 Now we're going to look at the adrenal gland and the hormone path involved with this guy. So first of all, the hypothalamus and antpit are involved again. This time the hypothalamus is producing corticotropin releasing hormone, or CRH. That stimulates antpit to make adrenocorticotropin hormone. And that hormone acts on the adrenal gland and says, let's go ahead and produce some cortisol. Cortisol is a hormone that it's often referred to as the stress hormone. It is released as a result of stress. Technically, one of the consequences of cortisol, the whole idea of cortisol is to prime your body to react. Chronic cortisol production is not a good thing. It can be an immunosuppressant and an anti-inflammatory. Now think about, have you ever known anybody who's had a cortisone shot? Sometimes if your joints are super inflamed and painful, they'll actually inject cortisone, which is a form of cortisol, into your joint. And it's this steroid hormone that then acts as an anti-inflammatory. Reduces the inflammation and reduces your pain. It also, because it's kind of affecting inflammation or preventing inflammation, it's considered an immunosuppressive drug or whatever that is, chemical. When it's cortisone, it's a drug. So it can make you get sick more likely because it's telling your immune system, we don't need you to be reacting right now, which is why when people experience very stressful situations, they are more likely to get sick because their immune systems are weakened because of that. The other thing that I think is really interesting about cortisol is that it actually causes weight loss. Now, that might be counterintuitive to you because a lot of people in our culture, stress eat. And when we stress eat, we have stress, and then we self-medicate with food and sugar. And that will not cause you to lose weight no matter how much cortisol you are producing. So if you avoid stress eating, then the production of cortisol actually can cause weight loss. And if you think about super stressful times in your existence or someone you know, often you eat less and you start wasting away, like you can tell if somebody's lost a lot of weight, you get kind of worried about them. And that can often be a result of stress. Okay, so now you have the background of this whole system. Again, we see the exact same negative feedback mechanism. So we're going to use those mechanisms to figure out how to fill in this chart. So I'm going to tell you that I just told you that we're going to affect body weight. You agree with that because I just told you cortisol can cause you to lose weight. All of our reproductive organs aren't going to be affected by cortisol. The thymus gland, this is interesting. The thymus gland is actually representing our immune system in this simulation. And so you would expect an excess of cortisol to actually cause a decrease in the thymus gland. Now, our adrenal glands, are we going to have an effect of cortisol on our adrenal glands? You know we are. Is it going to affect the thyroid gland? No, it doesn't have an effect there. But is it going to affect our pituitary? Oh, show! Don't you even think about leaving Aunt Pitt out of the party? That's just going to get you in some deep trouble. You know what I mean. All right, so we have two hormones here. No, we have one, two, three hormones. But we're only adding two into our mix. Let's start out with cortisol because I think this one's a little more straightforward. All of a sudden, your rat is, like, doused with mad cortisol. We're not waiting for the adrenal gland to make it. Just cortisol. It's everywhere. My God, what's going on? Stress hormone. What do you expect is going to happen to the adrenal gland? Negative feedback. That cortisol that you just dunked in is going to tell the adrenal gland, dude, you please, please, we don't need you. Get smaller because there's massive amounts of cortisol. What's going to happen to Aunt Pitt? Aunt Pitt-y. It's bad. It's all bad. We need you to get smaller, Aunt Pitt-y, because this is just crazy talk, right? Negative. We don't need anymore. We keep adding more cortisol, but it keeps telling these guys, don't do anymore, please. What about the thymus? What are you going to expect is going to happen to the thymus? Dude, immunosuppressant. We would expect our thymus to get tiny. And what about body weight? Stress. As long as our rat doesn't stress eat, then cortisol, this excess amount of cortisol is actually going to cause our rat to lose weight. Now, you might be thinking, okay, how is this different than the adrenal corticotropic hormone produced by Aunt Pitt? So, sure, let's just go ahead. Massive amounts of this hormone, and we're adding it in itself. Ready? What's going to happen to... We're adding this hormone in. What's that going to do to the adrenal gland? The effect instantaneously on the adrenal gland is grow. Grow, my friend, adrenal gland. Grow, big, and prosper. I love you while you're growing. Right? Because that's its effect. We just keep adding more, and it keeps telling the adrenal gland to grow. Our grown-up adrenal gland keeps producing cortisol. Cortisol is going to feed back and say, stop producing adrenal gland, but adrenal corticotropic hormone trumps the negative feedback from cortisol. And so adrenal gland is getting huge. Cortisol is going to feed back still, and tell the Aunt Pitt, please don't produce any more adrenal corticotropic hormone. And Aunt Pitt's going to say, I got your back, man. I'm going to get as tiny as I can. It's not going to matter because some freak show is adding adrenal corticotropic hormone to the rat on its own. What were they thinking? So, where were we? We filled this whole thing out. We're doing this one now. We would expect, what would you expect to happen to the adrenal gland? That thing's going to get giant. What are you going to expect that's going to happen to Aunt Pitt? Aunt Pitt should decrease. What are you going to expect about the thymus? We have too much cortisol, so it's going to decrease. Body weight, too much cortisol, it's going to decrease. Do you see the one thing that we're going to look at to distinguish between these two? Are you excited to check out your rats? I hope so. Next one, the testes. A lecture is never complete unless you talk about the testes.