You look at your car keys. You choose to pick them up.
Just like that – your arm reaches out and picks them up. Do you ever wonder – how does that work? How does the message get from your eyes to your brain and out to your arm? How does the electrical system of the body – the nerves – work that fast?
Every cell of the body is surrounded by a membrane. In the membrane is a sodium – potassium pump which actively pumps sodium ions to the outside of the cell and potassium ions to the inside of the cell – polarizing the cell. The result is – the inside of the cell is negatively charged with reference to the outside of the cell.
When a nerve cell receives an electric shock in one small area of the membrane, small gates in the cell membrane open and allow the sodium ions to rush into the nerve cell. This changes the charge in the inside of the cell from negative to positive – depolarizing the cell. This creates an electric stimulus in the next section of the nerve cell – depolarizing it. This wave of depolarization spreads quickly down the nerve cell, passing the electrical signal from the cell body to the end of the nerve.
There are two more important characteristics of a nerve cell. The nerve running from the spinal cord to the fingertip is one single, continuous cell. And the nerve cell has an insulation covering (myelin sheath) which has periodic constrictions called nodes. The wave of electrical discharge along the nerve does not have to move from one adjacent section of the nerve cell to the next, but can jump from node to node. This allows the electrical charge to move even more rapidly along the nerve cell. This passage of electrical current can happen from eyes to the brain, from the brain to the spinal cord, and from the spinal cord to the muscles of the fingers in microseconds – an amazing feat of engineering.
Even more amazing is the underlying complex system of lipids and proteins of the cell membrane, with hundreds of multiple reactions – which makes this complex system work so smoothly – and seem so simple (which you can review on Wikipedia/neuron). As a result, all the nerves of the body, working in this way, allow rapid and efficient communication between the various body parts and the brain.
Such a marvelous system, one of many in the body, was obviously the result of a knowledgeable Designer, don’t you think?
