Okay, all of the following, oh Angel you can open it, all of the following apply to both ossifications except. So let's just go through them and talk about each one. What forms bone? What cells?
So is that one true? Okay, what bone is every time except for this exception we haven't learned yet, what is produced first? So is that one true?
Okay, both processes, intramembranous and endochondral, they both start with mesenchyme. What do y'all think? Yeah, they both use cartilage.
Which one uses cartilage? Endochondral only. So which answer, all of the following apply to both except which one? You got it.
Okay, so the next is just another. version of intramembranous ossification. So we have four steps.
Of those four steps, what is the first step? So what do we need to make if we're going to produce an ossification center? So we need osteoblasts.
And what do osteoblasts produce? Which is the matrix. okay and there's also going to be some fibers in there okay so that would be b now once we make the bone what needs to happen to that bone yeah it needs to get hard which is d so b then d so boy then dog okay then what type of bone do we form first so what's that one and then once the spongy bones formed we're going to form compact bone and what's finally going to form around the outside How many layers? Okay, so it's B, D, C, A. Okay, so I just passed out an exercise to the table.
So if you have two big groups at your table, you have two. If you have one, two small groups, you're combining today. Yep, Stephanie, scooch over.
And you're going to do this. This is the same thing y'all did yesterday or Tuesday, except for this one is endochondral ossification. So it's the same process. You get pictures, you get words. It's not from Wiley.
It's from a different publisher. So it makes you think a little differently about the process. Ahem. You ready? Let me check.
Okay. Okay. All but two are right. The order of the pictures are right, okay, but there's a key word here, cavitation. What does that sound like we're building?
Okay, so look at these two pictures. Where do you start to see a cavity start to form? You got it.
So they get swamped. That make sense now? Yeah.
Okay, and the thing is, is this is not exactly how I taught it, but it's taking the knowledge you have and applying it to a new scenario. The steps are the same, it's just different terminology from different textbooks. Very close, you missed one. Y'all ready? Yep.
Okay, so basically everything is right except for one of them. Look at these two pictures. Which picture do you see kind of a cavity starting to form? Oh wait, sorry.
I think I got it right. I read color as cavitations. I need more sleep, y'all.
Y'all have it right. Okay. Probably.
I can knock out chapter nine really quickly. Just cut out all the fun stuff because we have to cover stuff. Okay, good job.
Which way am I going? This way or this way? Okay. Cavitation basically means creating a cavity.
So which one looks like you're creating a cavity out of these two? Wait, why not? Yeah, it's deteriorating.
That's a cavity that's being formed. Okay. So our words are right?
Everything's right. Oh, I thought our words were wrong. No, that's what I was saying.
So if you look at this, so this is the same process that we went over, but different terminology because it's a different textbook. So this means that you're using your knowledge of understanding the foundation and trying to figure out how they're explaining it. Same process, they're just different terms.
That's why I like pulling different publisher stuff. Good job. Y'all ready?
Y'all got it. Good job. Okay.
Oh, I didn't? I'm sorry. My two-for-group. Sometimes y'all have them, sometimes y'all don't. I know that Ha has a surgery today, or yesterday.
Yes, good job. Okay. Okay, so now y'all are going to be able to be the teacher. Y'all get the Expo markers. How much fun.
And y'all get whiteboards. Okay, so what we're going to do is we only have six boards in here. And if you look, we have five tables.
So basically, y'all are just going to split up. I don't really care who's in what group, but you don't want 12 people in one group. Some of y'all are going to go to one side of the board.
The others are going to go to the other side. So we have six boards kind of split up. You can stay partially with your group.
You can stay with your group. We just need to split up to a group that's on each side of the boards. On each of the holders, there's four Sharpies or four Expo markers. Each group, just grab two.
This purple one does not work, so ignore this purple one. Y'all are going to recreate this chart without your notes with your group and try to fill it in. So y'all come on up here.
