Answer to Question 1
Bone remodeling is a dynamic process involving the osteoblasts (building of new bone) and the osteoclasts (breakdown of old bone). The cycle of bone breakdown and rebuilding is called bone remodeling or bone turnover and is a necessary process to keep bones strong.
Answer to Question 2
Bones are covered by a thin membrane called the periosteum, which is made up of connective tissue and hundreds of small blood vessels and nerves. Underneath the periosteum is a layer of hard, dense bone called cortical bone or compact bone. Cortical bone provides strength. Cortical bone surrounds another layer called trabecular bone. Trabecular bone is not as dense as cortical bone. Trabecular bone is a web-like structure. The trabecular bone contains the bone marrow that produces the red blood cells, white blood cells, and platelets. The ratio of trabecular bone to cortical bone differs depending on the type of bone in the body. In the very core of each bone are large blood vessels, lymphatic vessels, and nerves that allow transport to and from bone tissue of hormones, nutrients, and neural impulses.