Biology - Chapter 11.6: Skeletal System Flashcards
Long bones
- Compact and spongy bone
- Includes: epiphysis, diaphysis, medullary cavity, metaphysis, epiphyseal plate
Short bone
- .g. parts of the wrist
- support
Flat bone
- e.g. skull
- protection
Sesamoid bone
- e.g. kneecap
- found within tendons to help muscle pull
Irregular bones
- e.g. pelvis
- look irregular
Bone Remodeling
Constant back and forth between ossification (bone formation) and resorption (bone loss)
Osteoprogenitors
Immature precursor cells that differentiate into osteoblasts
Osteoblasts
- Build bone by secreting proteins and utilizing blood calcium
- Differentiate into osteocytes once trapped
Osteocytes
-Live in lacunae of osteons to maintain bone
Osteoclasts
- Resorb bone, bringing calcium back into the blood
- Derived from monocytes
Parathyroid hormone
- secreted by parathyroid gland
- increases blood calcium levels
- stimulates osteoclasts
- depress osteoblasts
Calcitonin
- secreted by thyroid gland
- decreases blood calcium levels
- depresses osteoclasts
- stimulates osteoblasts
Material of Bones
Organic: osteoid
Inorganic: hydroxapatite
Intramembrous ossification
- Mainly for flat bones
- Bone is created directly within fibrous membrane
- Osteoblasts start by secreting osteoid, which hardens and houses osteocytes
- Cortical bone is then created
Endochondral ossification
- Bone is created indirectly through a cartilage model, mainly for long bones
- Cartilage model calcifies during fetal development, creating ossification centers (primary & secondary) that help form the features of long bone
Fibrous connective tissue
- has a matrix made up of fibers
- Tendons, Ligaments, Periosteum, Endosteum
Cartilage
- avascular
- not innervated
- chondroblasts build cartilage by secreting collagen and elastin
- hyaline, fibrous, elastic
Hyaline cartilage
- slightly flexible
- provide support and stability to joints
Fibrous cartilage
- high rigidity and resists tension
- knee, intervertebral discs
Elastic cartilage
- highly flexible
- ears, epiglottis
Synarthroses
Dense, fibrous joints that do not move
Amphiarthroses
Cartilaginous joints that partially move
