So let's begin with the osteoblasts. So the osteoblasts are basically those cells inside the bone that are responsible for building that bone, for building and secreting the extracellular matrix. So that means these osteoblasts are capable of secreting collagen into our extracellular matrix. And these cells are capable of taking up calcium as well as phosphate from the blood and depositing it into the extracellular matrix. So basically, these are the cells that are responsible for building bones. They secrete organic as well as inorganic matter such as collagen, calcium as well as phosphates, and are responsible for creating the extracellular matrix that we just discussed above.