Week 11: Bone Tissue, Growth and Healing Flashcards
What are the components of bone tissue?
supporting connective tissue, specialized cells, inorganic components (calcium salt deposits) and organic components (collagen fibres)
What is the bone matrix made up of?
70% hydroxyapatite (inorganic) and 30% collagen fibres (organic)
What are the 4 types of bone cells?
osteoprogenitor cells, osteoblasts, osteocytes, osteoclasts
What are osteoprogenitor cells?
stem cells that divide to produce osteoblasts
Where are osteoprogenitor cells located?
in the endosteum and the inner cellular layer of periosteum
What is the main function of osteoprogenitor cells?
assist in fracture repair
What are osteoblasts?
immature bone cells that secrete matrix compounds
What are osteocytes?
mature bone cells that maintain the bone matrix
Where are osteocytes located?
in lacunae and between layers of matrix
What are the functions of osteocytes?
maintain protein and mineral content of matrix, to help repair damaged bone
What are osteoclasts?
derived from stem cells in bone marrow that produce macrophages
What is the function of osteoclasts?
dissolve bone matrix and release stored minerals
What has to be balanced to achieve bone homeostasis?
bone building by osteoblasts and bone breakdown by osteoclasts
What are the features of a compact bone?
osteon (basic transport unit), osteocytes arranged in concentric lamellae around a central canal, perforating canals (perpendicular to central canal), circumferential lamellae (bind osteons together)
What are the features of a spongy (cancellous) bone?
no osteons, open network of trabeculae (spaces between are filled with red and yellow bone marrow)
Where can periosteum be found?
covering compact bone (excluding parts in joint capsules)
What is the function of periosteum?
isolate bone from surrounding tissue, provide a route for blood and nerve supply, participate in bone growth and repair
What are the two layers of the periosteum?
fibrous layer and cellular layer
Where can endosteum be found?
on the inside of compact bone
Define osteogenesis
bone formation
what is ossification?
the process of replacing other tissues with bone
What are the forms of ossification?
endochondral ossification and intramembranous ossification
What is endochondral ossification?
ossifies bones that originate as hyaline cartilage
What is intramembranous ossification?
produces flat bones
How is blood supplied to mature bones?
nutrient artery and vein, metaphyseal vessels (supplies epiphyseal cartilage), periosteal vessels (supplies superficial lamellae)
How is a fracture repaired?
1- bleeding, producing a clot
2- cells of endosteum and periosteum move into fracture zone
3- osteoblasts form spongy bone
4- osteoblasts, osteocytes and osteoclasts remodel he fracture or up to a year
