Microscopic Anatomy of Bone Flashcards
What are the four different types of Bone Cells?
- Osteoprogenitor Cells
- Osteoblasts
- Osteocytes
- Osteoclasts
Osteoprogenitor Cells
Will differentiate and become bone cells, when it matures it becomes osteoblasts
Osteoblasts
Secrete osteoid, forming bone matrix
Osteocytes
Mature bone cells that sense stress/strain on the bone
Osteoclasts
Break down bone, activate when there’s low calcium
Compact Bone
Strong, Heavy
Spongy Bone
Porous, not as strong as compact, has trabeculae (pieces/bridges of bone that make up spongy bone)
Osteon
- The basic unit of compact bone
- AKA Haversian system
- Cylindrical structures
- Run parallel to the diaphysis
Central Canal
Spaces at the core of each osteon
Concentric Lamellae
Make up osteon
What are the three structures in Compact Bone?
- Osteocytes (embedded in)
- Canaliculi
- Perforating canals
Canaliculi
Little canal where osteocytes can communicate with each other
Perforating Canals
Run perpendicular to central canals
Spongy Bone Characteristics
- Lack osteons
- Trabeculae contains parallel lamellae
- Distributes stress from mechanical forces across framework
Ossification
The formation of bone connective tissue
Intramembranous Ossification
(No cartilage stage)
How flat bones are formed (Ex. Skull)
Endochondral Ossification
How long bones are formed
Intramembranous Ossification Process
- Produces flat bones of the skull, some facial bones, mandible, and central portion of clavicle
- Bones develop from mesenchyme membrane
- Calcification entraps osteoblasts within lacunae in bone matrix
- Osteoblasts become osteocytes
- Woven bone and surrounding periosteum form
- Lamellar bone replaces woven bone, as compact and spongy bone form
Endochondral Ossification Process
- Formation of most bones of skeleton: upper/lower limbs, pelvis, vertebrae, ends of clavicles
- Bones develop from hyaline cartilage model
How do bones develop from the hyaline cartilage model?
- The fetal hyaline cartilage model develops
- Cartilage calcifies, and a periosteal bone collar forms
- The primary ossification center forms in the diaphysis
- Secondary ossification centers form in the epiphyses
- Bone replaces cartilage, except the articular cartilage and epiphyseal plates
- Epiphyseal plates ossify and form epiphyseal lines
A long bone’s growth in length
Growth within
Growth in a bone’s diameter
Growth on outside, covers inside
Epiphyseal Plate
- Site of interstitial growth
- Consists of five distinct microscopic zones
Effects of exercise
When physically active it causes the bone to be more mineralized because the bone senses strain/stress
