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115 Cards in this Set
- Front
- Back
In which bones would red bone marrow be found? (5)
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1) Ileum (Hip)
2) Ribs 3) Sternum 4) Vertebrae 5) Metaphysis and epiphysis of long bones |
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In a newborn all bone marrow is ______________ and involved in ______________?
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Red, hematopoiesis
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Long Bone:
The bone's long shaft or body. Located in between the two metaphyses? |
Diaphysis
-General compact (cortical) bone |
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Long Bone:
The most proximal and distal portions of a bone? |
Epiphyses
-Generally spongy bone Note: This is technically an apophysis until the bone stops growing and it fuses. |
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Long Bone:
Regions between the diaphysis and epiphysis of a long bone? |
Metaphysis
-Generally spongy bone |
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Long bone:
Layer of hyaline cartilage in the metaphysis of a growing bone that allows the diaphysis of the bone to grow in length? |
Epiphyseal plate (Growth Plate)
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Normal developmental outgrowth of a bone which arises from another ossification center?
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Apophysis
Note: Fuses to bone later in development Note: Usually serves as an important insertion point for a tendon or ligament |
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Fracture that occurs through a growth plate?
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Salter Harris fracture
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Structure left by completely ossified epiphyseal plate?
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Epiphyseal line (synostosis)
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Thin layer of hyaline cartilage covering the part of the epiphysis where the bone forms an articulation with another bone? What is its function?
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Articular cartilage
Function: 1) Reduce Friction 2) Shock Absorption |
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Which bone in the body has an epiphyseeal line that does not complete ossify?
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1st rib attached to sternum
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Surrounds the external bone surface wherever it is not covered by articular cartilage?
Note: Contains blood vessels, nerves, osteogenic cells, serves as an attachment point for tendons/ligaments, and assists in fracture repair. |
Periosteum
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The periosteum is composed of an outer ____________ layer and an inner _______________ layer?
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1) Fibrous
2) Osteogenic |
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What is the name of the fibers that connect the periosteum and the associated structures that are integrated with the periosteum to the underlying bone?
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Sharpey's fibers (perforating fibers)
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Sharpey's fibers are thick bundles of partially mineralized____________ fibers that extend from the extracellular bone matrix to the periosteum?
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collagen
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Hollow cylindrical space within the diaphysis that contains fatty yellow bone marrow in adults?
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Medullary cavity (marrow cavity)
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Thin layer of connective tissue that lines the internal bone facing the medullary cavity, Contains a single layer of cells and a small amount of connective tissues?
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Endosteum
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Most abundant mineral salt in bone?
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Calcium Phosphate
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What two compounds is hydroxyapatite composed of?
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Calcium phosphate and Calcium Hydroxide
Note: These and other minerals gives bone its hardness |
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Unspecialized stem cell (derived from mesenchyme) that undergo cell division to become osteoblasts?
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Osteogenic Cells (Osteoprogenitor cell)
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Three places where osteogenic cells are found?
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1) Inner portion of periosteum
2) Endosteum 3) Canals within bone that contain blood vessels |
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Bone building cells:
These cells synthesize and secrete collagen fibers and other organic components needed to build the extracellular matrix of bone tissue. They also initiate calcification? |
Osteoblasts
Note: Blast simply describes any connective tissue cell which is capable/currently of secreting extracellular matrix. |
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How does an osteoblast become an osteocyte?
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As an osteoblast surround themselves with extracellular matrix, they become trapped and then become osteocytes
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Main cells in bone tissue that have a role in maintaining the tissue, its daily metabolism, and calcium homeostasis (exchange of nutrients and waste with blood)?
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Osteocyte
Note: Cyte simply refers to any cell that maintains a tissue. |
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Do osteocytes or osteoblasts undergo cell division?
Osteogenic cell--------->Osteoblast-------------->Osteocyte |
No
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Cells that engage in bone resorption and contain lysosomal enzymes and acids necessary for bone resorption?
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Osteoclasts
Clast: This ending simply refers to any tissue that breaks down extracellular matrix |
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Where are osteoclasts mainly concentrated?
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Endosteum
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What are osteoclasts composed of?
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Fusion of up to 50 monocytes
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How would one describe the surface of an osteoclast membrane that faces the bone surface?
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Ruffled
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Two types of bone tissue?
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1) Compact (Dense)/(Cortical)
2) Spongy (Cancellous)/ (Trabecular) |
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Bone found beneath the periosteum of all bones and richly concentrated in the diaphysis?
