Skip to main content
30 votes

Why do blood vessels in the eye not obstruct vision?

Avoid the fovea Figure 2 from the same paper shows the distribution relative to the fovea: As you can see, it's pretty much devoid of this superficial vasculature, so anything you are directly ...
Bryan Krause's user avatar
  • 46.1k
28 votes
Accepted

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

Short Answer Myelination acts as an electrical insulator and allows saltatory propagation. By reducing membrane capacitance and increasing membrane resistance, myelination increases the velocity of ...
theforestecologist's user avatar
14 votes
Accepted

Why is Fast Fourier Transform applied to raw EEG data?

Fast-Fourier Transform (FFT) transforms a signal from the time domain into the frequency domain. Basically, any time-dependent signal can be broken down in a collection of sinusoids. In this way, ...
AliceD's user avatar
  • 52.5k
13 votes

Why do blood vessels in the eye not obstruct vision?

You CAN see your blood vessels! Following-up from Bryan Krause's answer: Bryan mentioned that the blood vessels are typically not visible partially because they are unchanging (i.e., static). In ...
theforestecologist's user avatar
11 votes

Why are nerves blocked even though potassium channels are not blocked?

In general, action potentials are initiated by an inflow of Na+ that depolarizes the neuron. Only after that, K+ channels open up that re-polarize the membrane potential to get the neuron back in ...
AliceD's user avatar
  • 52.5k
7 votes
Accepted

Organic battery?

I don't have the math at hand for the actually energy efficiency, but let's just start from the storage capacity. Basically, an electric eel wouldn't make a very good battery. They could be a decent, ...
Bryan Krause's user avatar
  • 46.1k
7 votes
Accepted

Why does hypercalcemia cause muscle weakness, yet hyperkalemia causes muscle excitation?

You're correct about your reasoning for potassium; high extracellular potassium concentration reduces the concentration gradient of potassium across the membrane, pushing the reversal potential for ...
Bryan Krause's user avatar
  • 46.1k
6 votes

How do plants store energy by potassium battery?

I'll give it a layman's attempt in sort of an "ELI5" approach. I hope the analogy isn't too simplistic, and please don't take it too literally. How do plants use K+? Plants control K+ concentrations ...
Bryan Krause's user avatar
  • 46.1k
6 votes
Accepted

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

You are right - the 800 Watts are not constantly produced: There are three types of electrical discharge: (i) low voltage (ii) high voltage doublets or triplets and (iii) high voltage high frequency. (...
dtadres's user avatar
  • 666
5 votes
Accepted

Why nerve fibre is infatiguable?( is my conjecture correct?)

One can imagine that each action potential causes a small amount of $\ce{Na+}$ goes inside the cell, and a small amount $\ce{K+}$ goes outside the cell, thus weakening the electrochemical gradient of ...
xelo747's user avatar
  • 722
5 votes

Why is Fast Fourier Transform applied to raw EEG data?

Any periodic waveform can be produced by adding up a series of sin waves of the appropriate frequency and amplitude. The FFT looks at a complex waveform and calculates those frequencies and ...
Mark's user avatar
  • 193
5 votes

Are Gram negative bacteria classified as such because of their negative membrane potential?

Short answer The distinction between Gram positive (Gram+) and negative bacteria (Gram-) has absolutely nothing to do with membrane potentials; it is all about the Gram staining procedure. ...
AliceD's user avatar
  • 52.5k
5 votes
Accepted

Are resonances the reason receptors work?

Photoreceptors themselves dont act as oscilators, a single receptor is either 'on' or 'off' - it does not respond differently to different wavelenghts. Humans have Trichromatic vision, which means ...
Nicolai's user avatar
  • 4,391
5 votes

Can the human body utilize electricity?

No, the human body cannot utilize externally applied electricity. Applying electricity to the body will either have no effect, if the amount is small, or will disrupt normal functions of the body or ...
mgkrebbs's user avatar
  • 9,054
5 votes
Accepted

Which kind of electrical brain activity is associated with consciousness and why?

