What is an osteoblast? The clue is in the name; osteo – pertaining to bones. In simple terms, osteoblasts are cells which help new bone formation.
Osteoblast cells are formed in bone marrow. Their function is to build new bone. A part of what is termed the bone matrix, osteoblasts also help with mineralising bone. They have counter-cells which are known as osteoclasts and these contribute to the breakdown of bone. Because the bones of the body are under a process of constantly being created and broken down, osteoblasts are a vital part of the cycle.
Weakening of the bones is common in older people and this is due to a decrease in the production of osteoblasts, often leading to Brittle Bone disease (osteogenesis imperfecta). Osteoblasts need calcium to help with the creation of new bone. A lack of calcium in the body is a significant contributory cause to bone weakness in older people, frequently leading to fractures.
There are variations on the osteoblast, one of which is the osteocyte. This cell becomes trapped within the bone matrix which prevents is dividing normally. Via extensions for communication with other cells, osteocytes perform the function of shifting waste and nutrients around the bone matrix. Bone-lining cells, which have changed their function, become flattened and attached to the bone surface.
This version of the cells is thought to trigger the activity in both osteoblasts and and osteoclasts. They respond to hormones in the body and cause the correct type of cells to generate for a given situation. They are also functional to deciding where and how much calcium goes into the bone matrix.
Osteoblasts don't only function as builders of new bone. They also work to repair and shore up existing bone matter. Working in tandem with osteoclasts, the cells cause the constant renewal and well-being of bones within the human body. This is known as bone remodeling. This is usually triggered by a significant injury to a bone such as a break or due to disease.
The process, simply, involves osteoclasts being triggered to clear away damaged bone using specific enzymes, the resultant pitting being known as lacunae. This action is followed by repair and creation of new bone by the osteoblasts. Osteoblasts have a lifespan of roughly three months, whilst osteoclasts live for little more than two weeks. Both are stimulated by growth hormones.