5 functions of bone
3 types of cartilage and their locations
4 classifications of bone and examples of each
Compact Bone
Smooth looking outer layer, has osteons, lamellar, canaliculi, and central canal
Spongy bone
Internal to compact bone also called trabecular bone, honey comb like, little flat prices of bone called trabeculae (little beams) in living bones the open spaces are filled with yellow or red marrow
Structure of a long bone list all parts
Microscopic structure of compact bone
Chemical composition of bone
Organic: bone cells and osteoid
- ostegenic cells, osteocytes, osteoblasts, osteoclasts. Osteoid=Glycoproteins,proteoglycans and collagen fibers
Inorganic: mineral salts
Calcium phosphate crystals
Endochondral ossification
A bone developes by replacing hyaline cartilage. The resulting bone is called a cartilage or endochondral bone
Except for clavicle all bones inferior to base of skull are formed by endochondral ossification
Intramembranous ossification
A bone develops from a fibrous membrane and the bone is called a membrane bone.
Forms the cranial bones and (frontal, parietal, occipital, and temporal bones) as well as clavicles. Most bones formed by this process are flat bones
How does endochondral ossification happen
How does intramembranous ossification happen?
Osteoblasts
Build bone
Osteocytes
Bone cells located in lacuna of compact bone. Maintains bone tissue
Osteoclasts
Break down bone. Look like snails
Bone growth
During infancy and youth bones lengthen by interstitial growth by growth of the cartilage of the epiphyseal plate until bone growth ends during or after puberty and the epiphyseal plate becomes the epiphyseal line
When and how does bone growth stops
At the end of adolescence chondrocytes in epiphyseal plate divided less often. The plates become thinner and thinner until they are entirely replaced by bone tissue. Longitunal bone growth ends when epiphysis and diaphysis fuse (called epiphyseal closure) only articular cartilage
When does epiphyseal closure happen
18 yrs in females, 21 in males
Bone remodeling
Also called Appositional growth. Is regulated by hormones and stress on the bone. Osteocytes detect stress osteoblasts secrete osteoid on one side of the bone which becomes calcified while on the other side osteoclasts reabsorb bone. Remodeling goes on through out life
Types of fractures
Comminuted fracture
Compression fracture
- Common in porous bones subjected to extreme trauma, such as a fall
Spiral Fracture
Epiphyseal fracture
- occurs where cartilage cells are dying and matrix is calcifying