An
osteoclast (from the Greek words for "bone" (ὀστέον), and "broken" (κλαστός)) is a type of
bone cell that breaks down
bone tissue. This function is critical in the maintenance, repair, and
remodelling of
bones of the
vertebral skeleton. The osteoclast disassembles and digests the composite of hydrated protein and mineral at a molecular level by secreting acid and a collagenase, a process known as
bone resorption. This process also helps regulate the level of blood calcium.