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Compact bone
Note: This bone is harder to maintain |
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Canal's that lymphatic vessels, blood vessels, and nerves from the periosteum penetrate compact bone?
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Volkman's canals (Perforating canals)
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Canals that run longitudinally through the bone and serve as a conduit for the vessels and nerves from the volkman's canals?
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Central Canals
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Rings of calcified extracellular matrix that wrap around central canals?
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Concentric Lamellae
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Spaces between lamellae that contain osteocytes?
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Lacunae
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Small channels that radiate in all directions from the lacunae. They are filled with extracellular fluid?
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Canaliculi
Important: It is the canaliculi that forms channels that allow osteocytes to communicate and for exchange of cellular nutrient and waste throughout compact bone. Note: The projections of osteocytes run through canaliculi though typically we only see the lacunae and canaliculi on slides. Osteocyte is usually lost in preparation. |
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Neighboring osteocytes communicated via ___________ junctions?
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Gap
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The repeating units of compact bone and all of its components?
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Haversion systems (Osteons)
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Components of a haversion system (Osteon)? (6)
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1) Central (haversion) canal
2) Concentric lamellae 3) Lacunae 4) Lamellae 5) Osteocytes 6) Canaliculi |
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Osteons in compact bone are aligned in the same direction along lines of ______________?
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Stress
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What type of lamellae is stored in areas between haversion systems?
Note: These are fragments of older osteons that have been partially destroyed during remodeling or growth. |
Interstitial lamellae
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Lamellae that encircles the bones just beneath the periosteum?
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Circumferential lamellae
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The irregular lattice like arrangment of lamellae in spongy bone?
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Trabeculae
Note: Space in between may contain bone marrow and considerable vasculature |
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Components within each trabecula?
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1) Concentric lamellae
2) Osteocytes in lacunae 3) And canaliculi |
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Where is spongy bone found?
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1) Small layer around medullary cavity of diaphysis that is covered by compact bone
2) Major component inside flat, irregular, and short bones 3) Most epiphyses and metaphyses of long bones |
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Spongy bone is always covered by a layer of ______________ bone for protection?
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Compact
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How are the trabecula of spongy bones arranged in terms of the stress bones receive?
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1) Parallel to the axis of stress
2) Generally located more towards areas that receive force in many directions |
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Two main components of bone tissues?
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1) Cells
2) Mineralized extracellular matrix |
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Collagen makes up about _____________% of bone tissue
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90%
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Components of bone ground substance?
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1) Proteoglycans
2) Multiadhesive glycoproteins 3) Bone-specific, vitamin K dependent proteins 4) Growth factors and cytokines -Bone morphogenic proteins |
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Proteins that help bone capture and store calcium and stimulate remodeling of bone?
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Bone specific vitamin K dependent proteins
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Function of multi-adhesive glycoproteins?
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Binds bone cells (osteocytes) to collagen in mineralized matrix
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Function of bone morphogenic proteins?
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Induce bone formation (especially during development)
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All components of bone ECM are mineralized? T or F
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True
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Also known as woven bone, this is nonlamellar bone that has many cells randomly arranged, more ground substance, and are sometimes found in adult alveolar sockets or oral cavity?
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Immature bone
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Volkman's canals run __________________ to osteons?
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Perpendicular
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What supplies blood supply for trabecular bone?
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Volkman's canals
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Trabeculae are thin anastomsing ____________?
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Spicules
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What is ground bone often dyed with?
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India ink...............or air is allowed to be trapped inside
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Ground bone allows one to visualize periosteum? T or F
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False
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Decalcified bone allows one to visualize periosteum? T or F
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True
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Inactive cells that line the periosteum?
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Periosteal cells
Note: these are osteoprogenitor cells often called bone lining cells |
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Inactive cells that line the endosteum?
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Endosteal cells
Note: these are osteoprogenitor cells often called bone lining cells |
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Differentiation factor that triggers osteoprogenitor--------------->osetoblast?
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Core binding factor alpha-1 (CBFA-1)
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Histological characteristics of osteroprogenitor cells?
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1) Squamous/flat
2) Elongated or Oviod Nuclei 3) Found on periosteum and endosteum |
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Two main things osteoblasts secrete?
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1) Type I collagen
2) Bone matrix proteins |
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What types of bone matrix proteins do osteoblasts secrete?
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1) Osteocalcin/Osteonectin
2) Multiadhesvie Glycoproteins -Sialoproteins 3) Alkaline Phosphatase |
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What is the purpose of osteocalcin and osteonectin?
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Calcium binding proteins
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Purpose of alkaline phosphatases?
