Deprive the brain of oxygen and it dies in minutes.
Brain cells, as nearly all our cells, combine food with oxygen to generate energy. But brain cells need more energy than others. One out of five forkfuls of food is oxidized (“burned”) to generate energy for the brain.
The brain needs energy to recharge its cells, much as a battery needs energy from the wall to recharge. Stop recharging the battery in your phone and you’re soon out-of-service. Stop re-charging your brain cells, and …
Re-charging a battery or a brain cell involves moving charged particles from one part of the battery or cell to another. We move charged particles, rather haphazardly, when we doff a sparky sweater.
First, the sweater snatches electrons from our bodies. Electrons carry negative charge, so the sweater, with extra electrons, becomes negatively-charged; our bodies, having lost electrons, becomes the opposite: positively-charged.
Doff the sweater and the extra electrons on the sweater “feel” the body’s positive charge; they jump back to us, by the gazillions, in sparks.
When a sodium atom loses an electron, it becomes a positively-charged sodium ion. Brain cells move positively-charged sodium ions about when they recharge themselves.
A brain cell recharges by pumping sodium ions out of itself. When the brain cell fires – when it sends a signal to a muscle, or from one part of the brain to another – it opens portals that allow sodium ions to flood back in … and then begins pumping those sodium ions out once more, to ready itself to fire again.
Hundreds of billions of brain cells need lots of sodium ions. Carnivores obtain sodium from meat; herbivores, such as deer, from other sources, such as salt licks. So precious is salt, in ancient times was, it was used as money. Roman soldiers were paid in salt (“salt”, in Latin, is “sal”; those worth their salt received a salary).
Table salt – sodium chloride – is full of sodium ions. Problem is, the ions are locked tightly in the salt crystals.
We can loose the grasp of a crystal for its ions by heating it to the melting point … in the case of sodium chloride, to just under 1,500 degrees Fahrenheit … a bit warm.
Fortunately there’s an easier way to pull sodium atoms out of a crystal: Simply plop the salt in water.
Water molecules are not symmetrical; they have a positive end, and a negative end. When salt enters water, the negative ends of a dozen or so water molecules surround each positive sodium ion, tug on it, pull it out of the crystal.
One after another, sodium ions are pulled out of the crystal, until all are dissolved … and ready for use.
The ability of water to separate ions – at body temperature - has a lot to do with why water is essential to life.
Al Stahler’s science programs can be heard on alternate Tuesdays at noon on KVMR (89.5 FM). He teaches classes to students of all ages, visits classrooms, and may be reached at firstname.lastname@example.org