Chapter 8 Flashcards
This cell synthesizes organic components of the matrix
Osteoblasts
What are the cells of bone
Osteocytes, osteoblasts, osteoclasts
Cells that are multinucleated, giant cells involved in the resorption and remodeling of bone tissue
Osteoclasts
____________ is on the internal surface and the _______________ is on external surface both surround the bone cavity
Endosteum, Periosteum
A layer of new ( but not calcified) material called __________ between the osteoblast layer and the preexisting bone surface
Osteoid
A small, vitamin K- dependent polypeptide ________ which together with various glycoproteins binds Calcium ions and raises their concentration locally
Osteocalcin
These are rich Alkaline Phosphatase and other enzymes whose activity raises the local concentration of Phosphate ions
Matrix vesicles
____________ are enclosed singly within the lacunae that are regularly spaced throughout the mineralized matrix
Osteocytes
In transition from osteoblasts to osteocytes the cells extend many long ___________ processes, which also become surrounded by calcifying matrix.
Dendritic
Osteoclasts lie within these enzymatic ally etched depressions or activities I the matrix known as______________ or ________________
Resorption cavities, Howship Lacunae
There are two polypeptides produced by osteoblasts : Macrophage Colony Stimulating Factor or ___________ and the receptor activator of nuclear factor kB ligand called ___________
M-CSF, RANKL
Osteoblasts are activated by the _______________ hormone which slows Osteoblasts to release M-CSF and RANKL
Para-thyroid
A Bone specific multi adhesive glycoprotein
Osteonectin
Bundles of periosteal collagen fibers penetrate the bone matrix binding the periosteum to bone.
Perforating /Sharpey fibers
Mesenchymal stem cells found cellular layer in the inner region of the periosteum , has the potential to proliferate and differentiate into osteoblasts
Osteoprogenitor cells
Internally the very small_______ covers small trabeculae of bony matrix that project into the marrow cavities also contains osteoprogenitor cells, osteoblasts, and bone lining cells
Endosteum
Represents 80% of the total bone mass
Compact ( cortical) bone
Numerous interconnecting cavities , makes up about 20% of total bone mass
Cancellous ( trabecular or spongy) bone
The bulbous ends of long bones, are composed of spongy bone covered by a thin layer of compact bone
Epiphyses
The cylindrical part which is almost totally composed of compact bone, with a thin region of spongy bone
Diaphysis
The flat bones that form the calvaria ( skullcap) have two layers of compact bone called
Plates
Plates are separated by a thicker layer of spongy bone called
Diploe
There are two types of organization on bone tissue
Lamellar and woven
Found In most adults, and is in compact or cancellous, characterized by multiple layers of this calcified matrix, 3-7 micrometers thick
Lamellar bone
Refers to the complex of concentric lamellae surrounding a small central canal that contains blood vessels, nerves, loose connective tissue, and endosteum
An Osteon
What is another name for an Osteon?
Haversian system
The outer boundary of each Osteon is a more collagen rich layer called the
Cement line
The central canals communicate with the marrow cavity and the periosteum and with through transverse
Perforating canals
What is another name for perforating canals
Volkmann canals
Irregularly shaped groups of parallel lamellae remained from osteons partially destroyed by osteoclasts during growth and remodeling of bone
Interstitial lamellae
Lamellae located around the marrow cavity
Inner circumferential
Lamellae that are located immediately beneath the periosteum
External circumferential lamellae
Is continuous throughout life and involves a process of bone resorption and bone formation
Bone remodeling
Is nonlamellar and characterized by random disposition of type I collagen fibers and is the first bone tissue to appear in embryonic development and in fracture repair
Woven bone
Another name for bone development
Osteogenesis
I’m which osteoblasts differentiate directly from mesenchyme and begin secreting osteoid
Intramembranous ossification
In which a preexisting matrix of hyaline cartilage is eroded and invaded by osteoblasts, which then begin osteoid production
Endochondral ossification
Within the condensed layer of mesenchyme the starting points for bone formation are called
Ossification centers
Begins as early as the first trimester
Primary Ossification Center
Appear later at the epiphyses of cartilage model and develop in a similar manner
Secondary Ossification Center
Within joints and usually persists through adult life and does not contribute to bone growth
Articular cartilage
Specially organized cartilage which connects each epiphysis to the diaphysis, also responsible for the growth in length of the bone and disappears at adulthood
Epiphyseal cartilage or epiphyseal plate
What are the 5 zones in bone growth
Resting, proliferative, hypertrophic cartilage, calcified cartilage, ossification
What zone Consists of hyaline cartilage with typical chondrocytes
Resting zone
Which zone do Chondrocytes begin to divide rapidly and form columns of stacked cells parallel to the long axis of the bone
Proliferate zone
Which zone contains swollen degenerative chondrocytes whose cytoplasm has accumulated glycogen. This hyper trophy compresses the matrix into septa between the chondrocytes
