The skeletal system is made of ________

Osteoporosis is a bone disorder which comes as a result of decrease in bone mineral density and mass of bone. Osteoblast activity refers to the bone building during the development of skeletal system. Osteoblasts are responsible for bone forming while osteoclasts reabsorb bones.

If there exists an imbalance between the activity of the osteoblasts and osteoclasts, then osteoporosis may result.

The human skeletal system consists ofbones, cartilage, ligaments and tendonsand accounts for about 20 percent of the body weight. The living bones in our bodies use oxygen and give off waste products in metabolism.

Note:

(a) Muscles and tendons are part of the muscular system.

(c) The vitreous humor is a component of the eye.

(d) Minerals and fat are nutrients, not structures in the body.

Osteogenic cells are undifferentiated with high mitotic activity; they are the only bone cells that divide. Immature osteogenic cells are found in the deep layers of the periosteum and the marrow. When they differentiate, they develop into osteoblasts.

The dynamic nature of bone means that new tissue is constantly formed, while old, injured, or unnecessary bone is dissolved for repair or for calcium release. The cell responsible for bone resorption, or breakdown, is the osteoclast, which is found on bone surfaces, is multinucleated.

Osteoclasts continually break down old bone while osteoblasts continually form new bone. The ongoing balance between osteoblasts and osteoclasts is responsible for the constant, but subtle, reshaping of bone.