Bones & Cartilage

Skeletal System Introduction Functions Support Mineral/Lipid Storage Blood Cell production Protection Leverage Types Compact – organized into osteons Spongy – forms a lattice of bony struts aka trabeculae

The Skeleton 206 bones Each bone is an organ Axial division Skull Vertebral column Sternum Ribs Hyoid bone Appendicular division Pectoral girdle Upper limbs Pelvic girdle Lower limbs

Classification of Bones

Periosteum: tough, fibrous membrane that encases the bone Outer layer where tendons and ligaments attach Inner cellular layer: osteoblasts (bone growth and repair) and osteocytes (mature bone cells that maintain the matrix) Diaphysis: the shaft of the bone Made mainly of compact bone Interior cavity (medullary cavity) lined with spongy bone and stores marrow Endosteum: membrane that surrounds the medullary cavity Contains osteoclasts  bone remodeling or mineral release Metaphysis: in between diaphysis and either epiphysis The epiphyseal plate in early childhood development Epiphysis: located at both proximal and distal ends of the bone Bone Structure

Histology of the Bone Osteons: aka Haversian systems Concentric lamellae rings Lacunae (contain the osteocytes) Perforating canal (where blood vessels, nerves, and lymph vessels enter the bone via the periosteum)  run perpendicular to central canals Central canal: center of the osteons Canaliculi: facilitate nutrient, gas, and waste exchange with the blood Bone continuously is remodeled throughout life Distal end of a bone is remodeled, the diaphysis may never be

Bone Modeling/Remodeling https://www.youtube.com/watch?v=0dV1Bwe2v6c\

Cartilage No nerves No blood vessels Rubber like padding

Bone comes from cartilage?

Growth Plates

Repairing Broken Bone

What else can the skeleton tell us? https://www.youtube.com/watch?v=PJ7A6Nw0My4&t=3s