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Questions tagged [electrophysiology]

The study of the electrical properties of biological cells and tissues.

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33 votes
3 answers
36k views

Why is saltatory conduction in myelinated axons faster than continuous conduction in unmyelinated axons?

How does spacing apart sodium and potassium channels allow the action potential to travel faster down the axon? This is the reason always cited for saltatory conduction and myelination, but my mental ...
user7924's user avatar
  • 333
5 votes
1 answer
2k views

If the average resting potential of a neuron is -70 mV, why is there such a high ratio of potassium ions inside relative to out?

My bio teacher was discussing the ratios of different ions inside versus outside the cell. $$\text{OUT:IN}$$ $$\text{K}^+ (1:20)$$ $$\text{Cl}^- (11.5:1)$$ $$\text{Ca}^{2+} (10000:1)$$ $$\text{Na}^+...
Stan Shunpike's user avatar
9 votes
1 answer
3k views

What keeps the resting potential of neurons constant at -70 mV?

I know the sodium-potassium pump pumps out 3 Na+ ions and pumps in 2 K+ ions per reaction so the negative charge in the axon increases. However, once the voltage (difference of charge inside and ...
hello all's user avatar
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10 votes
2 answers
27k views

How is membrane capacitance related to the increased speed of saltatory conduction?

Here is the original question which inspired my question. As explained by the answers there, the reason saltatory conduction in myelinated neurons is faster than non-myelinated conduction is because ...
stochastic13's user avatar
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6 votes
1 answer
2k views

Why do larger diameter myelinated axons have greater conduction velocities than small diameter myelinated axons?

A canonical statement I have frequently read is that "large diameter axons conduct action potentials at faster velocities than small diameter axons". After recently learning the effect of increased ...
S.C.'s user avatar
  • 375
1 vote
0 answers
169 views

Are large cell bodies of neurons harder to depolarize than small cell bodies of neurons?

In order for the axon to initiate an action potential, we know that the axon initial segment must be brought to threshold. So my question is as follows: Say we have the minimum charge input, "X", ...
S.C.'s user avatar
  • 375
8 votes
2 answers
570 views

What does pain look like in wave form?

I am interested in understanding what "pain" and "hot/cold" look like, as far as waves signatures (signal processing) go. My general understanding of how pain (nociceptive pathways) and hot/cold (...
smeeb's user avatar
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7 votes
1 answer
6k views

Why do neurons have a negative resting potential?

Neurons expend the majority of their energy powering ion pumps to maintain the chemical gradients that power their electrical activity. To have a negative resting potential, neurons leak potassium ...
Luke's user avatar
  • 658
5 votes
1 answer
110 views

At What Rate Do Ions Leak Out of a Plasma Membrane Segment That Has No Ion Channels?

In reading about the purpose of myelin during action potential propagation, I came across a point of confusion. From what I understand, one of the primary "benefits" of myelin is that it aids in ...
S.C.'s user avatar
  • 375
5 votes
0 answers
134 views

How to measure Na/K channel activation at the membrane level?

Assume that there are two different signals occurring on the ECG - during depolarization and repolarization in the standard ECG. I was advised not to use the standard ECG in measuring the exact ...
Léo Léopold Hertz 준영's user avatar
4 votes
1 answer
1k views

Doubling the concentration of extracellular calcium hyperpolarizes a neuron. Why?

I was doing some back of the envelope calculations to try to answer this question in more mathematical terms. Essentially the question states: Why does increasing the extracellular potassium ...
xelo747's user avatar
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4 votes
1 answer
866 views

Mechanisms of extracellular stimulation of neurons

When stimulating a group of neurons with an electrode, let's say we put it in a region that contains axons, what is the mechanism by which the axons are stimulated? I've been told electrodes (...
Pepe Mandioca's user avatar
4 votes
1 answer
196 views

Do electric eels produce current as they just move about, and how/why?

https://www.youtube.com/watch?v=y9wktSQdyaE This video demonstrates how an electric eel can supposedly produce up to 800 watts, and power a Christmas tree, which is very topical (a late Merry ...
Johnny's user avatar
  • 273
2 votes
0 answers
162 views

Living potato clock? [duplicate]

Could a potato stay alive and power a clock while growing in the ground? I know how a potato clock works as a electrochemical cell and involves chemistry, but I am only interested in a growing ...
Muze's user avatar
  • 1
1 vote
1 answer
214 views

Why don't membrane potentials violate the principle of electroneutrality?

The principle of electroneutrality states that the number of anions and cations in a solution must be the same, i.e., that there will be no charge excess in any side of the membrane separating two ...
TheAnonymous's user avatar
1 vote
1 answer
205 views

In the PR segment of an ECG, how come there's no current flowing?

I don't really know how to phrase the question, but to put it as clearly as I can, I don't get why it is the P wave "flattens down" when the atria have completely depolarized. I get that the ...
Dahen's user avatar
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