Whereas the electricity that powers our computers comes from the flow of electrons through a conductor and “hates” water, the electricity that runs our bodies is designed for a wet environment and uses pumped ions to help convey differing messages to our command center.
In this environment mere electrons are of little use because they would be easily dispersed. What is needed is something bigger. And as I eluded to in my opening an ion or ions will fit the bill. Well there just happen to be two atoms well suited for ionization- two atoms with 1 outer valence electron.
If we take a look at the Periodic Table
, and also a look at the electron shell
arrangement (note the sodium diagram on the right and also thepotassium arrangement
, we see these atoms are perfect fits for the job of positive ions (as both have only one outer valence electron).
Now we have the ions but we need a way for them to get into and out of the cell-> Ion Channels
Ion channels are proteins that line holes in the plasma membrane. They can open on demand to let ions in and out of the cell. They allow nerve impulses to travel, cause your heart to beat, and allow your muscles to contract. In many cells, channels and another kind of protein called a pump together maintain a relatively constant negative charge within your cells. This net negative charge, or membrane potential, affects the entry and exit of a variety of materials. page 15 of Bioinformatics, Genomics, and Proteomics: Getting the Big Picture
10 million to 100 million per second!
The importance of these precise structures and hence functioning of protein machines like these channels cannot be understated. Potassium channels, like other channels that pass other ions from one side of the cell membrane to the other, have a particular architecture that allows them to open and close upon command. We now know that intricately designed and mechanically fine-tuned ion channels determine the rhythm and allow an electrical impulse initiated when we stub our toe to be transmitted to the brain.- Ibid page 19
However even these, in comparison to electrons, huge ions also get lost in the wet environment. So what is needed are pumps along the way to pump ions in and also out. In the case of our nerve cells, ions go in to start the signal and are pumped out to reset that part of the system so it is ready for the next (or continuing) sensation. See nerve cell
(Some venoms and poisons effect these pumps (stop them from working) thereby shutting down the nervous system of the inflicted- ie paralysis sets in.)
However our nerves to not touch each other as wires do in an electrical system to make a circuit. Neurons have functional connections called synapses. These can connect neuron to neuron or other types of cells (for example muscle). Between the synapse and the next cell is a gap- the synaptic cleft.
This gap is too large for even ions to traverse. So to make the connection- to send the signal from one cell to the next, neurotransmitters
are sent. These flow in one direction. And once the neurotransmitters reach their destination, that cell responds accordingly, and all the neurotransmitters are dismantled and shuttled back to the transmitting site to be refabbed and ready for the next signal. (some do linger a bit longer and then disperse)
This is key because if the neurotransmitters stay docked the receiving cell would remain locked in that sensation. And if any unused neurotransmitters- the synaptic cleft is basically flooded to ensure signal transmission- remain they will just fill in the docking site when the first arrivals are gone. IOW the receiving cell will be locked in that past sensation.
And there are different types of neurotransmitters
for different sensations and purposes.
How is this evidence for ID?
The nervous system exhibits planning- it takes planning to get the right ions, ion channels, pumps and neurotransmitters.