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Proteins that induce calcification by triggering hydroxyapatite aggregation
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Osteoblasts communicate with osteocytes via ________________ junctions?
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Gap junctions
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Histological characteristics of osteoblasts?
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1) Cuboidal or polygonal shaped
2) Basophilic cytoplasm |
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Three states of osteocytes?
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1) Quiescent
2) Formative 3) Resorptive |
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What is occuring during the formative period of osteocyte activity?
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Matrix is deposited
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Osteocytes are involved in the initial stages of bone remodeling and use what enzyme to help engage this activity?
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Matrix metalloproteases
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What is the function of bone lining cells?
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1) Maintenance and nutritional support for osteocytes
2) Regulate movement of calcium and phosphate 3) Ultimately can differentiate and become osteoblasts and then osteoclasts |
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Bone lining cells are connected to osteocytes via _____________ and communicate via gap junctions?
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Canaliculi
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Unmineralized matrix secreted by osteoblasts? Visualized as a thin pale staining matrix between osteoblasts and lamellae.
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Osteoid
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Which signalling pathway signals for the differentiation of monocytes into osteoclasts?
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Rank and Rank-L pathways
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What is the function of the drug osteoprotegenerin?
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Inhibits osteoclast formation
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Three distinct specialized regions of an activated osteoclast?
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1) Ruffled border
2) Clear Zone 3) Basolateral Region |
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Osteoclasts are always found on the _____________ side of bone?
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Endosteal
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Depressed region in bone created by an osteoclasts?
Note: This is where the osteoclast is located |
Howship's lacunae
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What do the ruffled borders of the osteoclast secrete that degrade collagen and bone matrix proteins?
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1) Cathespin K
2) Matrix Metalloproteinases 3) Acid via ATP dependent proton pump |
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What happens to the debris that is broken down by osteoclasts?
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Phagocytosed and exocytosed
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Which area of an osteoclast binds to a bone keeping the osteoclast bound to the howship's lacuna?
Note: Made of actin filaments and specialized proteins |
Clear Zone
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What is the end result of an osteoclast that is finished resorbing bone?
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Undergoes apoptosis
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Histological characteristics of an osteoclast?
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1) Large
2) Multinucleated 3) Ruffled border |
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Chronic abnormal bone remodeling disease that tends to affect the elderly?
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Paget's disease
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Are there usually symptoms with Paget's Disease?
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No, usually discovered when many fractures begin occurring.
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Two blood tests to determine whether one has Paget's disease?
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1) TRAP
2) Alkaline Phosphatase |
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What is TRAP in regards top osteoclasts?
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It is a marker of osteoclast activity
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Two RX treatments for Paget's disease?
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1) Calcitonin
2) Bisphosphonates |
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The methods of bone formation?
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1) Intramembranous ossification
2) Endochondral Ossification |
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Process of intramembranous ossification?
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1) Mesenchymal cells cluster and differentiate into osteoprogenitor cells
2) There is increased vascularization of surrounding connective tissues 3) Osteoprogenitor cells diffferentiate into osteoblasts when Core Binding Factor-1 arrives because of increased vascularization 4) Osteoblasts now secrete matrix until they are surrounded by it. Spicules are formed and the immature bone formed resembles spongy bone. 5) As osteoblasts secrete matrix and are surrounded by it, they become osteocytes 6) More osteoprogenitor cells are attracted. New osteoblasts lay down bone by appositional bone growth 7) This continues until the bone begins to resemble compact bone. Bone is still woven/immature 8) Eventually a thin layer of compact bone will be formed by remodeling spongy bone. 9) Mesenchyme condenses at periphery of the bone and develops into periosteum 10) More remodeling needed as bone becomes organized into organized compact bone. |
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Which bones undergo intramembanous ossification?
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1) Flat bones of skull, face, mandible, clavicle, cranial fontanelles
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Process of endochondral ossification?
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1) Mesenchymal stem cells differentiate into chrondroblasts.