You don't have to redraw the whole chart. As long as you keep everything in the columns, I'll know what y'all are doing. So no books, no notes.
You got each other's brains to work with. Go to each side of a board. Y'all can form your own groups.
Try not to look at your other teams. Try to be internally honest. It's up to you. It's just that there's more people than boards.
Just join. You can stay with your group, Ashley, or you can join someone else's just because we don't have as many boards as people. So you can either stay with your group or you can just hop into another group. And y'all can share the writing because it's so much fun to write. If y'all need more markers, I have a whole bag.
Isn't it kind of fun writing with Expo Peds? Hey, y'all, there's no one on this side of the board. So a few of y'all that are hanging in the back want to come work as a group.
Come on, y'all. Some of y'all need to come over here. I'm gonna nominate y'all, y'all three to go to the other side.
Ashley, you're gonna join them for the other side just because that board is not getting any love. Look at you, taking a picture so you don't have to look around. Angel if you want to switch off one of the light switches that it just take the glare off the TV.
Yeah, that's better Either, either, either, either. Either is fine. Uh-huh. So, intramembranous comes from what germ tissue? Intramembranous comes from what embryonic connective tissue?
Intramembranous comes from what major tissue? Where does it occur in the body? What's the timeline for it? Make sense?
Okay. Which one are you stuck on? Don't overthink it.
It is connective. What type of connective? It's the same answer as the one above it. because it's going directly from it. So it's never actually forming a mature connective tissue until it forms the bones.
I'm doing okay? I like all other. As long as y'all know what you're saying, it's good.
Even further, so this is going to be basically young adulthood. So I would say like late teens, early 20s. 18 to 21. I mean, we have to just throw out an age number there. I mean, it can go up to 25 depending on the person, you know what I mean?
Yeah, some people don't fully stop growing, especially, have you ever seen extra tall people? They actually have an extreme issue because when they grow that much and that fast, it really affects their bones. So they'll actually take hormones to close their plates. Yeah, because it's so dangerous to them because it really affects their joints. They can't handle the pressure, the weight and everything.
Okay, that's good. Y'all good? Y'all done?
Y'all want me to look? When does this end? So that one has the ending. When does this one begin?
And then when does this one end? That's when it starts, for this one. So when does this one end and then when does that one start also?
It's not dense irregular, but mesenchyme looks just like dense irregular, so it's really just mesenchyme. Yeah, but dense irregular and mesenchyme look exactly alike. They just have different functions in the body.
Where? Like what bones is forming? Okay, so this turns directly into what? Osteoblasts.
What, before osteoblasts? Osteoblasts. Those are cells.
So what tissue is this? Embryonic tissue. It's embryonic tissue.
It's mesenchymal. tissue forms the same thing. I would say mesenchymal. Yeah, because we're not turning into an adult tissue until we go into bone. So this goes directly into bone.
This one has a little in-between step. Okay. intramembranous, endochondral.
What does the chondro tell you? Okay, so you got it. Okay, and what type of cartilage be specific? Okay, you got it. Okay, and then this is telling you where in the body, which bones, and this is just tight line.
Age here, what bones in the body here? Well, remember how we talked very specific about where these occur? anywhere else yeah okay you got it pretty much technically technically okay so not birth of this product because this starts happening in the womb oh yeah remember the timeline but what time yep So six weeks to what? Not born yet.
Six weeks in the fetus. About what? Early at 11. You got it. Okay.
This one starts in the womb. So when is it going to start? Same time as this. Six to seven weeks.
Okay. Okay, and don't worry about the tissue. We'll talk about that as a group. Okay. Okay, so y'all can come sit down once you're done.
I will ask y'all to erase these for me in a minute. You don't have to do it right now. Okay, so y'all have this table in the packet I passed out yesterday or Tuesday. It's dropping down. So let's just make sure we fill it out.
