Gross Anatomy of Bone: Bone Marrow - Video Tutorials & Practice Problems
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Bone Marrow
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Video transcript
We've previously said that the inside of bone is filled with all sorts of different little spaces, but, of course, those spaces aren't just empty. They're filled with something, and what they're filled with is bone marrow. We're gonna talk about bone marrow in a lot more detail here. So we'll just start out by saying that there are gonna be 2 types of tissues that fill the space inside of bone, and those types of tissue are gonna be the red marrow and the yellow marrow. Now we'll start with red marrow. Red marrow is just gonna be the site of hematopoiesis, and hematopoiesis is just a long, kind of difficult to pronounce word that means the formation of blood cells. And you're probably familiar with that as a as a function of bone marrow. Most people, if you ask them what does bone marrow do, they know that it produces blood. If you're thinking about that as a function of marrow, you are thinking about red marrow. Now red marrow is gonna be found only in spongy bone in adults. Now importantly, not all spongy bone is filled with red marrow, but if you're looking for red marrow, you gotta look in the spongy bone. And red marrow is gonna be the primary marrow type in babies. When a baby is born, they really only have, that red marrow to produce a lot of blood because they're growing. And as you age and get older, you don't need to be making as much blood all the time, so more and more of your marrow becomes yellow marrow. We'll talk about that in just a second. 1st, I wanna look down at this picture, though. So we have the end of the femur here, and we're looking at it in cross section. And if we look up at the end of the femur, where, it's all red, that's the spongy bone, and it's filled with that red marrow. And it's showing us what it's doing here. It has a factory. This little cartoon of the factory used to think, well, what is that red marrow making? Well, what's coming out of the factory? We have platelets, red blood cells, and white blood cells. All our blood cells are being made in that spongy bone in the red marrow. So yellow marrow. Yellow marrow is gonna be the site of triglyceride or just fat storage, and it's yellow because fat is kinda yellowish in color. This is gonna be found in spongy bone, but it's also gonna be found in that medullary cavity of a long bone. Now we haven't defined the medullary cavity yet, but the shaft of a long bone, you may know, is gonna be hollow and filled with bone marrow. That hollow space is is the medullary cavity, and we're gonna talk about that in more detail in a coming video. So when you think of bone marrow, a lot of people know that if you crack open a long bone, you can see that marrow. When you crack open a long a bone like that or if you feed a marrow bone to your dog, for example, you are seeing the yellow marrow, and sometimes people like to eat it because that tastes good. So yellow marrow, though, we should know that it can also revert to red marrow. As you age, red marrow becomes yellow marrow, but if you need a lot of blood for some reason, some yellow marrow can go back and become red marrow and produce more blood for your body. So how much red and yellow marrow you have isn't a fixed thing. Yellow marrow is going to be the primary marrow type in adults. So if you are an adult, most of your marrow is yellow marrow. Now to illustrate this, again, we see the femur, and down here in the shaft of the bone, it's colored yellow for that yellow marrow, and we see a refrigerator. And that refrigerator is supposed to illustrate that it's holding all sorts of nutrients, and we can see all sorts of good foods in here. Well, it's mostly meat and cheese, and I'm vegan, so I wouldn't eat that. But you get the idea. There's some fat cells on the bottom. It's storing nutrients for your body. Okay. So remember, red marrow, hematopoiesis, produces blood found in spongy bone. Yellow marrow stores nutrients in the form of fat found in spongy bone and the medullary cavity. And with that, I'll see you in the next video.
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example
Gross Anatomy of Bone: Bone Marrow Example 1
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This example tells us that Priyanka is told that she has the bone disorder myelodysplastic syndrome, and she needs a blood transfusion. Based on this information, what type of bone marrow do you think is affected in myelodysplastic syndrome? And explain your reasoning. Alright. Based on this information, there's not a lot of information there. There's myelodysplastic syndrome, and she needs a blood transfusion. Myelodysplastic, that's a big, long word. I'm not gonna even worry what it means or or how to break it down because we have this information about a blood transfusion, and that's gonna tell me something about what type of bone marrow is affected. To remind ourselves of this, we have a femur over here on the right, and this picture shows a femur at the epiphysis. We see it's red to show red marrow, and out of that, we have this arrow showing that all these different types of blood cells are made, red blood cells, white blood cells, and plates. In contrast, in the diaphysis, it's yellow, showing that that's yellow marrow, and there we have adipose tissue or storage of fat triglycerides. So just knowing that, knowing someone that needs a blood transfusion, it must have to do with the red marrow. So I'm gonna write down red marrow, and my reasoning is the condition concerns blood. Now obviously, not all blood conditions have to do with red marrow, but if it has to do with the type of marrow, it's gonna have to do with the red marrow. Okay. Myelodysplastic syndrome is actually a group of conditions that all affect blood cells developing properly. With that, we have more practice problems to follow, and I'll see you there.
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Problem
Problem
Which of the following could be a reason why babies have relatively more red marrow than adults?
A
Babies require red blood cells to be produced quickly to accommodate growth.
B
The red marrow will aid in heat production keeping babies warm.
C
Red marrow is located in spongy bone and babies' bones need to be softer than adults'.
D
The triglycerides in red marrow aid in brain development.
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Problem
Problem
In 1820, George Pollard and Charles Ramsdell were rescued after 93 days at sea in a small whaling boat after a sperm whale charged and sank their ship in what would become the inspiration for the novel Moby Dick. The two men were found adrift, sucking on the broken long bones of their dead shipmates. What nutrients were they receiving by sucking on the bones?
A
Glucose and glycogen from the marrow.
B
Triglycerides from adipose tissue.
C
Protein and amino acids from epithelial tissue.
D
NaCl from the bone matrix.
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