Chapter 6 Flashcards
What are 6 main roles of bone
Support, movement, protection for organs, mineral homeostasis, hemopoiesis, triglyceride storage
Define disphysis
Bone shaft
Define epiohyses
Growth plates at ends of bone
Metaphases
Region between diaphysis ans epiphyses, contains epiphyseal plate
What is articular cartilage
Hyaline cartilage covering epiphyses at joints, reduces shock and friction. Avascular, no perichondrium
What is periosteum?
Connective tissue sheath covering bone. Contains blood vessels. Has outer fibrous layer and inner osteogenic layer. Protects bone, assists in repair, provides attachment for ligaments
What are perforating fibres?
Attaches periosteum to bone
What are osteoprogenitor cells?
Originate from mesenchyme, unspecialized bone stem cells, only ones that divide. Found in periosteum, endosteum, and central canals
How do blood vessels penetrate bone?
Through transverse interosteonic canals
How do osteocytes communicate?
Gap junctions
Where is spongy bone tissue found?
In epiphyses, rim of medullary cavity, short, flat, sesamoid and irregular bones
Where is red bone marrow found?
Hip bones, ribs, sternum, vertebrae, proximal ends of humerus and femur
What are the blood supplies for bone
Outer part of bone and periosteum–periosteal arteries
Inner part of bone, spongy bone, and marrow–nutrient artery
End of long bones–epiphyseal and metaphyseal arteries
What are the two types of osteogenesis?
Intramembranous and endochondral
What are the steps for intramembranous ossification?
- Development of ossification centre
- Calcification
- Formation of trabeculae
- Development of periosteum
What are the steps of endochondral ossification
- Development of cartilage model
- Growth of cartilage model
- Development of primary ossification center (proceeds inward)
- Development of medullary cavity
- Development of secondary ossification center
- Formation of articular cartilage and epiphyseal plate
What bones are grown from each method of ossification?
Endochondral–most bones, long bones
Intramembranous–flat bones of skull, most facial bones, mandible and clavicle
What cells form medullary cavity?
Osteoclasts
What is interstitial and appositional growth?
Interstitial–length
Appositional–width
Primary vs secondary ossification center
Primary in diaphysis, secondary in epiphysis
How does growth occur at epiphyseal plates?
Growth occurs from zone of proliferating cartilage, secretes ECM. The proliferating cartilage creates more chondrocytes which develop in the zone of hypertrophic cartilage. The ECM calcifies, and chondrocytes die, and endochondral ossification occurs.
How is the epiphyseal plate anchored to bone?
At the zone of resting cartilage, through chondrocytes
How does appositional growth occur?
- Periosteal cells differentiate into osteoblasts, secrete ECM, forms ridges
- Ridges fold and fuse to form tunnels, enclosing blood vessels
- Endosteum osteoblasts form concentric lamellae to form osteon
- As osteon forms, osteoblasts deposit new circumferential lamellae
What are the parts to the feedback cycle for calcium?
Receptors: parathyroid gland cells
Input: cAMP
Control center: PTH gene
Output: PTH
Effectors: osteoclasts and kidneys