I checked everyone's. It was great. So this is just a great way to compare contrast on the test. you're going to get a lot of questions and it's not necessarily that they're that high level skill questions it's more do you know your facts so you can apply them or compare them so germ tissue what runs the germ so which do these both come from okay embryonic connective tissue Is that for one or both?
Okay, when you hear the word endochondral, what does chondro tell you? So the mesenchyme is going to turn into what tissue? Say it with confidence.
Okay, now for intramembranous, does mesenchyme actually turn into another tissue before it turns into bone? In intramembranous, it's inside a membrane, and membranes are just sheets of tissue. So we start off as mesenchyme, and mesenchyme turns directly into what?
What is it going to turn directly into? What are we making? Bone. So there's no in-between tissue.
So the tissue that is starting out as is the mesenchyme tissue. Now, mesenchyme tissue is going to form what type of cells? Osteogenic or osteoprogenitor.
And then from osteogenic, what do we form? And then the blasts are going to build what for us? The matrix. And the matrix is, what are we building?
What's the whole goal of this? We're building bone, okay? So y'all have to be really careful. When it asks for tissues, are cells tissues? No, cells make up tissue.
But if it asks for a tissue, we're looking for a tissue name. If it asks for cells, then we're looking for genic, progenitor, blast, class, site. So always make sure you read those questions because the key words are there, and that helps you eliminate possible choices. Okay, where in the body does intramembranous occur? Everyone agree?
I'm just gonna put the jaw short of the right. Okay, where does endochondral occur? Basically is neck down kind of a safe way to say it? Is that technically perfectly correct? No, but it's the easiest way to kind of describe it.
Okay, both of these start around when in the womb? Yeah, approximately six to seven weeks. I don't know how well y'all can see that light green. Sorry about that. Okay, so they both start about the same time.
Intramembranous is basically... Yes, your skull. So when does that usually complete? Right before puberty ish, basically late adolescence. And then endocondrial, when do we basically stop growing?
Yeah, late teens, early 20s. Is everyone unique? Yeah, so that's basically they took a million people. They did it. That's the average age.
So some people might stop at 15. Some might stop at 25, but they just did an average age. So we just usually say late teens, early 20s. Okay, so I got a bunch of clicker questions.
So go ahead and grab your clickers. And then we're going to start new content. Hold on, let me get this started. This is a fluff question, meaning you've got to figure out what it's asking.
There's a lot of fluff in this question. i'm gonna give you about 15 more seconds they're missing two people one person okay So let's look at this question. Remember I said there's a lot of fluff in this question?
Hey, this means nothing to us. This word is just talking about this fluff. So really all it's saying is endochondral ossification makes bone from a template made of what?
Hyaline. What does endo tell you? Within and what does chondro tell you? Cartilage. So how many of y'all remember taking tests in elementary and high school?
I don't know what they're called anymore, like leap tests or whatever they are. And reading comprehension was on there. Yeah, it's tough because you're like, what's important in this paragraph?
You just got to read through it, underline important words. That's why I allow y'all to write on tests. Okay, keep going. Let me get started. Bless you.
Bless you. I like that sound the clickers being put down. Y'all got this. They're missing just a few people. One person.
Okay, most bones of the skull. How are most bones of the skull formed? Intramembranous.
Okay, how are most bones of the body formed? Have we talked about A, B, or E yet? No, that's what we're going to cover soon.
Okay. I'm missing just a few people. Get that answer in.
Okay. Now, before we talk about the answer, I want to go over how to dissect this question. Okay. First major word in there, and there's quite a few you can start with.
I'm going to start with cartilage model. If it's cartilage, is it endochondral or intramembranous? Okay.
Endochondral is going to form most bones of the body. Are most bones in the body going to be flat bones, short bones, long bones? Okay.
So that's another key word here. And then when we talked about long bones, we talked about the six steps. Again, I don't care if you did it in six steps.
You can tell it to me in 20 steps, one long step. But when we're forming the long bone, we're forming the basic parts of the bone. What are the ends called? and what's the shaft called?
