Our bones are constantly being recycled to keep them healthy. One type of cell in the bone breaks it down and another reforms it – a balance controlled by the brain, via networks of nerves running through our body. The sympathetic nervous system
– the network responsible for immediate actions such as sweating and quickening the heart – restricts bone tissue formation, whereas the parasympathetic system
– responsible for long-term actions such as digestion – is thought to stimulate it. Parasympathetic nerves, and receptors (seen here dyed red in a bone cell, called an osteoclast
, from a mouse) have only recently been found in bone tissue. Understanding the balance is important for research into diseases such as osteoporosis
, which is caused by excessive bone tissue loss, usually in later life, creating a high risk of fractures.
Written by Mick Warwicker