron,
they can have an effect on the neuron known as depolarization. This means that they make
the membrane potential less polarized, or cause it to move closer to 0. This chart shows membrane potential on the
y axis and time on the x axis. When neurotransmitters interacting with receptors causes repeated
depolarization of the neuron, eventually the neuron reaches what is known as its threshold
membrane potential. In a neuron with a membrane potential of -70 mV, this is generally around
-55 mV. When threshold is reached, a large number
of sodium channels open, allowing positively charged sodium ions into the cell. This causes
massive depolarization of the neuron as the membrane potential reaches 0 and then becomes
positive. This is known as the rising phase of the action potential. This influx of positive
ions creates the electrical signal known as the action potential, which then travels down
the neuron. Eventually the action potential reaches its
peak, sodium channels close and potassium channels open, which allows potassium to flow
out of the cell. This loss of positive potassium ions promotes repolarization which is known
as the falling phase of the action potential. The neuron returns to resting membrane potential,
but actually overshoots it and the cell becomes hyperpolarized. During this phase, known as
the refractory period, it is very difficult to cause the neuron to fire again. Eventually the potassium channels close and
the membrane returns to resting membrane potential, ready to be activated again. The signal generated
by the action potential travels down the neuron and can cause the release of neurotransmitter
at the axon terminals to pass the signal to the next neuron.

37 thoughts on “2-Minute Neuroscience: Action Potential

  1. This is great, but I worry it's too general, a lot of stuff isn't explained here that is key to understanding how the action potential is triggered, such as the temporal kinetics of the voltage gated potassium/sodium channels, or the probabilistic opening of them.

  2. Why so few subscribers and views? This channel is extremely underrated. People need to find out about it.

  3. In your video, you show that the potassium channel open at the peak, but I thought the potassium channels open earlier than that.

  4. Unresolved contradictions in the science of the origin of life. The membrane theory of biopotentials leads to a dead end. Watch the video for details: https://youtu.be/0yMTnXI6UEA

  5. If the cell membrane were hyperpolarized to a resting potential of -110 mV, what would be the effect on the potential opening of K+ channel?

  6. Hello I have a question that's it's so hard for me to find out it says action potential starts with deporalizaton or ends with hyperpolarization I think the correct is that it's starts with deporalizaton

  7. I am seriously crying right now because your videos have just helped me explain what I couldn't comprehend from rewatching my lectures the past 2 days. I was so stuck in this topic. Thank you so much for taking the time to create these videos!!

  8. Lowkey I feel like the 2 minute cap was a convenience thing (i.e. I'm not trying to watch a 10 minute video on APs), but I think you accomplish the same thing with 3 minutes. And that's a 50% increase in your current screen time fam. Consider it.

  9. Hyperpolarization….hmm, must be what is happening when I suddenly can't recall the name of a famous person or something else I've known all my life, but then I suddenly can recall it, perhaps seconds, minutes or hours later (repolarization?).

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