The human skeletal system is composed of 206 bones which shape the body and allow us to move. It serves as protection for our soft organs such as the brain, lungs, and heart and provides muscle attachment for motion.

The bones store many minerals like calcium and phosphorus and produce red blood cells.
Bone is composed of four layers:
Skeletal System Diagram copyright © 1996 by John Green
Bone is living tissue that changes constantly. Old bone tissue dies and is replaced by new bone tissue. The human skeleton grows and strengthens until about the age of 18 in women and 21 in men. Bone mass, which is the amount of bone tissue in the skeleton, continues to grow until about the age of 30.
Osteopenia and osteoporosis - both are conditions that cause low bone density, but with osteoporosis, bones are more fragile with a high risk of fracture.
Arthritis and other chronic joint problems - is a group of diseases that can cause pain, stiffness and swelling in joints.
Nutrition - A diet rich in calcium, magnesium and vitamin D is important for maintaining healthy, strong bones. Follow a healthy diet plan that includes all the food groups. Fruits and vegetables are just as important for building strong bones as dairy products. Avoid processed foods.
Regular Exercise – Exercise helps increase bone density at every age. The best exercise for strengthening bones is weight bearing exercise, also referred to as weight training or strength training. Stretching is very important to help maintain flexibility.