Bones ch 6
bone remodeling
ongoing replacement of old bone tissue by new bone tissue
lipid storage
yellow marrow
spongy bone
(cancellous bone) -located where bones are not heavily stressed -trabeculae -no central canal -site of red marrow
compact bone
- dense, hard -diaphyses of long bone -outside edges of epiphyses and irregular bone -made up of osteons
composition of osseous tissue
- ~50% collagen fibers and ground substance - ~50% calcium and phosphorus
Osteons
-Cylindrical structures -vascular -compose compact bone
intramembranous ossification
-mesenchyme (stem) cells transform to osteoblasts in connective tissue -most flat bones in skull
endochondral ossification
-replaces hyaline cartilage with bone -growth in puberty - forms most bones Long bone Development
Functions of the skeletal system
-support -protection -hematapoiesis -mineral homeostasis -lipid storage -movement
endochondral ossification process
1. fetal hyaline cartilage model of bone develops 2. cartilage calcifies and a periosteal bone collar forms around diaphysis -chondrocytes enlarge within shaft and resorb part of cartilage -cartilage undergoes calcification -chondrocytes die, leaving hardened matrix -at the same time, perichondrium is invaded by blood vessels -cells in perichondrium turn into osteoblasts -periochondrium transformed into periosteum -periosteal bone collar formed 3. primary ossification center forms in diaphysis 4. secondary ossification centers form in epiphyses 5. bone replaces cartilage, except the articular cartilage and epiphyseal plate 6. epiphyseal plates ossify and form epiphyseal lines
Movement description
attachment site for muscles
mineral homeostasis description
calcium and phosphorus
trabecular bone (spongy bone) V.S. compact bone
compact bone is hard and less porous -located under periosteum and in diaphyses of long bone trabecular bone is soft and porous -located at the ends of long bone
central canal
contains blood vessels and nerves -found in osteons
Epiphyses
ends of long bone
support description
lower body supports upper body
trabeculae
network of thin tubular bone structures
protection description
protects organs
Hematapoiesis description
red bone marrow
Lamellae
rings around the central canal -sites of lacunae
bone deposition
the addition of minerals and collagen fibers to bone by osteoblasts
diaphyses
the main midsection, or shaft, portions of long bones; each contains a medullary cavity
bone resorption
the removal of minerals and collagen fibers from bone by osteoclasts