Which one do we form first? So this is going to be your primary and then what is the secondary? Okay so what's this answer? You got it.
See I'll kind of see how I write questions to make you think. Okay. Okay, here you go. I'm just missing a few of y'all.
Okay, lots of words that we can look at here. I'm looking at first type of bone and compact. What is the first type of bone that usually forms? Usually always spongy.
So what would that make? It would make it false. Okay.
So the next part is we've talked about how we develop bones. So these are just telling you some cool animations in Wiley, bone formation, bone growth, and remodeling. Now we're going to talk about how bones actually grow.
So we've developed the models whether it's through intramembranous or through endochondral. Remember when we're a fetus where it's really tiny and then over time we grow. Once the baby comes out over time what does the baby do? It keeps growing. So your bones have to grow to accommodate the growth of the child.
So there's two different ways that we grow in the body. We grow not only in length, but what else do we grow? And think about trees. We grow in width.
Okay. Growth in length is known as interstitial growth. Where do we know we grow in length? Epiphyseal plate, and that is only found in what type of bone shape?
Okay. What's the easier term for the epiphyseal plate? Well, the lines once we're stopped growing.
Growth plate. Okay, epiphyseal plate's the long word. Growth plate is the easier word. And that's only found in what shape of bones?
Okay. Do we grow in height and length throughout our entire life? No, just throw out an age approximately when we stop. 20 is fine, yeah. 18. Again, remember, everyone's a little different.
Okay, now, that's growth in length. The other type of growth is going to be growth in width, and that is known as appositional growth. Appositional growth occurs in all bones of the body and it occurs throughout life. Okay, you want to know a silly trick to remember the difference? It's really silly.
Okay, when you think about apples, are apples tall or are they wide? Okay, so appositional basically is an apple. That's growth in width. You see the first letter in interstitial?
It's a very tall I. Interstitial growth is growth in and length, so getting taller. Okay, so we're going to start off with interstitial growth. Okay, interstitial growth is growth in what? In growth and length.
Where does it occur? Growth plate. What's the fancy word for growth plate?
Epiphyseal plate. Okay, here's a little, let's think back to when we first started this chapter last week. Epiphyseal plates. located where in the long bone in the metathesis so the epiphyseal plate is where a growth interstitial growth occurs only in long bones specifically the metathesis Y'all remember what tissue it's made up of? The most common tissue, common cartilage in the body, hyaline cartilage.
So your plate is made up of hyaline cartilage. Now, there's actually four zones of hyaline cartilage. Each of these zones has a name, and the name tells you what's going on in those zones.
So when we're looking at this picture, this is something you have to do in labs, have to recognize them. But when we look at this picture, does this area look a little different from this area? Okay, it's still all hyaline cartilage. but different events are occurring in those areas which is going to help your bone grow in length.
Okay so when we talk about this we're going to talk about the first zone. The first zone is known as resting cartilage. Sorry who's ever masterpiece I am erasing. Okay, so let me just draw this bone out real quickly here.
Okay, now what do we call the shaft of the bone? What do we call the ends? Y'all will get it. Okay, how many zones do we have in the plate? How many plates do we actually have?
Okay, these are just very big plates. Okay, our first zone is zone of resting. Notice I am writing the zone of resting closer to the epiphysis or the diaphysis. Okay, your zone of resting helps secure the plate to the epiphysis. The zone of resting helps secure the plate to the epiphysis.
When you hear that word resting, remember this is your body. Does anything actually ever rest in your body? No, even if it's, bless you, even if it's not actively dividing or growing, we're still having metabolism, so chemical reactions still occur. So the zone of resting, it's actually just prepping for division.
