immovable joint between flat bones of the skull united by a thin layer of dense connective tissue

Three types of bone cells take part in this process: osteoblasts, osteocytes, and osteoclasts ( osteon is the Greek word meaning 'bone'). Structure of bonesīone is living tissue that is constantly being renewed throughout life.

By the time an individual reaches adulthood, the number of bones in the body totals about 206.

As an individual ages, certain bones (such as those in the skull and lower spine) fuse or join together, thereby reducing the number. Endoskeletons allow for freer movement and grow along with an organism.Īll humans are born with over 300 bones. Exoskeletons restrict the movement of an organism and must be shed periodically in order for that organism to grow. In animals that have an external skeleton, such as the crab, the skeleton is called an exoskeleton ( exo means 'outside').

DESIGN: PARTS OF THE SKELETAL SYSTEMīecause the bones making up the human skeleton are inside the body, the skeleton is called an endoskeleton ( endo means 'within'). All bones act as storage sites for minerals such as calcium and phosphorus, and certain bones also produce blood cells. The system protects body organs, supports the body, and provides attachment points for muscles to enable body movement.

Strong yet light, the skeletal system is made of living material, with networks of blood vessels running throughout. The word skeleton comes from the Greek word skeletos, meaning 'dried up.' The parts of the skeletal system -the bones and other structures that make up the joints of the skeleton -are anything but dried up.

Immovable joint between flat bones of the skull united by a thin layer of dense connective tissue