So humans and other large animals use electrical signals in our nerves to allow different parts of our bodies to communicate. But it seems like this is dependent on having nerve cells. Is electricity used other than in nerve cells? Do microscopic animals use electricity in their bodies? If not, what is the smallest animal to use electricity as part of its biological system? Are there any animals that don’t use electrical signaling? Are there any non-animals that do use electrical signaling instead of chemical methods?
Most of our cells use some kind of biochemical impulses that use differences in electrical potential. At those scales, ‘chemical’ and ‘electrical’ signalling are sort of the same thing.
I suspect maybe your mental model of how nerve impulses work is a bit off.
When a signal travels along nerve cells, it’s not like lightning. it works through ions passing across cell membranes. Usually ions of sodium and potassium for us, rather than bare electrons. These are electrical charged molecules, so depending on the concentration of ions inside or outside the cell, there can be a difference in electrical potential.
That ‘signal’ tells the nerve to release a neuro-transmitter (another chemical!) that reaches the next nerve and another set of sodium/potassium triggers, which sets off more reactions down the line. That’s why our nerve signalling is kind of slow - like 200-300mph slow, not fast like lightning.
And that’s not just nerve cells. Most of our cells get ‘triggered’ by this difference in electrical potential. For example, why do our muscles seem to lock up when exposed to electricity? Because muscle cells themselves are sensitive to those differences in electrical potential. Those differences in potential are controlled by the cell expelling or pulling in these charged ions.
Athletes often get advised to eat bananas or drinks with electrolytes (what muscles crave!) on hot days to avoid cramps, right? Well, that potassium helps with that part of things (those ions of sodium and potassium).
And it’s not just muscle and nerve cells. All our cells use these sorts of ion pumps to bring things inside and expel things outside. It’s all electro-chemical.
Is this true for plant cells and/or single-cell organisms?
Yeah, true for plants as well. Pretty much all cellular life.
The precise mechanism and chemicals won’t necessarily be the same but creating a difference of electrical potential across the cell membrane to open ion channels or pumps or similar holes is very similar across cellular life.
That’s the key.
Even normal boring non-biological chemistry is driven by electrical effects. Biochemistry is a very delicate balance of bioelectrical reactions between molecules, across membranes, and throughout and between cells and organs.
Pretty much everything a non-physicist thinks of, aside from a handful of things where gravity is relevant, is governed entirely by the electromagnetic force. All chemical processes are ultimately electromagnetic Even just an inert lump of rock is “using electricity”, in the sense that it’s electromagnetic forces holding it together.
We have TWO major systems to allow different parts of our bodies to communicate. We have a nervous system and we have an endocrine system. The nervous system uses electricity and the endocrine system uses hormones. I think things that are more important on a timescale of as little as a second rely on the nervous system, and things important on a minute or longer timescale rely on the endocrine system. There are a few things kind of on the border – for example the adrenaline rush you get a few seconds after being startled.
Shark researchers have found that sharks can locate prey by sensing the electromagnetic energy the prey’s muscles give off. I had some fishing lures made with little magnets on the body, and wee wires for legs. About that time, Parkinson’s Disease messed up my balance, and I had to give up boating and fishing. So, I never got to find out if my electromagnetic lures worked on freshwater fish.
My understanding is that all animal cells maintain some potential difference between the interior and exterior of the cell membrane, and at least some of proteins embedded in the cell membrane are “powered” by this potential difference. (And that the fancy stuff “excitable” cells like neurons do is an extension of the system that all cells have).
Bacterial flagellae are basically driven by electric motors.