Skeletal System Basics
How many bones are in the adult skeleton?
206 bones
What is the shaft of a long bone called?
Diaphysis
Which bone cells build new bone?
Osteoblasts
What material do bones first form from?
Cartilage (hyaline cartilage model)
What bone protects the brain?
Skull (cranium)
What are the two main divisions of the skeleton?
Axial skeleton and appendicular skeleton
What is found inside the medullary cavity?
Yellow marrow (fat storage)
Which cells break down old bone?
Osteoclasts
Where does primary ossification occur?
Diaphysis (shaft of long bone)
What structure protects the heart and lungs?
Rib cage (ribs and sternum)
Name three functions of the skeletal system.
Support, protection, movement, mineral storage, blood cell formation
What covers the outside of a bone?
Periosteum
Which cells are mature bone cells trapped in the matrix?
Osteocytes
When do secondary ossification centers form?
After birth, at the epiphyses (ends of long bones)
What is the only movable bone in the skull?
Mandible
Which division includes the skull, ribs, and spine?
Axial skeleton
What type of bone tissue is dense and strong?
Compact bone
Which bone cells act as stem cells?
Osteogenic (osteoprogenitor) cells
What remains as cartilage after ossification?
Growth plates (epiphyseal plates) and articular cartilage
What bone is most commonly fractured?
Clavicle (collarbone)
Which skeleton allows limb movement?
Appendicular skeleton
What structure is responsible for blood cell formation?
Red bone marrow
How do osteoblasts and osteoclasts work together?
Osteoblasts build bone while osteoclasts break it down to remodel and maintain strength
What role do osteoclasts play during bone growth?
Osteoclasts remove old or excess bone tissue to shape and remodel bones
Name two flat bones and one long bone.
skull, sternum; Long bone – femur