 I want to remind you about thyroid hormone and how this was one of the hormones that was regulated by the hypothalamus and the pituitary. So look at my cute little half-headed kid and remind yourself that this is the pituitary gland and this is the hypothalamus, just to orient you to where we're talking about. So this is just a blown up view of my little half head kid. Remind yourself that the hypothalamus is going to bust a move and produce a hormone called TRH or thyrotropin-releasing hormone. And remember that TRH from the hypothalamus was dumped into that portal system between the hypothalamus and anterior pituitary. And when hypothalamus says, whoa, we need some more metabolic action, dog pounds, TRH is delivered to ant pit. Ant pit says, I got this. I got just the thing, thyroid-stimulating hormone. Ant pit says, dude, let's dump thyroid-stimulating hormone into the blood. Thyroid-stimulating hormone heads to the thyroid gland, which increases the production and release of T3 and T4. Now, the question is, how does it do that? How does TSH actually increase thyroid hormone production? Are you ready for this? Here's a list. Number one, it increases the chopping rate of thyroglobulin. So remember our thyroglobulin had all those iodines on it and we were making it into T3 and T4. We increase the choppage, increase the number of enzymes that are going to cut that up and that will make more hormone. You can increase the rate at which iodine is absorbed into the colloid. So the more iodine you get, the more thyroid hormone you can produce. You can increase the rate at which thyroid, I mean, iodine is added to the thyroglobulin. So if you add the iodine faster, you can make more thyroid hormone. You can increase the size and activity of the thyroid cells. So all those cells surrounding the follicles, you're like, dude, we need you bigger, bigger, bigger. In fact, that's one of the reasons why if we have an overproduction of that message, the thyroid gland will actually grow. And along the same lines, we can just grow the number of thyroid cells, follicle cells. And if we make those, if we make more follicle cells, we're going to have a bigger thyroid gland. All of that will increase T3 and T4. Those are all things that you should be able to logic through and go, yeah, that makes sense that I would increase thyroid hormone. Now, the thyroid gland is involved in calcium homeostasis. There are lots of other things involved in calcium homeostasis as well. So we're going to look at an overview of calcium homeostasis. We're going to look at the bones and how that's involved. And then we're going to look at some of the hormones that are produced by the thyroid gland and by the parathyroid glands, which have you ever heard of those. And we'll see, spend the rest of the lecture talking about calcium.