Bone is a rigid organ. It is made up of hard tissue known as osseous tissue. It consists of different types of bone cells such as osteoblasts, osteocytes, and osteoclasts. These cells play a major role in the process of modeling and remodeling.
Bone is continuously remodeled by osteoblasts and osteoclasts throughout the entire life. Osteoblast cells produce bone mass while osteoclast cells absorb bone mass.
Remodeling is a process which is characterized by 4 phases:
- The activation phase is when osteoclasts are recruited.
- The reabsorption phase is when the osteoclasts resorb bone.
- The reversal phase is when the osteoclasts undergo apoptosis and the osteoblasts are recruited.
- The formation phase is when the osteoblasts lay down a new organic bone matrix which subsequently mineralizes.
After achieving peak bone mass, bone remodeling is balanced and the bone mass gets stable for a single or two decades unless and until any loss of bone mass occurs due to age.
This condition occurs when osteoclasts cells absorb more bone mass which leads to an imbalance in bone remodeling and lowers bone density.
This condition occurs when osteoblast cells produce more bone mass which also leads to an imbalance in bone remodeling but increases bone density.