 Hi, team. Today's lecture, we're going to talk about the thyroid gland. And we're going to look at several different areas in which the thyroid gland, thyroid hormone function to maintain homeostasis in your body. Before we start, we kind of need to do a little bit of thyroid anatomy. This is gross anatomy of the thyroid, super gross. You can see the trachea here, you can see the larynx. The larynx, this in particular is the thyroid cartilage of the larynx, also known as the Adam's apple. If you find your Adam's apple, just inferior to that is where your thyroid gland would be. Now, the thyroid gland is kind of butterfly shaped and it kind of wraps around the back of the trachea as well. So, because we are going to be talking about some molecular mechanisms, how thyroid hormone is produced, we need to look at the histology of the thyroid gland. So, of course, we've got my favorite place, woof woof, to University of Michigan Rockstars out there with their awesome histology site. So, this is a microscope image of the thyroid gland. Now, I just want you to notice these amazing circular tubes that are essentially, they're surrounded by a really nice cuboidal, simple cuboidal epithelium and there's this kind of space inside. These are follicles inside the thyroid gland and I am going to draw you a picture of the lovely follicles of the thyroid gland. So, what I want you to remember, first of all, if we're going to be producing hormone, we've got to make sure that we've got a blood supply nearby and so all of our follicles are going to have a blood supply nearby. A follicle is literally a, hmm, I think I'm going with a purple follicle cell. It's a hollow ball of, whoa, you know that it doesn't actually go in there. It's going to be a hollow ball of cells and you notice that they were these cuboidal epithelial cells and I'm sure that I'm going to have to expand on this so I can show you what's happening inside but maybe I can actually fit it into this visual. This whole thing is a follicle. I've run out of room so I cannot continue the follicle and make it completely round, but it is. And the space in the center is filled with goop and it's called colloid. And there's actually really important functions that happen inside this and this space is where thyroid hormone is kind of put together. We definitely have some action happening in the cells but most of the big action happens in the colloid. So let's look at the mechanism for thyroid hormone synthesis and keep this picture, I think I can keep this picture and we can do it from her. All right, be right back.