#BoneCells

#Biology

#AnatomyofBones.

Bone Cells: Definitions & Functions

• Bones have two kinds of cells.

• That may not seem like much, but they coordinate their activities to create a balanced system that modifies and maintains your entire skeleton.

• This process is similar to a construction company that redesigns homes.

• For example, each team member contributes something unique when modifying a home structure: one removes a wall, another creates a deck, and others maintain these modifications, all while they communicate with each other to coordinate their efforts.

• Your bone cells do the same thing.

Osteogenic Bone Cells

• Let's begin by putting together the construction crews for your bones. Some members come from osteogenic cells, which are located in the surface lining of bones and in bone marrow.

• The term 'osteo' means bone and the suffix 'genic' refers to genesis, or the start of something new, such as these crews. Osteogenic cells are undifferentiated, meaning they are undefined, and eventually become other kinds of cells. In other words, they are stem cells.

  
  

• As they prepare to change, stem cells enter a stage of development in which they are one step away from becoming a definitive cell type.

• At this point they are called precursor cells. For example, as in the daily activities of construction sites, two osteogenic cells could initially show up and either one could become a painter or a carpenter.

• However, each task requires more specific training, or development. When training ends there would be two precursor cells: one for painting and the other for carpentry.

  When they are instructed to practice their craft, these precursor cells will finally change, or differentiate, into their defined roles.

• Biologically, the instructions come from hormones that bind to receptor sites on a particular cell and tell it to change into something else. Many kinds of cells in the body can differentiate. They don't have to be osteogenic. In the bones, osteoblasts are a good example.

1. Osteoblast Bone Cells

• Osteoblast cells are the creators of bone material. The suffix 'blast' is from the Greek word 'blastos,' which means to germinate or sprout.

• The function of osteoblasts is to make various proteins used in the matrix of bone. The term matrix is generic for a surrounding substance in which other things are embedded, like cement in which re-bar is inserted.

• Osteoblasts also control the mineralization of the matrix to make it solid and strong. Basically, they are cement mixers and adjust the content and consistency of the matrix (cement) that will be used to shape the foundation of bones.

• After osteoblasts finish their job, some become trapped by the very matrix they produced. These cells differentiate into osteocytes, another kind of bone cell. Other osteoblasts remain at the surface of bones and differentiate into cells that line and protect the outer layers.

• Osteoblasts are created by precursor cells found in bone marrow which can differentiate into either fat cells or osteoblasts, depending on what chemical signal is sent to them from other cells or glands. Therefore, osteoblasts resemble bone marrow cells in some ways, such as having only one nucleus.

• Osteoblasts also communicate with other bone cells by secreting molecules of their own. This helps regulate the entire process of bone modification so that all cells know when to stop or begin their contribution to reshaping bones.

2. Osteoclast Bone Cells

• For bones to reshape themselves over time, their matrix must be broken down as well as built up. To accomplish this, osteoblasts team-up with osteoclasts, which break down bone material.

• The suffix 'clast' refers to destruction, so osteoclasts are the demolition experts.

• Like osteoblasts, they are formed from precursor cells, but a different kind which circulates in the bloodstream. Therefore, osteoclasts have multiple nuclei, a characteristic shared by some blood cells.

Diagram

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