The discussion centers on the origin of electrical signals in nerves, specifically action potentials, which are generated by the movement of sodium (Na+) and potassium (K+) ions across cell membranes. The participants explain the mechanisms of ion channel operation during action potentials, including depolarization and repolarization phases. They also discuss the effects of various paralytic venoms, such as latrotoxin from black widow spiders, and neuromuscular channel blockers like tubocurarine and suxamethonium, which manipulate ion channel activity to induce paralysis. The conversation highlights the importance of the Hodgkin-Huxley model in understanding these processes, while also addressing criticisms and alternative theories regarding ion channel behavior.
PREREQUISITESNeuroscientists, pharmacologists, medical students, and anyone interested in the mechanisms of nerve signaling and the effects of toxins on neuromuscular function.
RogueSpidor said:Many paralytic venoms used by spiders and other creatures affect the opening and closing of those channels. A paralytic will work either by causing the channels to open wide, causing the signals to continue non-stop, or slam shut, so no signals are sent and the muscles don't contract at all. A relaxing paralytic is not useful to a hunting, arboreal spider, since it will likely result in their prey falling out of the tree, making it hard for the spider to find and eat it. However, a convulsive paralytic will cause the prey to continue to grip, making it less likely to fall out of the tree. It does this by inducing the neurons to fire continuously. The black widow venom (latrotoxin) is an example of this, and is characterized by severe muscle cramps throughout the body, and particularly in the abdomen.
Molok said:I was wondering if someone could tell me where the electricity used for the nerves come from? and could someone with a good knowledge of the matter please explain how it works to me? :)
At a glance, wikipedia seems to do a decent job: http://en.wikipedia.org/wiki/Action_potentials
somasimple said:This works only if you consider that gradients remain constant. But it is impossible (at molecular level).
In the same way, this process is largely reduced and non constant. The active transport is then activated when necessary. The mystery of the "lost" energy consumption is solved.At resting potential, the concentration gradients are maintained by active transport.
Soma Simple, if you'll fully explain what you think is wrong with the Hodgkin-Huxley model then I can show you what your mistake is.
somasimple said:here =>
http://www.somasimple.com/forums/showpost.php?p=39321&postcount=66
Please, explain how it is possible, in an equipotential wire, to have opposite currents ?
And how it is possible that a resistance is able to create energy?
Cincinnatus said:What are you talking about? No one is claiming "equipotential wires have opposite currents" or that "resistances create energy" I'm not even sure what you mean by these.
Is there a biologist in the forum?Albert Einstein said:The important thing is not to stop questioning. Curiosity has its own reason for existing. One cannot help but be in awe when he contemplates the mysteries of eternity, of life, of the marvelous structure of reality. It is enough if one tries merely to comprehend a little of this mystery every day. Never lose a holy curiosity.