After adolescence, bones stop growing longer. They do however continue to grow. How do bones remodel and undergo repair
http://www.ncbi.nlm.nih.gov/pubmed/17308163
Bones are dynamic and constantly undergo a remodeling process throughout our lives. This process involves two main activities: bone resorption and new bone formation. Bone resorption refers to the removal of old or damaged bone tissue, while new bone formation involves the deposition of fresh bone tissue. Together, these processes allow bones to remodel and repair themselves.
Bone resorption is carried out by specialized cells called osteoclasts. These cells break down and remove old or damaged bone tissue by secreting enzymes that dissolve the bone matrix. Osteoclasts are influenced by various factors, including hormones, mechanical stress, and inflammation. Once the old bone is broken down and removed, the second phase of bone remodeling begins.
New bone formation occurs through a process called ossification or osteogenesis. Osteoblasts, another type of specialized bone cells, are responsible for the production and deposition of new bone tissue. These cells synthesize proteins and collagen, which form the organic matrix of bone. They also play a crucial role in mineralizing the bone matrix by depositing calcium and other minerals.
The remodeling and repair of bones occur in response to several factors. Mechanical stress or loading, such as weight-bearing exercise, stimulates bone remodeling by activating osteoblasts to add new bone in areas subjected to greater stress. Additionally, hormonal factors, such as the influence of growth hormone, sex hormones (estrogen and testosterone), and parathyroid hormone directly affect bone remodeling.
Moreover, bone remodeling is a continuous process that helps maintain bone strength and integrity. It allows bones to adapt to the changing demands of the body, repair tiny micro-damages that occur daily, and replace old bone tissue with new material. This process is critical for bone health and helps prevent conditions like osteoporosis, which is characterized by reduced bone density and increased fracture risk.
In summary, bones remodel and undergo repair through a dynamic process involving bone resorption by osteoclasts and new bone formation by osteoblasts. This process is influenced by a variety of factors, including mechanical stress, hormonal regulation, and ongoing maintenance requirements of the skeletal system.