Nothing's actually happening except for prep work. okay next zone is the proliferative zone i just told you i'll don't use the purple that is the one i grabbed okay you know what the word proliferative means we learned that when we talked about epithelia tissue what does proliferate mean to what i'm sorry to regenerate what's another word that we learned about that it's not just regenerating it's actually doing what dividing okay proliferation is active cell division it's really just rapid mitosis so resting we prep proliferation we divide next zone is your hypertrophic zone. This is another word you already learned.
What does hypertrophy mean? Growth in what? Say it loud.
Growth in size. Hyper, a lot, trophy, growth. So basically we're just getting big. In this zone the cells get large.
but they lose the ability to divide. So the cells do get bigger, but they cannot divide anymore. Do y'all remember I handed y'all out toys that day to demonstrate Piper Trophy?
What did I hand out? The balloons. Okay, we're not making more balloons, that one balloon just gets bigger. And then the last zone is calcified.
What do we think calcified sounds like? Calcium! And what do we find calcium in? What type of tissue? Compact what?
We find it in bone. Okay, so the zone of calcification is when we're actually making new bone. Okay, so let's talk a little bit about this though.
All I've been saying is cells. I haven't talked about what type. These zones are made up of what type of tissue?
Highland cartilage. What cells maintain cartilage? Okay, so when we talk about these, we're talking about chondrocytes.
chondrocytes prep for division chondrocytes divide chondrocytes get larger in size so chondrocytes prep chondrocytes divide chondrocytes grow in size but what's our whole goal we're using cartilage to make what tissue yeah to make the bone So in the calcified layer, chondrocytes are going to die because bone's replacing the cartilage. So those poor chondrocytes do all the work. Bone gets all the glory.
The calcified zone. Yes. So basically they just die.
they've done their job but our whole goal is to make bone so if chondrocytes are dying what cell has to actually make the bone osteoblast so in the calcified zone the chondrocytes die osteoblasts produce bone so they're making that matrix but we got to clean up some of this cartilage so we have this cartilage that was present we're starting to replace it with bone but we have to clean up leftover cartilage what bone cell can help us clean okay so at the same time that chondrocytes are dying osteoblasts are making bone osteoclasts are doing some cleaning up So your body does not depend on one mechanism. Your body uses a lot of different cells to work together for your final product. So when we're making new bone, are we adding new bone to the epiphysis region or the diaphysis region? Because this is where your bone is being made, in the calcified region.
So we always add new bone to the diaphysial sides. So basically when your long bones are growing, they're growing, they're pushing out. So the ends get pushed out just like this. It's happening at approximately the same time. Usually you're this is not something you need to write down but usually your proximal epiphyses are your proximal epiphyseal plates so those are the ones closer to your torso those usually close a little bit earlier than your distal ones so if we're looking at my humerus is this my proximal or my distal then this would be my here's my radius and ulna is this my proximal or distal epiphyse um and then this would be my Usually the proximal closed just a little bit earlier.
Doesn't mean it has to, it's just usually if you look at a lot of different stats, the proximals close a little bit earlier. Okay, now this is going to occur until you hit, you know, late teens. Eventually osteoblasts are going to lay down bone throughout every single layer. Once we lay down bone, we lose that plate. At that point, what do we call it?
the epiphyseal line. So if you get x-rays and you have a plate, do you still have a chance to grow? If you get an x-ray and you have a line, yep, you're not going anywhere. You're the same height.
So when we look at this picture right here, let me just go to a bigger version of it. Okay, you'll see this space. Okay, here's your epiphysis.
There's the diaphysis. This area is your metathesis. Y'all see how there's a big old space right there? That's cartilage. If we have cartilage present, are we growing or are we stopped?
Okay, we're growing. Okay, so both of these, what it's just showing your knee, your femur, and your, so this area here where there's a space, that's your femurs, distal epiphyseal plate. Here's your tibias.
do y'all know the bone beside your tibia the fibula so do y'all see these spaces between it all those spaces between our plates cartilage doesn't take x-rays very well so that's why it always just looks like a black spot okay now let's see what it looks like once it closes okay here do y'all see a space between that bone do y'all see a space right here though So when you tell me one or two, which one still has growth left? Okay. So this one is still someone growing.
