 Acetylcholine is a very common neurotransmitter, and I'm going to tell you a couple of places where we can see it. First of all, I'm going to tell you that this right here is acetylcholine, and we often abbreviate acetylcholine ACH. So if this molecule is acetylcholine, this molecule right here is actually nicotine, what? And perhaps you look at that and you're like, whatever, like, who cares? But there are some really interesting connections between acetylcholine and nicotine. Integration project topic would be really cool right here. So anything related to acetylcholine can be described with the adjective cholinergic. Cholinergic. So you can have cholinergic receptors, which are receptors for acetylcholine. If we wanted to call, let's just say we have cholinergic receptors, we do. There are actually two flavors of cholinergic receptors. You have nicotinic, oh, and muscarinic. Cool, nicotinic. What do you think would be true about a nicotinic acetylcholine receptor? Maybe perhaps nicotine might also act in their true story. So nicotinic, when acetylcholine connects to a nicotinic receptor, then it actually opens sodium channels and stimulates some sort of action potential in the whoever is receptoring. When a muscarinic, when acetylcholine binds to a muscarinic receptor, it's going to stimulate a second messenger cascade. We're going to open some G proteins and we're going to have a slower, more, we're going to have a different response. Where we have nicotinic and muscarinic receptors, and it's actually a form of fine-tuning the effects of acetylcholine. Are you ready for this one? All somatic motor neurons barf acetylcholine onto nicotinic receptors on skeletal muscles. Did you follow that? We're going to talk about that in more detail, I'll say it again. Nicotinic receptors are found on skeletal muscles and all somatic motor neurons barf acetylcholine onto those skeletal muscles at the synapse and the acetylcholine binds to nicotinic receptors on the skeletal muscle. Which is kind of cool. You wouldn't really think that. Acetylcholine, I'm going to draw you a picture of who's this guy? Chomp, chomp, chomp. This is an enzyme called acetylcholine esterase. Acetylcholine esterase. Ace means enzyme. So acetylcholine esterase breaks down acetylcholine and removes it from the synapse. This is important. And this is an interesting fast fact. You find acetylcholine all over the heck in place and it's involved in focused learning and the formation of new long-term memories. That's really interesting. All right. Acetylcholine, very important. We're coming back to it. Norepinephrine. This is another really important neurotransmitter. So let's talk about some facts of norepinephrine.