2) Cartilage precursor matrix of hyalin cartilage is laid down (Type II Collagen). Surrounded by perichondrium. 3) Growth occurs both by interstitial (from within) and appositional growth (growth at outer surface). 4) Chondrocytes in mid region hypertrophy and attracts calcium. It begins to ossify. 5) As the cartilage ossifies chondrocytes die and form lacunae. This is called cavitation. 6) A nutrient artery penetrates the perichondrium in the mid region stimulating perichondrium to differentiate into osteoprogenitor cells 7) Periosteum forms and its osteoprogenitor cells differentiate into osteoblasts as blood flow now carries Core Binding Factor-1. Periosteum extends bud in to cavitation site and osteoblasts fill the site with spongy bone. 8) Osteoblasts secrete matrix and form a layer of bone on top of cartilage (mid region of bone) 9) Alkaline phosphatase from osteoblasts continues the process of calcification of cartilage matrix 10) Blood vessels penetrates and form hollows in cartilage matrix. This is now a primary ossification center. 11) Initial bony matrix laid down resembles spongy bone and is immature 12) The medulllary cavity forms as osteoclasts break down some of the newly formed spongy bone trabecula. 13) Secondary ossification centers develop at the epiphyses of bones as epiphyseal arteries enter the epiphyses. These centers develop at about the time primary ossifications centers are forming. 14) The secondary ossification centers will maintain a spongy bone matrix while the primary ossification centers will mostly become cortical bone 15) Hyaline cartilage that covered the epiphyses becomes articular cartilage 16) Articular cartilage will remain between the epiphyses and metaphyses (epiphyseal plate) |
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Four zones of epiphyseal growth plates?
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1) Zone of resting cartilage (Reserve zone)
2) Zone of proliferating cartilage 3) Zone of hypertrophic cartilage 4) Zone of calcified cartilage |
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Layer nearest the epiphysis that contains small scattered chondrocytes. Main role is to anchor epiphyseal plate to epiphysis?
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Zone of resting cartilage
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Zone that contains chondrocytes that undergo interstitial growth as they divide and secrete extracellular matrix?
Note: These chondrocytes are replicating in response to chondrocytes that dies as bone is added to the diaphysis. They look like stacks coins |
Zone of proliferating cartilage
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Zone that consists of large maturing chondrocytes arranged in columns that are secreting a lot of matrix and attracting calcium?
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Zone of hypertrophic cartilage
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Zone that consists mostly of dead chondrocytes (underwent apoptosis) and is ossified?
Note: This region becomes the new part of the diaphysis and/or epiphysis through the process of endochondryl ossification Note: Calcified cartilage is resorbed by osteoclasts and osteoblasts lay down new bone matrix. |
Zone of calcified cartilage
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Osteoblasts add new bone matrix to an osteon from the inside to the outside? T or F
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False, outside towards inside
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Steps in the process of mineralization of ECM?
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1) Calcium binds to osteocalcin and sialoproteins
2) Calcium causes osteoblasts to secrete alkaline phosphatase which attracts phosphates to area 3) Osteoblasts release further vesicles with alkaline phosphatase and pyrophosphate which cleave phosphates 4) Hydroxyapatite crystals form 5) Hydroxyapatite is deposited in an interlocking fashion |
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Hormone that stimulates osteoclasts activity?
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Parathyroid hormone
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Hormone that inhibits osteoclast activity?
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Calcitonin
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Type of fracture that breaks through the skin?
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Open fracture
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Type of fracture that does not penetrate the skin?
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Closed fracture
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Fracture in which bone is splintered/crushed leaving smaller bone fragments between the two main broken bone fragments?
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Communited fracture
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Partial fracture where one side of the bone is broken and the other side is bent?
Note: This happens in children whose bones are not fully ossified. They bones contain a considerable amount of organic vs. inorganic material making the bones more pliable. |
Greenstick fracture
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Fracture in which one end of a fractured bone is forcefully driven into the interior of the other end?
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Impacted fracture
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Fracture of the distal fibula?
Note: Causes serious injury of the distal tibial articulation |
Pott's fracture
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Fracture of the distal radius?
Note: Distal fragment is posteriorly displaced |
Colles fracture
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Steps in the process of fracture healing?
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1) Formation of a fracture hematoma
-Reduced blood flow -Bone cells in region die -Neutrophils and macrophages remove dead or damaged tissue -This could last for several weeks 2) Fibroblasts and capillaries from periosteum invade the fracture site and produce collagen fibers 3) Cells from periosteum differentiate into chondroblasts and produce fibrocartilage in the region -A fibrocartilaginous callus forms that bridges the gap between the two broken bones -Could take three weeks to form 4) Near areas close to well vascularized bone tissue, osteogenic cells develop into osteoblasts which produce spongy bone trabeculae on outside surface of bones -This is the bony callus -This joins living and dead portions of bone fragments 5) Osteogenic buds invade fibrocartilagnious callus and replaces it with bone matrix 6) Bone is remodeled to appropriate content of compact and spongy bone through the action of osteoblasts and osteoclasts. |
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Where are most bone cancers localized/started? Why?
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In areas of red bone marrow because of vascularization
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