So we have plates. What about this one? Do we see any plates?
So they have stopped growing. And what's instead of a plate, what do we have? So now we have a line. Now we have to think about homeostasis.
I'm going to go back to the picture previous to this one, just this picture. If we are having 10 million chondrocytes die a day, and this is in your prime growth period, so say that's around early teens, 12, 13, if we are having about 10 million chondrocytes die a day, approximately how many should we be making a day? Not twice, but let's just think homeostasis. Homeostasis is equal, the same amount.
So old chondrocytes are replaced by bone. The same number that are replaced by bone, what are we making? New chondrocytes.
Now eventually, do you stop growing in length? So eventually we're going to keep replacing chondrocytes with bone, and what are we going to stop producing? we're going to stop producing them okay and that's going to be towards the end of your growth okay so as soon as you stop producing chondrocytes that means your growing days are ended okay have you ever heard people say i broke my um growth plate it's super common in kids especially kids that play sports what are sports that use your arm a lot baseball especially pitchers tennis any sport that's using arms to have a lot of force very likely that you can actually tear your epiphyseal plate if you break your epiphyseal plate do you think it could potentially affect your growth yeah I definitely can okay so you don't need to write any of these down these are just showing you different types of fractures You can see some of them are showing you directly through the epiphyseal plate.
Others are showing you different types. What I want you to do is I want you to look at the top fractures, the types, and I want you to look at this picture. Don't blurt it out.
I want you to see if you can figure out what type of fracture it is. And this might help you out, so let me show you some stuff in here. Tell me what to label.
Okay. this is your tibia right here okay this right here is your plate what part of the tibia is this that's the epiphysis okay this is going to be what then the diaphysis or what we can see of it and then the plate's going to be in what region okay so that may help you try to look at what's going on here versus the types. This is what radiologists get to do.
Take your kid to the doctor. They break something. They show you the x-ray. Does anyone think they have an idea which one it is? Anyone want to raise their hand?
Okay, then let's talk through this. Right here is your plate. Do y'all see how this is not solid going that way anymore?
Can y'all see that gap over there in the epiphysis? Can y'all see this right here? Okay.
That's a break. The break's in the epiphysis or the diaphysis. Okay, so now let's look up here. For type 1, where's the break? In the growth plate.
In type 2, it's in the growth plate, but what else is it in? In the diaphysis. In type 4, it's through the epiphysis, the plate, and the diaphysis. And type five is just crushing it. Basically, we're smooshing it.
But look, type three, it's breaking part of the plate and it's going through what part? The epiphysis. So what would you tell me this is? This is a type three.
Okay. Now, since we can still see the plate, is this someone that's going to be growing or someone that's not going to grow? Yeah, they're still growing.
Okay, so for any question that you see about growth and length, interstitial growth, one of the most important things is to pay attention to age. If I tell you a 13 year old breaks their epiphyseal plate, regardless if this is bad break or a good break, or is that person still growing? What if I told you about 27 year old broke their epiphyseal area? No growth.
So And what if I told you a 22 year old broke their epiphyseal plate? There's still potential for growth, probably not much. If I said someone damaged their epiphyseal line, it doesn't affect their growth.
So you just got to really pay attention to the words and the age given. Okay, so lots of things affect growth. Hormones are the biggest factor. There's I'm just gonna go over three hormones quickly.
Okay, IGFs Thyroid and sex hormones. Those are the three groups. I'm gonna go over super quickly and I'm gonna go back to a different picture Okay, this is just a drawing y'all. Okay What is that little gland that hangs down from your brain? Okay, so this is such a bad picture.
Okay, okay. So there's your pituitary gland. Your pituitary gland releases growth hormone.
