• Question: What elements is the brain made of?

    Asked by Ayrton to Ed, Kerrianne, Nina, Oli, yoyehudi on 14 Nov 2017.
    • Photo: anon

      anon answered on 14 Nov 2017:

      Its mostly water (so that’s hydrogen and oxygen), plus proteins, fats and some other stuff which is mostly carbon, plus more oxygen and hydrogen and a little nitrogen. There are lots of other elements too like phosphorous and calcium. There is a breakdown of the elemental composition by mass of the whole body here, which you might find interesting:


    • Photo: Oli Wilson

      Oli Wilson answered on 15 Nov 2017:

      ^^ That’s a really interesting diagram! Oxygen, carbon, hydrogen and nitrogen are really common in the body because they’re in all proteins, which are the building blocks of cells. I guess the calcium and phosphorus is mostly in your bones, so not much of that in the brain..!
      For what it’s worth, one of the rarest elements in the brain might be scandium – it exists in some parts of the brain at concentrations of 1.55 parts per billion. I say this only because I can’t improve on Theo’s answer, but I think the question’s really cool and want to answer it anyway 🙂

    • Photo: Ed Bracey

      Ed Bracey answered on 15 Nov 2017:

      There may not be a lot of calcium in the brain, but it’s super important!
      The reason your brain cells can conduct electrical signals is because there is a delicate balance of calcium, sodium and potassium and chloride ions in them.
      A brain cell is like a long, very thin bag of liquid.
      Imagine a very thin party balloon filled with salty water!
      Inside the cell, there are lots of negatively charged ions like chloride (Cl-).
      Outside the cell, there are more positive charged ions, like sodium (Na+).
      So the inside of the cell is more negatively charged compared to the outside.
      When a brain cell gets activated (say at one end of the balloon), positive calcium ions (Ca2+) rush into the cell through tiny little tubes in the cell membrane, called ion channels.
      This makes the inside of the cell more positively charged.
      That positive charge opens up other ion channels in the cell membrane, which are sensitive to the increase in positive charges.
      Those ion channels let sodium (Na+) ions in, making the cell even more positively charged.
      This opens up even more ion channels, creating a chain reaction that travels down the full length of the brain cell.
      This is how brain cells can act like little wires conducting electrical signals!
      The chain reaction is called an action potential.
      That’s a lot to take in, so here’s a video that might help explain it better:

      Brain cells use calcium in other ways too, to activate little protein machines that have special jobs in the cell, like increasing the number of ion channels in the cell membrane, making it more easy to activate.
      Magnesium is also super important for making memories – it’s a very important part of a special type of ion channel called an NMDA receptor, that can detect when two brain cells are activated at the same time and increase the strength of the electrical connection between the two of them.
      This is important because we form memories by changing how strong the connection between brain cells is.