# Search results

thanks cabraham. berkeman, it beats me - this is why I asked :S
2. ### Testing gradient against a value

Homework Statement I have 25 pairs of values. I have a gradient and want to test if this gradient is significantly different from 1. Which stats test do I use? I thought of using a one-sample t-test, but how are you meant to put 25 gradients in the test!??? thanks...

how do they improve high-frequency transmission (and not low-frequency?) ? I'm a biologist... Thanks
4. ### Mass moment of inertia of an irregular area

Hi. Please help. I'm struggling to find the mass moment of inertia of an area. Please see picture. I already have the centroid of the area, and the exact area. How would I find the mass moment of inertia of this area about its centroid? I tried using AutoCAD, but it gives you the...
5. ### MathCAD - separation of real and imaginary parts of a complex variable

yeah but it doesn't work to separate out the components...
6. ### MathCAD - separation of real and imaginary parts of a complex variable

Hi guys, just wondering whether you could help. I've got a complex number in terms of a lot of variables, and need to separate it into its real and imaginary parts. How do I do that? I spent past hour trying to look for tutorials, unfortunately none tells you how to do it...
7. ### Bag of coffee bean

Recently I bought a bag of coffee beans from abroad on a plane, now the bag is very inflated. I want to take the bag on a plane again, would it burst?
8. ### Irreducible complexities

actually I've got some ideas but have work for tomorrow.. will post later
9. ### Irreducible complexities

we had a lecture on intelligent design (or should I say - one against ID). the lecturer went into great detail as to how some complex systems that are apparently irredicubly complex can actually be taken apart, and the system still works. e.g. the blood clotting system. what I don't...
10. ### Donnan Equation

here is the Q, can't do the chloride part.
11. ### Donnan Equation

I don't have the relative permeabilities.
12. ### Donnan Equation

How do you adapt the Donnan Equation to 3 difffusible ions?
13. ### Medical Chemical and Electrical transmission

Yes but we are discussing one individual muscle fibre which is only innervated by one nerve?
14. ### Medical Chemical and Electrical transmission

Are you talking about tetanus of muscle contraction, so higher frequency allows maximum tension to increase because muscles are stimulated before they fully relax? can you clarify ths bit please?
15. ### Medical Chemical and Electrical transmission

BUT: a neuromuscular junction is an atypical chemical synapse:it is much simpler, with only one postsynaptic receptor type, only excitatory signals, and often endplate potentials are suprathreshold so 1AP => 1 contraction. therefore what you've argued does not apply to the neuromuscular junction?
16. ### Medical Chemical and Electrical transmission

Is it correct to say: signal along muscle is electrical because we want a 1:1 process i.e. 1AP=1contraction, if grading of AP occured then the system would not work as you cannot have a half contracting muscle but at the neuromuscular junction, you either get a contraction, or you don't; and...

18. ### Medical OBEs/Astral Projections

Why are the laws of physics defied?
19. ### Medical OBEs/Astral Projections

Is there ANY scientific basis of OBEs or Astral Projections, or remote viewing?:confused: and whether it is possible or not to project astrally?
20. ### Medical Action Potential

Is the inward current chloride ions? Does the direction of "current" take into account of the charge of the ion? e.g. when you say inward current of Sodium - sodium ion is positive?
21. ### Medical Action Potential

This is about voltage clamping: When Hodgkin and Huxley voltaged clamped a nerve - when hyperpolarised there was a small inward current, why is that? and when they used a depolarising clamp, there is firstly a brief capacitative current - this current is outwards, why?:confused:
22. ### GABA(A) Receptors

In the lecture handout it says "When cells are hyperpolarised the result is a depolarisation towards threshold." What does this mean?:confused:
23. ### Medical Chemical and Electrical transmission

but why can't you have electrical transmission at the neuromuscular junction?
24. ### Medical Chemical and Electrical transmission

But wnat you just said does not argue against a purely electrically based system. Axons travel much slowly because it's not a current (well except for passive conduction) but is achieved electrochemically.
25. ### Medical Chemical and Electrical transmission

I did not mean the signal can travel in both directions - i meant APs in opposite directions without crossing each other.
26. ### Medical Chemical and Electrical transmission

Surely such biological systems with only electrical connections would still work if you prevent cross-interference between signals (we already have those in nerve fibres - signals travel in opposite directions but the signals are insulated by myelin). So why can you not extend this network to...
27. ### Medical Chemical and Electrical transmission

Is chemical coordination more complex then? I've always though an electrical system is more recent and complex (which is why we have it in the brain). Why do you need chemical transmission at the neuromuscular junction though? We have current neurotransmitters which bind to AChR sites for...
28. ### Medical Chemical and Electrical transmission

Transmission of a message electrically can work if we put extra myelin sheath around axons. So you are saying chemical transmission represents an analogical system? I can see your point. But we have electrical synapses in the brain, so why won't it work for the rest of the body, presumbly...
29. ### Medical Chemical and Electrical transmission

I know the question asks why the nerve transmission is electrical, but I don't think it wants 'because its due to charged particles'. It's asking for adv. and disadv between the two. I've had discussions with others - but an electrical homeostatic system can work but we just haven't evolved one.
30. ### Medical Chemical and Electrical transmission

Signal propagation along motor nerves or fibres of muscles is electrochemical (or electrical)l, whereas transmission at the neuromuscular junction is chemical, Why is that?