 This is so exciting. I'm going to start out by telling you about the thymus because I really wanted to tell you about the thymus earlier and got rejected because the thymus is actually not an endocrine gland. The thymus is involved in mostly lymphatics. So it's involved in fluids. It's kind of like there's lymph node structures, it has some endocrine function related to the immune system. So it's like the immune system is the target of some hormones produced in the thymus and what part of the immune system there are lymphocytes in your blood and the thymus targets those lymphocytes with hormone to help them grow and develop so that they can be rock stars, rock star soldier warriors of the immune system. Awesome. Also, a structure that has endocrine function. We already talked about this one, the kidney. Remember how we said parathyroid hormone affects the kidney? Well, the kidney then produces a hormone called calcitriol and calcitriol is what goes to the digestive system and makes, initiates, reabsorption of calcium from the lumen of the digestive tubing. So you end up with more calcium. You increase the calcium in your blood, which is a valuable thing to do. Let's see who else do we have. Guys, dude, you remember this guy? We met this guy before with the digestive system. Pancreas. 99% of the pancreas is involved in the digestive system. 99% of the pancreas is exocrine gland. So it's dumping digestive juices into the lumen of the digestive tube and functioning in breaking down stuff, turning it less acidic, blah, blah, blah, whatever. Exocrine. 1% of pancreas cells are endocrine. And I'm going to just throw this little explanation up here because you're going to know the cells in the pancreas. You're going to recognize these guys. 1% of endocrine pancreas is found in the islets, the pancreatic islets, and you have two kinds of cells. You have alpha and beta cells in the pancreatic islets. And I have to, okay, alpha, one cells. You're going to remember this one because they produce insulin. Insulin, in fact, alpha cells in the pancreatic islets, they go Wonkarama. You don't produce insulin and you are diabetic. So you can either attack your own pancreatic islets and no longer produce insulin. Insulin helps you reabsorb glucose into your cells that are unique glucose to get energy. Beta cells produce a hormone called glucagon. Glucagon, it's not with an E on it, but I just thought, oh, glucagon, bye-bye, gone because beta cells take glucose. They actually know it's not gone. Never mind, I just totally, that analogy did not work anymore because it's wrong. So ignore that I even said any analogy at all. Instead, go glucagon must, if insulin decreases blood glucose by allowing the cells to absorb the glucose out of the blood, glucagon increases blood glucose by causing the liver to release glycogen into the blood supply, which if you're starving, you're going to be like, dude, glucagon to the rescue, liver, please give me some glucose from your glycogen supplies and your liver is like, sure, I got this, and barfs out a whole bunch of glucose for the rest of your cells. That was nice of your liver to share. Okay, pancreas, thymus, this one might be my favorite. Look, they didn't draw the heart in here, which I think is really interesting. Why? You got to have the heart. The thymus is superior to the heart. The thymus is found in the mediastinum, whereas the heart is in the pericardial cavity. This is so cool. I have to make it a new color because that's how cool it is. The heart has a group of cells in the right atrium that detects stretch, and if it gets too, if there's too much blood in the heart so that there's too much stretching happening, it produces a hormone called atrio, atrio peptin, peptin, and atrio, that was a cool little, I did that on purpose. The atrio peptin basically decreases blood pressure. When it detects stretch, that indicates that, oh, there's too much blood pressure. This is too crazy in here. Let's fix it. Atrio peptin says to the rest of the heart, dude, slow your roll. Don't contract so hard. Don't contract so fast. Let's lower this blood pressure. Oh my gosh, there's something else that the kidneys did that I forgot to tell you about. The kidneys make a substance called erythropoetin. Okay, I'll write that down here, but this is in kidney land. Erythropoetin, like that. Erythropoetin increases red blood cells. So if you go to, like, high altitude and there's a lower concentration of oxygen or a lower partial pressure of oxygen in the atmosphere, your kidneys are going to detect that and produce erythropoetin and say, dude, we need more red blood cells so that we can take advantage of this oxygen that we are missing. There's so many cool, I mean, this is physio, man. I love physio. It's just so interesting. Okay, stomach, I mean, here's my pancreas, so the stomach has to be over here somewhere. I'm just going to make you a list over here. The stomach produces a hormone called gastrin, which influences digestion. So when you have food in your belly, your gastrin is produced and you deal with it. And then, of course, these are all structures that only have pieces of them that do this endocrine work. We got our ovaries and our testes and our ovaries produce estrogen and progesterone and we'll do more of those. I mean, really, we're going to talk about a lot of these in more detail when we come to the body system that it deals with. Testes produce testosterone and when we get to the nervous, I mean, that's not nervous system. That's reproductive system. Don't get them confused. Sometimes they are confusing. Is that it? I told you everything, everything. Now, oh, you know I'm about to get really excited because now we're going to do an endocrine pathway. I'm going to show you what an endocrine pathway looks like in comparison to a nervous system pathway. And you know I love nervous system pathways if you are in my class. All right, endocrine pathways serving up in a second.