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Is there a visual demonstration I can see of approximately how "packed full of cells" the brain actually is? Yes. You can inject tracers in the CSF (Cerebrospinal fluid) or in the ventricles and monitor them. In this study, the authors have injected a fluorescent tracer in the CSF and used a direct imaging. We used in vivo two-photon imaging to ...


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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 high. The potential difference between the electrodes and impedance determines how much current flows, basically following Ohm's law: I = U/R. As to your ...


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http://en.wikipedia.org/wiki/Electromagnetic_pulse mentions the following natural sources of EMP, which I have ordered by frequency / period, from the shortest to the longest: Electrostatic discharge from objects coming into contact (normally too small to be of any concern) Lightning (milliseconds) Solar flares (hours.) Such flares cause geomagnetic storms ...


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By brain cells, I'll assume you mean neurons (the other type are called glial cells). Yes, new neurons arise in a least certain parts of the brain, and yes, they do cause memories to weaken or disappear. This has been shown in mice, guinea pigs and degus. It would be wrong to assume that neurogenesis occurs with the frequency of, say, gastric cell or skin ...


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$H_2S$ is the end product of sulfur related respirations (like sulfate respiration, sulfur respiration, etc...). By aerob (oxygen) respiration the oxygen in $O_2$ has 0 oxidation number, by $CO_2$ the oxygen has -2 oxidation number, so it was reduced while the carbon was oxidized. By the thiosulfate respiration of Salmonella enterica the following reaction ...


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Current flow is the movement of charged particles (ions in this case). The membrane potential is the charge difference across the cell membrane. Usually there is more negative charge inside the cell than out, so the membrane potential is said to be negative. When ion channels open, typically positive ions (Na+, K+) will flow into the cell as they are flowing ...


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I believe every living organism (even single cell ones) experience pain somehow, because it is important to stay alive. The scientific answer depends on how you define pain... Related articles: Evidence suggests that some, if not all, invertebrates have the potential to suffer through current practices that do not take into consideration that ...


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The brain is not an electronic device. An EMP is basically a large amount of electrons flying by all at once. They are negatively charged, and as they pass by they distort your local EM-field (hence the name). This distortion induces current in the wires (a phenomenon known since Faraday) - since most wires aren't made with a large tolerance, the sudden ...


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The answer can be found in PubChem, which is linked in the comment by anongoodnurse. I would not say that Norepinephrine is beta2 adrenomimetic because norepinephrine has many roles such as neurotransmitter. I would just say that Norepinephrine is alpha, beta adrenoagonist. More pieces of information about it from PubChem:


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Addition to anongoodnurse's answer. Different organisms have different numbers of neurogenic niches (regions where neurons form). For example zebrafish has six niches compared to two in mammals and it is known to have active neurogenesis throughout life. In mammals, apart from the dentate gyrus (subgranular zone) of hippocampus, the other prominent ...


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I am colorblind, but I did not know that before I was 22 (!!). I got to know it by doing the Ishihara test. There are other tests you can do to test for colorblindness, such as the reverse colorblindness test (http://www.cs.unm.edu/~aaron/creative/colorTest.htm), where a "normal vision" person will not see the two patterns shown there. Anyway, there is no ...


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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 ion diffusion, but as an electric field"? A: Capacitance basically results in sequestering of charge of opposite polarities along the cell membrane, which ...


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The Hodgkin-Huxley model: $$I=C_m\frac{dV}{dt} + g_k(V_m - V_k) + g_{Na}(V_m - V_{Na}) + g_l(V_m- V_l)$$ Where $C_m$ is membrane capacitance per unit area and $g_i$ are membrane conductances. Reducing the number of channels does not affect capacitance per se (it does in a way) but what it basically does is to reduce membrane conductance to leak channels ...


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First the boring (but most important part) looking at the study: It is important to critique the study design FIRST to see what kind of information we can actually obtain from this study. This is a meta-analysis of cross-sectional studies (meaning there is no record of change over time) that include a variety of age ranges of ADHD patients (some on ...



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