 There's another way that the sympathetic nervous system can deliver its message to the whole body. And if you think about it, the sympathetic nervous system is responsible for your, oh, holy hell, something gnarly is about to happen. And if you don't rally physiologically, you are likely to be dead. So the bear is chasing you or the car is coming out into the intersection or go ahead and the chasing me bear idea is a little less scary to me than car accidents. And so that's probably why I use the bear analogy all the time, example all the time. But the faster and more effectively, you can deliver an oh shit response to every cell in your body, the better off or the more likely you are to survive. So that's where this whole adrenal sympathetic setup mechanism comes in. It involves the adrenal glands. The adrenal glands sit on top of the kidney. And if you were to slice an adrenal gland in half, you would see that it actually has an outer cortex and an inner medulla. And the cortex is actual endocrine tissue. And it's responsible for producing steroid hormones, like cortisol, like aldosterone. These are hormones that we'll be messing with later on in the semester, but they're produced by the actual endocrine tissue. The adrenal medulla, wait till you see what it actually is. This is wild. First of all, just like normal, just like you would expect. In this setup, we have a cell body, a sympathetic neuron. And here's the deal. I am not going to be able to draw this inside that adrenal medulla because you wouldn't be able to see it. But the preganglionic neuron synapses on basically a modified postganglionic neuron. All it is is a cell body. It doesn't have any axons. It does have receptors. And look at who the receptors are. It actually has both nicotinic and muscarinic receptors that respond to acetylcholine from the preganglionic neuron. The acetylcholine binds. And then this is, you think, dude, that's not a neuron, but it dumps who? I can't remember what color we made it. I think it was pink. It's going to dump epinephrine. Where's it going to dump it, you guys? Where would be a good place to dump it? I mean, there's no effector. It's not like sitting on, I mean, do you want to activate your kidneys so you can make a bunch of pee if you see the bear? I can definitely see value in that. How about we just dump that stuff right into the blood? Seriously? Who came up with this plan? Brilliant. So this little cell, which is in the adrenal medulla. So look, I'm going to draw it in here, even though you can't see it. This tissue in here is actually ganglionic tissue. These are post-ganglionic neuron heads, cell bodies inside the adrenal medulla. And all they do is dump epinephrine and norepinephrine into the bloodstream. Done. That's why when something terrible happens, like a car coming at you, you don't even realize that your body is flooded with adrenaline before you even have a conscious realization of what is happening and you're primed to do battle to whatever has scared the holy living tar out of you. I love that mechanism. I think that's really interesting. Then once this... We probably should keep it pink. Once the epinephrine gets into the bloodstream, then it can go out and holy mass messaging. That information is going to get out to all your different effectors. The last thing we're going to do in this lecture is we're going to look at a couple of examples of autonomic reflexes that are just a complete pathway from the stimulus all the way through. And there are actually things that we could mess with in the laboratory. Most of our things, we don't want to be messing with our blood pressure too much. We might a little bit. Maybe our osmolarity will mess with that a little bit too. Come pee pee lab time. But there's an interesting autonomic reflex that we can look at dealing with the pupils of your eyes and light. I'll be right back.