 Hi, you guys. We're here for another lecture. Today's topic is bone organs. Last time we talked about bone tissue, cartilage tissue. Now we're going to look at what we can build with those kinds of tissues, and we're going to build bone organs. In lab today, we're going to look at all the bones in the body, all the bone organs in the body. First, we need to have some kind of perspective on what is a bone organ, like what makes up a bone organ. So, of course, in typical Wendy style, I have to draw you a picture. So I'm going to draw you a picture of a bone organ, and here it is, right about... Yeah. Oh, you're going to be so impressed with my bone organ. Pfft, right? Isn't it beautiful? Of course, there are specific areas of a long bone, which is what I've drawn for you here, and we're going to label those areas. First of all, the long straight shaft of a bone is called the diaphysis. Diaphysis. Then there is a magic medullary, not a medullary, an epiphyseal plate. What was just out of curiosity to see if y'all remember this? What was the epiphyseal? What kind of tissue was found in the epiphyseal plate? Rock stars, it was hyaline cartilage. Do you remember that? And the hyaline cartilage is the tissue that's found, so I'm going to color code all of this. This tissue is found in the epiphyseal plate. That's the structure, the epiphyseal plate. I'm telling you all of that because this area on my long bone is called the metaphysis. Metaphysis. So there's a metaphysis on each end of the long bone. And wouldn't you know it that at the top of the long bone, we're going to have one more name, and this one is the epiphysis, epiphysis. And there's an epiphysis at both ends. Found, okay, so we're going to look at all the tissues and we're going to look at all the structures, but the epiphysis, those are both the ends. The metaphysis contains the epiphyseal plate, but that's an area and the diaphysis is the shaft. And there are just other names for the parts of the long bone. Now let's look at some tissues that we're going to find in our long bone. We already have one place where we find hyaline cartilage and that's the epiphyseal plate, but hopefully we already know that epiphyseal plates, this is where lengthening of a bone occurs, but the epiphyseal plate closes and eventually gets taken over by bones. The epiphyseal plate is only present when you're growing. There's another use of what kind of tissue is this, hyaline cartilage, and so we use hyaline cartilage to also build a structure called articular cartilage. Articular cartilage. Articular cartilage is not a tissue type. That's the name of the structure. And articulation is a joint. So it makes perfect sense that you would put a cap of hyaline cartilage, because I made it blue, over the ends of our long bones so that we can articulate them or form a joint with another bone. Otherwise you wouldn't be moving anywhere. If your whole body was fused and there were no articulations, you would be a very interesting immobile person. So what other kind of tissues do you think we're going to have in our long bone? Well, hopefully, all around the edge here, what do you see? What do you think, what kind of tissue is this? Compact bone, my friends. Most bones have compact bone around the edges. And then what kind of bone is found on the inside? We actually, in, let's see, maybe I'll make it like, I'll make a little cavity space here. Because it's actually found, these are little, this is called a medullary cavity. Okay, so the structure is a medullary cavity. It's filled with different kinds of tissue. And one of the tissues that we're going to find in there is a spongy bone. Spongy bone trabeculae are found around and in the medullary cavity. And if we had a cross-section of a long bone, we'd be able to see the places where we would have compact bone, which is really hard and solid. And then spongy bone, which is more porous and exactly what you would expect. Also in the medullary cavity, we're going to have adipose tissue. There's a lot of fat in there. Now your, the medullary cavity contains bone marrow. So I'm going to make that also in parentheses because it has bone marrow inside it. So the cavity, does it work for you? The cavity is the space. It's filled with bone marrow. It's also filled with blood vessels, with nerves. It's also filled with adipose tissue and spongy bone tissue. And then it's filled with blood cell making tissue, which is hemopoietic tissue. So in addition to all of these other tissues, we have hemopoietic tissue. And this is the tissue that basically births blood cells. That's why in people who have leukemia, which is cancer of the blood, they actually have bone marrow transplants because the source of the blood cells is cancerous. So the problem is, so if you replace the bone marrow, you replace all that hemopoietic tissue and hopefully get rid of the cancer causing, like the funky guys in here who are going through mitosis too much. All right. Oh, what did we say last time that our entire bone organ was surrounded with? Bone tissue is surrounded on the outer edge by what? What kind of tissue is this? Dense irregular connective tissue. And dense irregular connective tissue, the structure that it forms, it's like a sock around the outside of my long bone, the structure that it forms is the periosteum. Now, think back. Remember, is it called the periosteum right here in like an adolescent human? No, why not? What's it called right there? Rock stars, it's the pericondrium right there, why? Because it's next to hyaline cartilage, right? Yes, of course. Can't tell the difference, it's the exact same structure with a different name depending on who it's sitting next to. We could probably come up with some interesting analogies for that, but perhaps we will not do that. I think that's everything that you need to know about the structure of a long bone. Now, we're going to look at, okay, what do they do? All these bones that we stick together in our skeleton, what is their function?