Gamma band oscillations (GBO) (Wikipedia) (NCBI) are 30-90 Hz electrical waves generated by the brain and are thought to possibly be associated with cognition and consciousness (Panagiotaropoulos, ...
Jam's user avatar
  • 1,506
5 votes
Accepted

The information carried by nerve signals

Neural info is contained in spike trains, mainly in terms of spike frequency and related parameters. These spike trains in individual neurons can be measured by techniques like patch clamp and Ca2+ ...
AliceD's user avatar
  • 52.5k
5 votes

What is the maximum electric potential that can occur in the human body?

To the best of my knowledge, the potential difference across the hair cells in the inner ear (cochlea) (Fig. 1) is the highest in the (human) body. It is about 120 mV, mainly due to the exceptionally ...
AliceD's user avatar
  • 52.5k
5 votes
Accepted

Why is the current flow shown to be flowing from the negative area towards the positive area?

By convention, positive current is assumed to be the direction of flow of positive charges. The trouble is that in many common situations (like this one), the current is actually carried by electrons ...
Charles E. Grant's user avatar
5 votes
Accepted

Ischemia-induced deploarization in excitable cells

Inward-rectifying means positive current passes more easily in the inward direction, however it won't flow differently than the membrane voltage and reversal potential dictate. See for example https://...
Bryan Krause's user avatar
  • 46.1k
4 votes

Why does the nerve action potential needs potassium?

The action potential is mediated by the opening of Na+ channels, which happens in the order of milliseconds (e.g., Aldrich & Stevens (1987)). Repolarization occurs through the opening of K+...
AliceD's user avatar
  • 52.5k
4 votes
Accepted

Is the ACh receptor more permeable to sodium ions?

Short answer No. There are differences in Na+ versus K+ permeability, but you have it backward: potassium is actually slightly more permeable; however, these differences are not the only factors ...
Bryan Krause's user avatar
  • 46.1k
4 votes
Accepted

Where does this equation in the electrophysiology literature form come from?

They chose that equation mainly because of numerical simplicity. It can fit the rates $\alpha$ and $\beta$ for all the ion channel particles in the model. The theoretical foundation for the ...
heracho's user avatar
  • 737
4 votes
Accepted

What is the significance of the amplitude of brain waves?

Brain waves are a colloquial term for EEG recordings. EEG recordings are gross potential recordings, in other words, they represent the responses of thousands of neurons together. Much of the ...
AliceD's user avatar
  • 52.5k
4 votes

How many Watt-hours can an electric eel produce in a day?

This research states that an eel whose size is 90 cm can provide 6.05 mW, which is 145 mWh every day. They say you'd need 165 eels to be able to read for 24 hours using a 1W lightbulb like the one on ...
bandybabboon's user avatar
  • 10.4k
4 votes

Why do larger neurons have less cytoplasmic resistance?

Neurons are like leaky cables. If you make them longer, the resistance increase (along the long axis); if you make them thicker (larger cross-sectional area), the resistance decrease. The word "...
X Zhang's user avatar
  • 354
3 votes

What signal processors comprise an Event-Related Potential system for EEG?

Event-related potentials are an issue in many aspects of physiology, not just in EEG analysis, so this answer is more general. The main problem is that electrical or other signals that are associated ...
EdM's user avatar
  • 720
3 votes
Accepted

Why summation takes place at Initial segment?

Why don't EPSPs travel passively through axons? EPSPs decay over distance. The decay is described by the length constant, which can be calculated based on the electrical properties of some ...
Bryan Krause's user avatar
  • 46.1k
3 votes
Accepted

Minimal viable EEG equipment for dissertation research on BCI / BMI

I have been working with BCI since some time and would recommend you to try these ones. They all have been widely used in MS/PhD research and their results are more or less accepted everywhere: ...
Failed Scientist's user avatar
3 votes

What are tail currents?

OK, I know this is old, but here goes. The tail current is the current at -55mV after the voltage step, here: The current shrinks as the voltage changes, this causes a massive shift in the driving ...
Oliver Houston's user avatar
3 votes
Accepted

Entropy during neuronal signaling

In my view, thinking of entropy as something biological life has "wants" about is a bit mistaken. In general, entropy arguments regarding biology run into a major problem in that the interesting ...
Bryan Krause's user avatar
  • 46.1k

Only top scored, non community-wiki answers of a minimum length are eligible