Skeletal System Flashcards
Function of skeletal system
Support Movement/leverage Protection Storage of minerals and lipids Blood cell production
Types of bone shape
Long Short Flat Irregular Sesame is Sutural
Structure of long bone:
Diaphysis: shaft; central space called medullary (marrow) cavity, wall of compact bone
Epiphysis: ends; mostly spongy, covered with compact bone
Metaphysis: where diaphysis and epiphysis meet; where bone growth occurs
Structure of flat bone:
Spongy bone between layers of compact bone.
Layer of spongy bone is diploë
Bone tissue composed of:
Matrix and specialized cells
Organic matrix: collagen fibers and proteoglycans 1/3
Inorganic: calcium phosphates 2/3 form hydroxyapatite crystals
Osteogenic cells:
Stem cells located in the periosteum and endosteum.
Produce osteoblasts
Osteoblasts:
Synthesize new matrix
Produce osteiods- cells tightly packed with no calcium.
Osteocytes:
Mature bone cells that no longer divide. Separate from each other
Located in lacunae.
Connected by canaliculi
Maintian protein and mineral content of matrix
Osteoclasts:
Absorb and remove bone matrix
Multi nuclear
Secrets acids and proteins digestive enzymes
Osteolysis
Osteon
Function unit of compact bone.
Central canal
Contains blood, lymph and nerve vessels
Lamellae
Layers of bone matrix
Concentric lamellae
Surround central canal
Interstitial lamellae:
Fills space between osteons
Circumferential lamellae
Outer and inner bone surfaces
Spongy bone
Trabeculae: no blood vessels
Red bone marrow fills space between trabeculae; forms blood cells
Yellow bone marrow: stores bone fat.
Periosteum:
Covers all bones
Outer fibrous layer and inner cellular layer
Contains perforating fibers to connect with collagen fibers in the bone
Isolated bone from surrounding tissue
Provided a route for circulatory and nervous supply
Participated in bone growth and repair
Endosteum:
Incomplete cellular layer that liner the marrow cavity, central canals, and trabeculae
Contains osteoblasts, osteogenic cells and osteoclasts
Active in bone growth and repair
Ossification:
Bone formation without calcium
Calcification:
Deposition of calcium salts
Intrmembranous ossification:
Dermal ossification
Compact and spongy bone develop from mesenchymal CT
Starts around the 5th week of development
Cranial bones and the clavicles
Intramembranous ossification steps
1) M cells differentiate into osteoblasts and produce osteoids
2) osteoblasts are trapped inside pockets that differentiate into osteocytes. Form spicules
3) spicules interconnect and trap blood vessels in bone tissue
4) osteoblasts continue to produce the bone tissue which forms spongy bone
5) remodeling around blood vessels to produce osteons of compact bone.
Endochondral ossification:
Formed from hyaline cartilage
Long, short, flat, and irregular bones
Endochondral ossification steps:
1) chondrocytes in center divide and increase in size matrix calcifies and chondrocytes start to die
2) periosteum developed via conversion to osteoblasts
3) blood vessels invade into diaphysis and form primary ossifiucenter
4) marrow cavity is formed
5) invasion of blood into epiphysis produced secondary ossification center
6) epiphysis are filled with spongy bone and epiphyseal cartilage separates D and E
7) epiphyseal closure happens at 25 to produce an epiphyseal line
