FINAL: Bone Growth, Remodeling, And Repair Flashcards
What is the process of remodeling
Replacement of old bone tissue with new tissue
What structures contain the cells required for remodeling
The periosteum and the endosteum
Which cells does “remodeling” involve
All four cell types: osteogenic, osteocyte, osteoblast and osteoclasts
What are osteogenic cells
Stem cell whose divisions produce osteoblasts
- in endosteum
What are osteoblasts
Immature bone cell that secretes organic components of matrix
- outside of matrix
What are osteocytes
Mature bone cell that maintains the bone matrix
- in the matrix
What are osteoclasts
Multinuleate cell that secretes acids and enzymes to dissolve bone matrix
- located in medullary cavity
What is the general process of remodeling
Activation of osteoclasts, followed by osteoblasts function
Role of osteocytes in remodeling due to force
Osteocytes in lacunae sense the direction of force
Osteocytes secrete chemicals that activate osteoclasts in volksmann’s canal where force is high to initiate remodeling
Role of osteoclasts in remodeling due to force
Break down matrix parallel to lines of force
Role of osteoblasts in remodeling due to force
Fill in tunnels with more matrix -> more matrix
What is the function of human growth hormone (HGH)
General growth of all body tissues, including bone
What is the function of sex hormones (estrogens and testosterones)
Increase bone building activity of osteoblasts
Function of insulin and thyroid hormones (T3, T4)
Promote normal bone growth and maturity
Function of the parathyroid hormone
Increase the number and activity of osteoclasts, promotes recovery of Ca2+ absorption from blood and accelerates Ca2+ deposit by bones
What is the majority of the inorganic matrix is made up of
Calcium hydroxyapatite = Ca5(PO4)3(OH)
What affects the remodeling of the matrix
A combination of forces on the bones, hormones and nutrition
What is osteogenesis imperfecta
Brittle bone disease
What is cartilage
A connective tissue that consists of chondrocytes (cells) that secrete collagen intro a solid, (but not mineralized) matrix
Cells = chondrocytes
Fibers = collagen
Ground substance = solid but NOT mineralized (rubbery)
- also used to repair fractures
Function of cartilage in bone development
Provides the framework for osseous tissue
5 steps of ossification and vasularization
What happens during interstitial growth
An epiphyseal plate contains chondrocytes that help to form new osseous tissue
Growth at epiphyseal plates - leading to increased bone length
What is the resting zone of the growth plate
Toward the epiphysis, site of stem cells
What is the proliferating zone of the growth plate
Massive chondrocyte division and cartilage matrix
What is the hypertrophic zone of the growth plate
Chondrocytes enlarge, create large spaces in the matrix and eventually die
What is the calcification zone of the matrix
Osteoblasts/osteoclasts replace cartilage matrix with osseous matrix
What is appositional growth
Growth at the surface that allows our bones to become thicker (or maintain thickness but increase in diameter)
What is hematoma
Mass of clotted blood that forms around a bone fracture
What is a callus
Fibroblasts and chondrocytes that work to repair a fracture
- callus becomes ossified