Hypertrophic cartilage zone
What zone does the loss chondrocytes by apoptosis is accompanied by calcification of the septa of cartilage matrix by the formation of hydroxyapatite
Calcified cartilage zone
The zone where bone tissue first appears capillaries and osteoprogenitor cells originally from the periosteum invade the cavities left by the chondrocytes
Ossification zone
From parathyroid glands acts in bone to raise low blood calcium levels by stimulating osteoclasts and osteocytes to resorb matrix and Calcium
PTH ( Para-Thyroid Hormone)
Synthesized within the thyroid gland reduces of PTH in the bone. This hormone directly targets osteoclasts to slow matrix resorption and bone turnover
Calcitonin
The places where bone meet, or articulate allow at least the potential for bending or movement I’m that portion of the skeleton
Joints
Joints with very limited or no movement are classified as
Synarthroses
Freely mobile joints
Diarthroses
The lubricant filled in the joint cavity of Diarthroses
Synovial Fluid
In Diarthroses this is the tough fibrous capsule that encloses the joint cavity
Articular capsule
This specialized connective tissue that lines the capsule with folds extended into some areas of the joint cavity
Synovial membrane
Remove wear and tear debris from synovial fluid
Macrophage like Synovial cells
Produce hyaluronate that is moved in the synovial fluid with water from local capillaries forming the synovial that nourishes and lubricates the articular cartilage
Fibroblast-like Synovial cells
Allow limited vertebral mobility and consist of large pads of fibrocartilage that cushion adjacent vertebrae
Intervertebral discs
Part of the intervertebral joints has the external layer of dense connective tissue but is mainly composed of overlapping laminae of fibrocartilage in which collagen bundles are orthogonally arranged in adjacent layers
Annulus Fibrosus
Situated in the center of the annulus Fibrosus and allows each disc to function as a shock absorber within the vertebral column
Nucleus Pulposus
Are derived from blood monocytes and remove wear and tear debris from the synovial fluid
Macrophage-like Synovial cells ( Type A cells)
Produces abundant hyaluronan and other extracellular components
Fibroblastic synovial cells ( type B cells)
What are the histological features of woven bone ( newly calcified)
Irregular and random arrangement of cells and collagen; lightly calcified
What are the histological features of Lamellar bone ( remodeled from woven bone)
Parallel bundles of collagen in thin layers with regularly spaced spaced cells between; heavily calcified
What are the histological features of compact bone ( 80% of all lamellar bone)
Parallel lamellae or densely packed osteons, with interstitial lamellae
What are the histological features of cancellous bone (~20% of all lamellar bone)
Interconnected thin spicules or trabeculae covered by endosteum
What are the major locations of woven bone ( newly calcified)
Developing and growing bones; hard callus of bone fractures
What are the major locations of lamellar bone
All normal regions of adult bone
What are the major locations of compact bone
Thick, outer region ( beneath periosteum) of bones
What are the major locations of cancellous bone ( inner region of bones, adjacent to marrow cavities)
inner region of bones, adjacent to marrow cavities
What are the synonyms of woven bone
Immature bone; primary bone; bundle bone
What are the synonyms of lamellar bone
Mature bone; secondary bone
What are the synonyms of compact bone
Cortical bone
What are the synonyms of cancellous bone
Spongy bone; trabecular bone; medullary bone
A type of cancer that can develop in osteoprogenitor cells
Osteosarcoma
The network of dendritic processes extending from osteocytes acts as a sensor detecting
Mechanical stress
__________ of exercise or weightlessness experienced by astronauts leads to _____________________
Lack, decreased bone density
A genetic disease which is characterized by dense, heavy bones( marble bones) the osteoclasts lack ruffled borders and bone resorption is defective, results in overgrowth and thickening of bones, with obliteration of marrow cavities, depressing blood cell formation and causes anemia and loss of white blood cells
Osteopetrosis
Is a disease where there is an imbalance in the skeletal turnover so that bone resorption exceeds bone formation. Leads to calcium loss from bones and reduced bone mineral density ( BMD)
Osteoporosis
A disease in which the bone matrix does not calcify normally and the epiphyseal plate can become distorted by the normal strains of body weight and muscular activity
Rickets
Antibiotic _________ is a fluorescent molecule that binds newly deposited osteoid matrix during mineralization with high affinity and specifically labels new bone under the UV microscope
Tetracycline
The tetracycline procedure involves a bone biopsy from patients who have taken tetracycline from ____ to_____ days the distance between the fluorescent lamellae is proportional to the rate of appositional growth
11, 14
The tetracycline procedure is of diagnostic importance in such diseases as ____________ in which mineralization is impaired, and ___________ in which increased osteoclast activity results in removal of bone matrix and fibrous degeneration
Osteomalacia, Osteitis fibrosa cystica
