Flashcards in Bone: Structure and Function Deck (92):
The composition of bone is similar to _____
Composition of bone is _______ overlaid on a _________ scaffold
2. Collagen I scaffold
What are the Non-collagenous proteins in bone?
5. Matrix Extracellular Phosphoglycoprotein
By percentage what is the composition of bone?
What makes up the inorganic portion of bone?
What makes up the Organic component of bone?
5% noncollagenous proteins
Name 3 physiological roles of bone
2. Calcium Homeostasis (9-10mg/DL)
3. Reservoir for growth factors in tissue repair
Bone contains both ________ and _______ progenitor cell populations in marrow
What is the basic macrostructure of bone?
Outer layer of dense compact/cortical bone with an inner cavity
What is contained within the inner cavity of bone?
Marrow and cancellous/trabecular bone
What colors is marrow?
Red or yellow
T/F Bone is highly vascular with a network of blood vessels
What are the 3 organizational units in the macrostructure of compact bone?
2. Concentric/osteonic lamellae
3. Interstitial lamellae
What is circumferential compact bone?
Outer ring of bone tissue
What is Concentric/osteonic lamellae?
What is the interstitial lamellae?
They fill the space between concentric lamellae; former concentric lamellae
What is the basic functional unit of compact bone?
Osteons form cylinders that run in what orientation?
parallel to the long axis of a bone
Osteons are formed from ______
What would you call a concentric ring of bone, built around a canal housing a capillary?
What would we call the canal that runs in the osteon?
What connects haversian canals and links osteons?
What do we call the spongy bone that is much less densely arranged than compact bone?
Where would you find cancellous bone?
1. At the ends of long bones, in apposition to joints
2. Associated with the marrow spaces
What purpose does cancellous bone serve?
Provides structural support for marrow tissues, highly vascular
What type of bone is a site of blood cell production and supports mesenchymal and hematopoietic progenitor cell populations?
Define the periosteum
Connective Tissue layer attached to the outer surface of a bone by Sharpey's fibers
What are the two layers of the periosteum?
1. Outer fibrous layer
2. Inner layer in apposition to the bone surface
Which layer of the periosteum is both highl cellular and vascularized?
What is the Endosteum?
Loose Connective tissue covering the inner surface of both cancellous and compact bone
What separates the marrow from the bone and is poorly defined histologically?
What is the origin of Osteoblasts?
What would you call an encapsulated osteoblast?
What is the origin of Osteoclasts?
Carefully regulated interaction between Osteoblasts, Osteocytes, and Osteoclasts is responsible for bone formation, repair, and maintenance T/F
What is the mononucleated cells that synthesize osteoid matrix?
In the head, what is the origin of Osteoblasts?
T/F Osteoblasts have a role in both bone formation and repair
How do osteoblasts communicate with each other?
*They do not form complexes
What bone cells produce and secrete collagen and non collagenous proteins via vesicles?
Osteoblasts secrete growth factors into _______
*Then growth factors are sequestered
What are the growth factors secreted by Osteoblasts?
3. IGF I & II
What happens to Osteoblasts after bone formation?
They flatten and form bone lining cells
What do you call osteoblasts which embed themselves into bone matrix?
Terminal differentiation of osteoblasts forms what?
What forms interconnected lacunae in the bone tissue?
Osteocytes have cellular processes which interact with surrounding bone tissue. What purpose do these processes serve?
2. Coordination of odontoblast/osteoclast activity
T/F Osteocytes possible work in conjunction with bone lining cells
What would you call a large multi-nucleated bone cell that is a fusion of monocytes?
Which bone cell is activated in inflammation (IL-1B, TNF-a)
What makes osteoclasts important in dentistry?
What is the key marker for osteoclasts?
Tartrate Resistant Acid Phosphatase (TRAP)
What mediates the attachment of osteoclasts to bone surface?
2. Cytoplasm adjacent to surface rich in Talin
T/F In opposition to bone, Osteoclasts form a ruffled border
Osteoclasts form resorption pits known as ___________
What do osteoclasts secrete into Howship's lacunae?
1. Hydrogen ions
2. Matrix degrading enzymes
What is the Lamina limitans?
The zone between the howship's lacunae and intact bone
Trancytosis of matrix components would be associated with which bone cell?
What supplies new osteoblasts/osteoclasts in bone cell recruitment?
Progenitor cell populations
What triggers progenitor cells to differentiate?
1. Signaling cascades
2. Tissue damage
4. Repair signals
T/F Bone formation is controlled by the complex interactions between osteoblasts and osteoclasts
Bone formation is a balance between _____ and ____ signals
Osteoblasts regulate osteoclast function T/F
What system is associated with Osteoblasts regulating Ostoclast function?
What does RANKL stand for?
Receptor Activated Nuclear factor kB Ligand
*Associated with Osteoblasts
What does RANK stand for?
Receptor Activated Nuclear Factor kB
*Associated with Osteoclasts
What does OPG stand for and what does it do?
*Produced by osteoblasts and binds RANKL
How do long bones form?
How do bones of the skull form?
T/F Endochondral and intramemranous ossification are exclusive processes
What is sutural bone growth?
Fusion of skull plates
T/F Vascular supply is very important in ossification
What type of formation is bone formed formed on a hyaline cartilage pattern?
Condensation of mesenchymal cells into chondrocytes happens in what type of bone formation?
In endochondral ossification ____ is secreted, minerlizes and is broken down by _______, which allows what?
3. Penetration of vasculature
What does the vasculature bring with it ?
Mesenchymal cells which differentiate into osteoblasts
What makes up primary spongiosa?
Bone matrix surrounds remaining mineralized collagen forming mixed spicules
In endochondrdal ossification, what gradually removes mineralized cartilage and develop marrow cavity?
In endochondral ossification ______ form in the epiphyses of some long bones
Secondary growth centers
In intramembranous formation, ______ condense in fibrous connective tissue, differentiating into ________ and forming an ossification center
1. Mesenchymal cells
In intramembranous formation, After mesenchymal cells condense what happens?
Osteoid is secreted into the connective tissue matrix and is penetrated by blood vessels
*Leads to rapid formation of mineralized 'woven bone'
In Intramembranous formation, what happens to the woven bone?
Woven bone remodeled into mature trabecular bone with a collar of cortical bone around it
Sutures are ______ connective tissue bands between plates
*They allow for internal expansion of organs
What are the 2 layers in sutural bone growth?
1. Inner cambian layer associated with periosteum
2. Outer capsular layers meet to join sutures together
What type of bone growth allows flex to the skull as bone formation proceeds?
Sutural bone growth
What is the rate of bone turnover in children?
30-100% of their total bone per year
What is the rate of bone turnover in adults?
5% cortical and 15% trabecular per year
Most bone formation happens around the _____, while most bone resorption happens from the _______
Generally speaking, what does Bone remodeling and repair look like in cortical bone?
Primary osteons replaced by secondary osteons, which are replaced by tertiary osteons, allowing bone growth
What factors control bone remodeling and repair process?
Cascade of factors both cellular, systemic, and sequestered growth factors in bone matrix
What is the cutting cone vs. filling cone model of bone remodeling/repair
1. Osteoclasts resorb bone, leaving a space which is filled by trailing osteoblasts
2. Osteoblasts create a cement (non collagenous proteins) and lay new bone onto it