Skeletal System

Shapes of Bones Long Bones: Longer than they are wide Have a shaft with a head at both ends Made of mostly compact bone. Found in the limbs of the body.

Shapes of Bones Short Bones: Generally cubed-shaped Contain mostly spongy bone Found in the wrists and ankles

Shapes of Bones Flat Bones: Thin, flattened, and usually curved. Two thin layers of compact bone covering spongy bones. Found in the skull, ribs, and sternum

Shapes of Bones Irregular Bones: Bones that do not fit into the previous categories Vertebrae and hip bones.

Structure of a Long Bone Epiphyses: Ends of the long bone. Made of compact and spongy bone. Articular Cartilage: Slippery cartilage that covers the epiphyses. Provides a smooth surface at the joint for movement.

Bone Marrow In adults, the shaft of long bones store adipose called yellow marrow. The only place to find red marrow is in the cavities of spongy flat bones and the epiphyses of some long bones.** -The bones of most young children are made of hyaline cartilage. As you grow into an adult, the cartilage hardens into bone by a process called ossification.

Making & Destroying Bone osteoblasts: bone-forming cells (make bone) Bone Building osteoclasts: bone-destroying cells. Activated when calcium levels fall below homeostatic levels