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 ...
- 44.1k
27
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 ...
- 29.7k
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, ...
- 52.3k
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 ...
- 29.7k
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 ...
- 52.3k
7
votes
Why does the intensity of an action potential once generated at the trigger zone remain undistured throught the axon?
Actually, it would be better to say that action potential does not travel but is regenerated anew in a sequence along the axon.
I would like to elaborate how this happens and why this is the reason ...
- 1,229
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, ...
- 44.1k
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 ...
- 44.1k
6
votes
How's the membrane potential restored to resting state after hyper polarisation?
The Na,K-ATPase restores negative membrane potentials. When a cell is hyperpolarized, leaky K+ channels take care of that. Leaky K+ channels are always open. Generally, K+ has the tendency to diffuse ...
- 52.3k
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 ...
- 44.1k
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.
(...
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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 ...
- 193
5
votes
Accepted
Can an electrocardiogram be recorded with a single electrode?
Short answer
Any electrophysiological recording of potentials, including the electrocardiogram (ECG or EKG), measures a potential difference. Hence, two or more electrodes are necessary.
Background
...
- 52.3k
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.
...
- 52.3k
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 ...
- 712
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 ...
- 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 ...
- 9,024
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, ...
- 1,515
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+ ...
- 52.3k
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 ...
- 52.3k
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 ...
- 3,313
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://...
- 44.1k
4
votes
Software recommendation for protein in electric field modeling?
MD
Broadly this could be attempted with Molecular Dynamics simulations. As you discovered in your search, one of the most popular softwares is free: GROMACS. This is an atomistic approach to the ...
- 11.3k
4
votes
Why does the intensity of an action potential once generated at the trigger zone remain undistured throught the axon?
Descriptive Answer- A nerve impulse is the movement of an action potential as a wave through a nerve fibre. A wave of negative charge on the surface of an axon marks the position, at any moment, of ...
- 14.1k
4
votes
Accepted
What physical or mental actions can be picked up by EEGs?
Many EEG responses are swamped in random brain activity, artifacts and background noise. A single movement typically doesn't evoke measurable activity, because its amplitude is so small with respect ...
- 52.3k
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+...
- 52.3k
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 ...
- 44.1k
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 ...
- 697
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 ...
- 52.3k
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 ...
- 10.3k
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