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The use of methods from the physical sciences to aid in the study of biological systems.

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18 views

What is (are) the medium of conduction for an electrical current with an external source in the human body?

I am trying to get some background for some personal research I am doing into the effects of Electro Convulsive Therapy. I don't understand how electric current from an external household source, say, ...
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9 views

Electrical mobility of biological relevant ions in solution

I've been trying to find references of electrical mobility of ions relevant in neuroscience (K+, Cl- Ca2+, HEPES). This is important to calculate liquid junction potentials of electrophysiology ...
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0answers
17 views

Pressure on tympanic membrane

How much pressure can you create on the eardrum, if you press your ears torwards your head with your hands? For example water can create lots of pressure on the ear, if we dive too deep, but how much ...
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0answers
21 views

What waste products do cells secrete in culture, and at what rate?

I am designing microfluidic chips for mammalian cell culture. One aspect I am interested in modeling is the rate at which I must renew media to ensure that: Cells receive enough nutrients Cytotoxic ...
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1answer
58 views

Can multiple antibodies bind the same antigen?

Given the size difference between small molecule antigens and antibodies is it ever possible for multiple antibodies to bind to the same antigen if they recognize different domains on that antigen? ...
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1answer
27 views

Square-cubed law and health

Does the square-cubed law lead to possible health detriments for taller people? I'm not sure what the optimum height is for humans (e.g. due to their cross-sectional bone density constraints), but ...
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1answer
23 views

Is it possible to induce protein activation via frequency-specific mechanical waves? [closed]

Would it be possible to induce shape changes in specific proteins by providing specific frequencies of mechanical waves in a thermostatically controlled environment such that those proteins may be ...
2
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0answers
45 views

How can diving with 100% oxygen not destroy your lungs? [closed]

It is possible this should be moved to physics, depending on the nature of the answer (i.e. if the reason is physical). But I suspect the explanation is biological, so I posted it here. Sometimes ...
3
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1answer
50 views

Fraction of channels open at equilibrium

I found the formula for the fraction of channels open at equilibrium for a three-state mechanism (Colquhoun's paper in the microelectrode book http://www.utdallas.edu/~tres/microelectrode/me.html) k1 ...
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2answers
57 views

Are resonances the reason receptors work?

From Visual phototransduction - Wikipedia: When struck by a photon, 11-cis retinal undergoes photoisomerization to all-trans retinal which changes the conformation of the opsin GPCR leading to ...
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1answer
29 views

Is summation linear in a passive membrane?

I am not too sure what it means for summation to be linear? I am running a simulation and as I decrease time for the second EPSP the amplitude decreases. Does summation being linear mean that there is ...
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0answers
203 views

Passive diffusion of non-polar molecules across plasma membrane

I understand that small, nonpolar molecules that can dissolve in the hydrophobic (nonpolar) part of the plasma membrane are able to cross it and passively diffuse into or out of the cell. But doesn'...
4
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1answer
347 views

Why does UVA penetrate deeper than UVB, though it's weaker?

Even though UVA radiation ranges in longer wavelengths (315–400 nm) than UVB (280–315 nm) and thus is less energetic, UVA is able to penetrate deeper into the skin and even reach the dermis. Why is ...
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0answers
20 views

Why are Chromosomes that stained with DAPI didn't seem emanate a fluorescent light?

I am currently working with chromosomes imaging using Fluorescence Microscope. The chromosomes were stained with DAPI and illuminated by light whose wavelength 360-370 nm. The problem is chromosomes ...
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0answers
35 views

effect of arterial vasocontriction on the pressure in arteries

if experimentally one induces smooth muscle contraction on an artery and cause it to constrict, keeping the cardiac output same and also the arteriolar resistance(total peripheral resistance) the same ...
2
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0answers
109 views

What is the biological relevance of RIPPLE phase in membranes?

