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 ...
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25 votes
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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 ...
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14 votes
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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, ...
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12 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 ...
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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 ...
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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 ...
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  • 1,199
7 votes
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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, ...
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6 votes
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What is the reason behind high resting membrane potential of pacemaker cells?

The pacemaker potential is interesting (to a biologist) as it involves your typical Na/K channels, Ca channel, as well as a funny current (If) or alternatively called hyperpolarization-activated ...
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  • 2,268
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 ...
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6 votes
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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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  • 666
5 votes

Similarity between a heart attack and a spasm

I was able to do some reading and research and I found some interesting information that was a). news to me. And b). the answer is yes... And no. A spasm can be the cause of a heart attack by causing ...
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  • 1,120
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. ...
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5 votes

How to analyse an ECG?

First bump is called P point, middle is QRS wave (as in Q-down, R-up, S-down), and last bump is T. Every feature is representation of electrical activity in certain region of heart. E.g. P bump is ...
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5 votes
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What does pain look like in wave form?

I don't want to comment about the nature of electric signals in neurons (as I know only little about physiology and neurophysiology). But here is a short answer that may already help you. Neuronal ...
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5 votes
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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?

Representative ion concentrations are shown in Fig. 1: The membrane is mainly permeable to K+. Because the Na+,K+-ATPase pumps K+ inside of the cell, it tends to diffuse outward again, thereby taking ...
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5 votes
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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 ...
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5 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 ...
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5 votes
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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 ...
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5 votes
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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 ...
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  • 4,296
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 ...
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  • 8,718
5 votes
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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, ...
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  • 1,495
5 votes
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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+ ...
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  • 51k
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 ...
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5 votes
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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 ...
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4 votes

Action potential changes in low sodium concentrations but constant osmotic pressure

High sodium extracellularly means an increased sodium concentration gradient across the membrane. This means there is a larger driving force for sodium to enter the cell once the sodium channels open ...
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4 votes
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How precise is EEG?

Electroencephalography has a good time resolution (milliseconds) but poor spatial resolution (several centimers). The usual estimated figure is that at least 50000 neurons need to fire simultaneously ...
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  • 181
4 votes
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Mechanisms of extracellular stimulation of neurons

Good question. Just to set some stuff straight: In contrast to a comment placed earlier, there is definitely a current flow between electrodes in neural tissue, as long as the impedance is not too ...
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4 votes

Why did life not evolve to use radio?

I just found a research about possibility of organism with loop DNA (Mostly bacteria) could use there DNA as antenna to transmit and receive radio wave around 1kHz http://www.wired.com/2011/04/...
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  • 459
4 votes
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How is membrane capacitance related to the increased speed of saltatory conduction?

Very nice question! I'll go through your three questions sequentially. Q1: Why does lower capacitance increase "the effectiveness of nearby nodes" or allow the depolarizing voltage to "travel not by ...
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  • 51k
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 ...
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