Dr. Andy Galpin

So it's actually a fairly complicated milieu that go into it.

I'm actually still okay with you thinking about it as this modern mystery that has just this magical property where it contracts and causes electrical stimulation and action potentials out of nothing.

I'm cool with that too.

What we do know more about though is how this regulates the rest of your body.

So when we talk about skeletal muscle,

We know specifically there's a neurotransmitter called acetylcholine that is required for muscle activation.

So the reality of it is your nerves are actually not directly attached to skeletal muscle.

There's a little space in between them.

What happens is acetylcholine is on the presynaptic nerve.

So this is the nerve that comes in there.

It gets released into this little space in between.

actually attaches to little ligand gates on the muscle itself.

They open up, they let sodium into the tissue, and they cause a whole series of electrical things.

We call this an electrical to a chemical back to an electrical signal.

It's where you transfer an electrical signal down your nerves into a chemical signal back into an electrical signal that allows muscle contraction.

So once again, acetylcholine is the primary neurotransmitter that excites or activates skeletal muscle.

But shocking enough, if you put acetylcholine onto the heart, it slows it down.

Yeah, it does the exact opposite.

And so you have a number of nerves that are coming in.

Probably the most famous is the vagus nerve.