So here we have an example problem that says, osteoporosis is a condition where the bone mass decreases making bones brittle and susceptible to fracture. Based on the structure of bone tissue, is osteoporosis caused by an issue with the osteoblasts or the osteocytes and why? Recall from our previous lesson videos that all connective tissues, including bone or osseous tissue, is going to be similar and that the cells take up much less space than the extracellular matrix. If the bone mass is decreasing, what we're saying is that there's going to be less extracellular matrix.
Recall that osteoblasts are blast cells, and blast cells are more active cells that actively secrete and build components of the extracellular matrix. Whereas, osteocytes are site cells, and they are more focused on maintaining the matrix through minor repairs and routine maintenance. Hence, the osteocytes are not going to be actively building the extracellular matrix while the osteoblasts are. With less bone mass, because that means less extracellular matrix, we can assume that this issue involves the osteoblasts.
For that reason, we can put an arrow here and indicate that osteoblasts will be our answer. Now, in reality, osteoporosis is not caused just by one type of cell. It's actually caused by an imbalance in multiple cells functioning improperly. Recall that, in addition to osteoblasts and osteocytes, we briefly mentioned that there are also osteoclasts. Osteoclasts, which we'll talk more about later in our course, are more about breaking down the bone.
Whereas, osteoblasts are more about building up the bone. It's important to have a healthy functioning balance between osteoblasts and osteoclasts in order for bones to function properly. However, osteoporosis results when there is an improper balance between osteoblasts and osteoclasts causing the extracellular matrix to become less, leading to less bone mass and making those bones more susceptible to fracture. But, the correct answer to this example problem is osteoblasts, not the osteocytes. This concludes this example and I'll see you all in our next video.