I was reading about ripple phase in bilayer lipid membranes which is described here as a meta-stable state between lamellar tilted crystalline and lamellar fluid state. It is also known that ripple ...
2
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1answer
51 views

Causes of the stochastic behaviour of voltage-gated ion channels

I came up with the following electro-mechanical model of a voltage-gated ion channel, resp. of its voltage sensor as described here and here. The voltage sensor is a bistable system with two local ...
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0answers
52 views

law of laplace and pressure developed in arteries

in arterioles the pressure depends on the impedance of the vessel(elasticity and youngs modulus) cardiac output pre arteriolar resistance what i want to ask is will the pressure also depend on law of ...
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0answers
29 views

Calcium and nitric oxide: does a numerical relationship exist?

Currently, I am trying to understand how nitric oxide and calcium are related during the production of the former (I am not a biologist nor a chemist, so my knowledge about these topics is very poor). ...
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0answers
81 views

How does isometric contraction work in detail?

If it's not the contraction of the sarcomeres alone that is responsible for the contraction of the muscle fibres they are part of (and of the muscle that the fibers are part of): what is it then? How ...
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1answer
310 views

How can some residues in the active site of enzymes be protonated with a pKa < 7?

It is reported in many papers, that some residues in the active site of enzymes need to be protonated to get functional enzyme, where these residues have a low pKa (for let us say 5). How can that ...
2
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0answers
31 views

Validity of Acoustic Weapon Effects on Biological Organisms?

There is alot of rather contradictory information present on the biological effects of acoustic weapons with a bevy of scientific articles claiming that they cause harm to biological organisms with ...
4
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1answer
88 views

What is the point in the Neuromuscular Junction?

Surely a direct connection (i.e. an electrical synapse) between motor neurone and the sarcolemma would allow for much faster neuromuscular transmission? It is my understanding that chemical synapses ...
2
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0answers
44 views

Are trees still carrying their leaves more likely to be felled by an autumn storm?

Is there evidence that trees still carrying their leaves are more likely to be felled by an autumn storm than trees already having lost their leaves? At first sight this seems plausible (and might be ...
2
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1answer
148 views

How interrelated are computational biology and biophysics? [closed]

I am considering applying to Ph.D. programs, and am not sure what direction to take. I'm hoping you all can help me out. I have a background in both biology (molecular focus) and physics (condensed ...
2
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1answer
52 views

Calcium concentration in activated dendritic spines?

What are the typical calcium levels reached in single postsynaptic spines following activation of NMDA receptors by an EPSP or backpropagating spike? Everyone seems to refer to that one Neuron paper (...
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1answer
88 views

Mathematical relationship between membrane conductance and conduction velocity?

By what factor would the myelin need to decrease membrane conductance (gm) if you wanted conduction velocity in a 10 μm myelinated mouse axon to be 100 times faster than in a 10 μm unmyelinated mouse ...
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2answers
140 views

What are the structural factors affect enzyme's Km?

Is there any rules (should not be exact), to estimate the kinetic changes in an enzyme if I did any mutation on it? If I cannot estimate the new kinetic values, is it possible at least to clarify or ...
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2answers
42 views

Does opening of ion channels alter the membrane potential directly?

Does the opening of a voltage-gated ion channel (i.e. the change of configuration of the protein) by an appropriate local change of the membrane potential directly and significantly alter the membrane ...
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1answer
49 views

How are fMRI responses to auditory stimuli measured?

How can fMRI experiments be conducted which measure the response to auditory stimuli (e.g. music) when the apparatus makes such loud, nasty, and distracting noises? Are there quieter MRI tomographs in ...
1
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1answer
93 views

Half-life and production rate of ion channels

There are "not millions, not a few hundred...somewhere in between (some tens of thousands)" of ion channels in a neuron. Given the number of ion channels per neuron, knowing the half-life of ion ...
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1answer
32 views

Measuring depolarizations over the membrane

Measuring the rest potential of a membrane is relatively easy and straight forward: put one electrode inside the neuron, the other one (the "counter electrode") outside the neuron. Because ...
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1answer
37 views

Are ion channels/resistancies in Rall's model voltage-independent or not?

In the description of the electrical circuit that models a piece of membrane in Rall's Scholarpedia article on Ralls model, I read: "[...] this conductance [$G_e$] is zero under resting ...
2
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0answers
190 views

Can a mathematical function be assigned to ECG diagram?

