Bone Modeling and Remodeling
When bone is deformed by way of loading, the osteocytes detect the change and send signals to the osteoblasts and osteoclasts to repair and strengthen the bone.
Osteoblasts, Osteoclasts and Osteocytes Three types of cells make modeling and remodeling possible: osteoblasts, osteoclasts and osteocytes. Osteoblasts are cells that produce bone and are responsible for its mineralization. Osteoclasts do the opposite; they produce a mineral that breaks down the bone tissue. Toomany osteoclasts cause toomuch bone to be lost and shrink the bone mass, but if osteoclasts are too few bones can not get hollowed out enough for the new bone and for the bone marrow. Both imbalances can cause osteoporosis. Osteocytes, is star shaped bone cell, it is the most commonly found cell in mature bone tissue and can live as long as you do. The adult human body has about 42 billion of them and they make up about 90% of bone. Osteocytes do not divide and have an average half-life of 25 years. Osteocytes originate from osteoblasts and are deeply embedded in cortical and trabecular bone tissue. They have an extensive branching processes throughwhich they communicate with osteoblasts and other osteocytes. These signaling pathways play a crucial role in the skeleton’s ability to continually adapt in response tomechanical loading, because osteocytes can sense total mechanical load and trigger biomechanical responses. These responses can either encourage formation of new bone to handle heavier loads or remove bone in the absence of load.
Bone Mineral Density Mechanical loading of a bone is the most important factor of bone strength and influencing muscle size and force, which in turn correlate with bone mineral density (BMD). We call this concept the “bone- muscle unit” because the development of one directly influences the other. This unit has extra importance during childhood and adolescence because accruing lean tissue mass during the formative years affects adult bone strength. The good news is that even as an older adult, loading the bone signals the osteocytes to send messages to the osteoblasts to build more bone and improve bone density. Correct exercise is the key to improving your bone density. If you have any questions about what kind of exercise would be safe for you to do, don’t hesitate to ask your physical therapist.
Bones are living, dynamic organs that serve many functions. Functions include support, protection, aid in movement, along with storing minerals such as calcium and phosphate for other uses in the body. The human skeleton ismade up of two types of bone, cortical and trabecular. Cortical bone, the dense outer layer makes up 80% of the adult human skeleton. Trabecular bone makes up the inner layers that are spongy and honeycomb like. The trabecular bone is found in the scull, pelvis, sacrum and vertebrae. This is where most of our bone minerals are stored. Bone mass reaches its peak density in late teen years. Bones continue to grow and change throughout lifetime and complete bone mass is replaced every 10 years. This process of change is called modeling and remodeling. Bone Modeling refers to the sculpting of the bones inner and outer shape, bone is formed, and old bone is removed. This process happens during childhood and adolescent years. The process allows the bone to grow and changes shape to adapt to the body of an adult. Bone Remodeling happens in adulthood. Remodeling does not change the shape or size like it does in adolescent years, it gradually replaces the bone.
www.pt-specialties.co
Made with FlippingBook - Online catalogs