Have you heard of growth hormone? Human growth hormone, bovine growth hormone, growth hormone. Okay, so it kind of looks like a chicken. So what was going to happen is the pituitary gland is going to release HGH, which is growth hormone.
HGH is going to target the liver. Your liver is going to release. something called IGFs.
IGFs stands for insulin growth factors. So your pituitary gland releases growth hormone. Growth hormones release into your blood.
So is that endocrine or exocrine? So it travels in your blood to your liver. Once it hits your liver, it tells your liver to release what?
IGFs. Now IGFs are really important for growth in length. IGFs are going to target two major cells.
They're going to target chondrocytes and osteoblasts. IGFs are going to target chondrocytes and osteoblast. Okay, now when they target chondrocytes, they're telling chondrocytes to divide.
What specific zone does IGF target? The proliferation zone. IGFs.
So it targets chondrocytes and says divide. So it's specifically targeting that proliferative zone. But remember, I also said it targets osteoblasts.
In what zone are osteoblasts active? The calcification zone. So IGFs are telling your bone, let's grow in length and let's make new bone. So it's kind of doing a double job.
It's saying chondrocytes, let's add length. Osteoblasts, let's add bone. Now you start producing a lot more growth hormone when you hit around puberty.
And what usually happens around puberty? It's your first major what? but first major growth spurt so we produce more hgh around puberty hgh is targeting igfs and igfs target the plate so what's happening is we're seeing an increase of growth when we're producing more hormones okay thyroid gland what's thyroid glands what are they targeting Stop there.
They're targeting osteoblasts. What do osteoblasts help us produce? They help us make bone.
If we're really targeting osteoblasts, what zone are we targeting? The calcified zone. And then sex hormones. What are the two major sex hormones? What do females produce the most of?
Okay, and what do males produce the most of? Do males produce any estrogen? Do females produce any testosterone? Okay, so we have these two hormones. You produce them from birth, but really large amounts when you hit puberty.
Okay, estrogen targets, and we're really concentrating on estrogen because this is the one that does most of the work. for you, males and females. Estrogen targets osteoblasts.
So it is telling osteoblasts to make more bone. So what zone is it targeting? The calcified.
So right when we get that huge increase of estrogen around puberty is when we get our huge growth spark because it's activating those osteoblasts. But as we get older, Even in your late teens, the amount of estrogen you're producing just drops just a little bit. But that drop in estrogen production also tells your plate to do what? What does it say up there?
Clothes. So estrogen is really important in that initial growth, and it's important in stopping the growth. Everything that's affecting osteoblasts is affecting the calcified zone.
So remember hormones are released in the blood, that blood's traveling around your body. and the blood travels to your bone. So it's the hormones in the bone, I mean the blood, that are affecting the cells.
Now estrogen also has another factor. It's telling osteoblasts to increase production. It also tells osteoclasts to slow down a little bit.
So are we building or breaking down more? we're building more and that's really important because that way we build a tiny bit more bone than we're breaking down what happens to females at menopause what do they stop producing as much of they stop producing a lot of estrogen which means we're not promoting bone building and we're not stopping bone breaking down that means osteoclasts kind of get to do what they want which means what are they going to do to our bone what do osteoclasts do they break down bone. If they're breaking down a lot of bone, what's going to eventually happen to your bones? They get weak, they get brittle.
What's that disease? That's why it's super important for females especially to watch their diet and exercise because once you hit a certain age, you don't make as much estrogen which means you're not building as much bone, you're breaking down a little bit more. So the more bone you break down, the weaker your bones Okay, so this is just kind of a picture to show you. Let me get all this ink off.
Okay, this picture is just showing you basically what we just went over. There's your pituitary gland. It's going to release HGH. HGH is going to target which organ? The liver.
So you see this line to the liver? The liver is going to release what? IGFs. And IGFs are going to target what type of cells? Chondrocytes and osteoblasts.
So this is just kind of showing you the pathway. Now when you hear that word growth hormone, what do you think growth hormone actually does? It causes things to do what?
