Are neurons in humans different of the ones of other animals?

  1. fluidistic

    fluidistic 3,286
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    Are neurons in humans different of the ones of other animals like spiders for example? In other words if one shows you a neuron under the microscope, can you identify from which animal it comes from?
     
  2. jcsd
  3. Pythagorean

    Pythagorean 4,580
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    The first highly-descriptive, successful neuron model was designed from a squid axon (The Hodgkin Huxley model) because they have giant axons that those old electric probes could actually take meaningful measurements from.

    We now use the Hodgkin Huxley model on mammals, too. In fact, I've used a genetic algorithm to tune a model designed for mollusks to match a rat neuron.

    As far as morphology and form (looking at it under a microscope) I don't know. Given two animals of the same size, they few I have seen all look the same to me, but maybe there's some expert that knows a trick to tell the difference. Certainly, a squid axon is going to be much bigger than any human axon. But for two animal sof the same size, I don't think there's a lot of differences except for maybe in the case of different phylums. Even then, in my brief work on C. elegans, I didn't see much difference, but I'm a laymen as far as molecular biology is concerned.
     
  4. Monique

    Monique 4,700
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    Neurons in a single organism can already look very different, but a clear structural example is that Drosophila neurons don't have a myelin sheath and thus no nodes of Ranvier. Glia do wrap the neurons though:
     
  5. fluidistic

    fluidistic 3,286
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    Ok thanks a lot, that's very interesting.
    I also wonder what happens to the ions that are exchenged via synapses between different neurons. Are some of them lost, and if so where do they go? I guess there's some loss, otherwise one could eat some potassium, calcium, etc. at birth and the brain would never need it again.
    I also find surprising the fact that all animals require many different type of ions such as sodium, potassium and calcium for their brain to function. I would not have thought that bees, ants for example or snails would have needed them.
     
  6. Pythagorean

    Pythagorean 4,580
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    Neurotransmitters are exchanged via synapses, not ions. And they get taken back up (a process creatively named reuptake). The basis of some pharmaceutical drugs (especially anti-depressants) is that they inhibit reuptake, allowing the neurotransmitter to hang around in the synapse longer to greater effect.

    K/Na both leak out of the membrane itself, though, and little protein pumps powered by ATP act to keep up with the leaking. I'm not sure how Na/K leave the brain or body.
     
  7. Monique

    Monique 4,700
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    It's because our common ancestor had already evolved these systems, you might like to read the following publication: Big ideas for small brains: what can psychiatry learn from worms, flies, bees and fish?
     
  8. fluidistic

    fluidistic 3,286
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    Ah ok I see. Now my mental picture of ions for neurons is the following: there are several ions floating around a neuron and they can penetrate via the ions channels of the neuron at particular times, when the channels open up. But how do the ions get to be around the neurons?
    ok thank you.
     
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