This is a 12 lead electeocardiogram of a 26 year old male: This is the graph of function $5sin(7x)sin(.5x)cos(3.25x)$ This graph look quite similar to the ECG diagram.After sketching this graph, I ...
2
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1answer
57 views

What would EEG recordings reveal if their resolution was better?

1. Temporal resolution Of course, we would see higher frequencies. But would these be informative? Aren't the frequencies measured today near the border to noise? 2. Spatial resolution I guess LFP ...
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1answer
143 views

Speed of passive transport of ions in the dendrite

I tried hard to get them, but I didn't get any numbers. My (subjectively) best Google search was for "speed propagation post-synaptic potential". My question is: How fast are ions transported ...
5
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3answers
123 views

What is measured by electroencephalograms and local field potentials?

In the Scholarpedia article on local field potentials (2013), I read: The current view is that EEG and LFPs are generated by synchronized synaptic currents arising on cortical neurons, possibly ...
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0answers
52 views

What is the lowest atmospheric pressure that humans can survive in naked given any atmospheric composition of gases?

There are plenty of similar posts; having read them, they do not answer my question. Most attempts at answers rely upon low atmospheric pressure conditions on Earth, which have 20.9% oxygen. Answers ...
5
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1answer
75 views

white blood cells and cancer cells transport through lymphatic vessels

It is a well-known fact that both of these cells can reach the lymphatic vessels from interstitial space. How does it do so physically? Are there any mathematical models describing this process? It ...
4
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0answers
137 views

Protein phosphorylation in the cytoplasm. Typical time scale?

Is there a typical protein phosphorylation rate in the cell cytoplasm under physiological conditions, or at least an upper-bound? Suppose a protein $A$ is being phosphorylated into $A^*$ with the ...
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4answers
251 views

Are there known life forms that are able to transform mechanical energy into chemical energy?

Are there known life forms that are able to transform mechanical energy into chemical energy? This question asks a similar subject, but more specific and has no answers. The background of this ...
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0answers
22 views

Is striated muscle anisotropic in terms of diffusion?

Roughly speaking, in striated muscle tissue (such as in the deltoid or other common sites for intramuscular injection), does the diffusion of a fluid have the same diffusion constant irrespective of ...
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0answers
56 views

What structures (i.e. organs) are suspended by tensile forces?

In several areas of biomechanical literature I have read, the concept of "tensegrity" has arisen. Definitions are as follows: “The integrity of a stable structure balanced by continuous structural ...
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0answers
291 views

How much time human eye needs to focus on an object?

Here's the setup: i ride in a train at 100km/h and watch at the trees out of an 1.5m wide window sitting 2m away from it (so, the window takes only 45° for me). Trees outside are moving, and at ...
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0answers
32 views

Will charged water ions sprayed onto plants keep insects off?

I had stumbled on an article about a Dutch firm that devised an irrigation system that used mist of ionized water droplets that they claim keeps insects away from the plants. This break through would ...
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1answer
59 views

What happens when lightning strikes us? How is it fatal?

How does a person die due to lightning? Is the cause of death similar to that due to electric shock? Why do minor shocks don't show similar effects in small magnitude (like paralysis in that part)?
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0answers
37 views

Why do nerve fibres rotate?

Background: Lemniscus (Latin lēmniscus, ribbon) is a strap of second order nerve fibres which twist as they ascend to the brainstem. Why do these these nerve fibres rotate? What could be the ...
4
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2answers
418 views

Should there be separate Ramachandran plots for an amino acid in different contexts?

I understand the nomenclature of the phi and the psi angles of the alpha-Carbon atoms in protein stucture, but I am confused by the Ramachandran plot. Each alpha-Carbon atom (magenta) makes two ...
3
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1answer
1k views

How many ion channels on average must there be in one µm2 of neuronal membranes?

If the conductance of a single ion channel is 1pS and its capacitance per cm2 is 1uF and the time constant for a human neuron is 1ms How many ion channels on average must there be in one µm2 of ...
2
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1answer
172 views

Health effect of electromagnetic and acoustic waves on brain function [closed]

What if any effects are there on brain function from prolonged exposure to electromagnetic or acoustic stimulation?