Grow. Growth hormone affects every cell in your body. This chapter is focused on bones though.
So we were only looking at the bone effects. Okay, now grab those clickers. I'm missing seven people. Okay, so it's asking...
which type of cells proliferate and then become calcified? So what cells are doing the division? And then what cells basically die because they're becoming calcified?
So the answer is chondrocytes. Missing eight of y'all. Get them in.
Stopping it in seven seconds. Okay, which zone does do chondrocytes divide? Proliferative.
So the answer is B. Okay. Missing one person.
Okay. What is the answer? Because the key here is increase in size, but what can they not do? They can't divide.
Okay. So we're not going over oppositional growth in detail. I just want y'all to know a few things about it.
Oppositional growth is growth in what? In width. Does it occur in any specific type of bone or all bones? Occurs in all bones.
Does it stop or does it occur throughout life? Okay. Appositional growth is going to occur directly beneath the periosteum.
All bones have a periosteum, which is why all bones can go through appositional growth. Now, why is the periosteum so important? We keep going back to this.
How many layers does it have? And that inner layer, what's its fancy name? Osteogenic, which means it really just makes what type of cells?
Osteoblast, bone cells. Okay. Where are we making new bone in oppositional growth? We're making it in width and where? Beneath what?
Yeah. So basically, we have all these bone cells, right? beneath the periosteum, which means they can make new bone right beneath it.
What type of bone do we look like we're making? Is that spongy bone or compact bone? You remember I kept saying we make spongy bone first, except for one incident. In appositional growth, we create compact bone initially. So every time we make bone in general, it's spongy bone first.
but when we grow in width we make osteons so we're making compact bone now think about your legs your arms any law any bone really long bones are a little easier to think about because they look like trees we know we don't grow in length throughout life and we know we grow in width but do our bones just keep getting bigger and bigger like trees okay what's the word for balance internal balance okay i don't even have this picture I don't. Okay. Homeostasis as much bone that we are producing, what are we also doing to older bone?
Breaking it down so we have a balance. So as we continuously build new bone on the outside, we continuously are breaking down old bone and that way we have a balance so our bones don't become tree trunk flags. Okay, so let's talk about this real quickly. This is the same thing we just did with the comparison of intramembranous and endochondral.
So intramembranous and endochondral, the ones that y'all did on the whiteboards, those are development of bone. Interstitial and appositional is going to be what of the bone? Growth. They both work together as we develop your bone grows, but the processes are a little different.
What type of growth is interstitial growth? What type of growth is appositional? Interstitial growth is the epiphyseal plate.
What type of tissue is your epiphyseal plate? Appositional growth develops directly into what type of bone? Where does interstitial growth occur? Where in long bones?
And what do we call that region in the metathesis? Epiphyseal what? Plate. What's the easier way to say that?
Growth plate. Y'all are gonna be pros at reading my horrible handwriting. Okay, appositional growth occurs where?
Occurs all the time, but where? Beneath the periosteum. No, because location is saying where is it occurring in the bone versus which bone. So if I asked you what bones it occurs in, all bones. If I said where does it occur in the body, specifically it's beneath the periosteum.
Okay? Okay. Interstitial growth, time, basically as soon as you start developing bones, the fetus. But when does it end?
That's fine. I don't really care. Just know that it's late teens, early 20s. Appositional growth is what though? You got it.
I am huge supporter of y'all making charts, tables, comparisons, contrasts. It helps you learn the differences and the similarities. Okay. See y'all Tuesday. Have a great weekend.
It's probably next Thursday, so we're gonna I'm pretty positive we'll finish it Tuesday and even maybe start chapter 9 all that's left is Calcium homeostasis, I forgot that I didn't cover Shit, I didn't do that. I forgot I didn't cover on growth bone. Yes, ma'am. We're at least a day behind So thank you.
Yeah, now we're at least a day behind.