Bone homeostasis involves multiple but coordinated cellular and molecular events. Two main types of cells are responsible for bone metabolism: osteoblasts (which secrete new bone), and osteoclasts (which break bone down). The structure of bones as well as adequate supply of calcium requires close cooperation between these two cell types and other cell populations present at the<unk>  sites (eg. immune cells). Bone metabolism relies on complex signaling pathways and control mechanisms to achieve proper rates of growth and differentiation. These controls include the action of several hormones, including parathyroid hormone (PTH), vitamin D, growth hormone, steroids, and calcitonin, as well as several bone marrow-derived membrane and soluble cytokines and growth factors (ex. M-CSF, RANKL, VEGF, IL-6 family...). It is in this way that the body is able to maintain proper levels of calcium required for physiological processes. Thus<unk>  is not just occasional "repair of bone damage" but rather an active, continual process that is always happening in a healthy body. Subsequent to appropriate signaling, osteoclasts move to resorb the surface of the bone, followed by deposition of bone by osteoblasts. Together, the cells that are responsible for<unk>  are known as the basic multicellular unit (BMU), and the temporal duration (i.e. lifespan) of the BMU is referred to as the<unk>  period.
Bone remodeling
Bone resorption
Bone healing
Endochondral ossification
Osteostimulation
Vasculogenesis
Lymphangiogenesis
Neuromodulation 