Chapter 8: Bone Flashcards
Provides solid support for the body, thoracic cavities, and encloses internal cavities containing bone marrow where blood cells are formed
Bone tissue
Serves as a reservoir of calcium, phosphate, and other ions that can be released or stored in a controlled fashion to maintain constant concentrations in body fluids
Bone(osseous) tissue
Found in lacunae between lamellae, with cytoplasmic processes in small canaliculi that extend into the matrix
Osteocytes
Growing cells which synthesize and secrete the organic components of the matrix
Osteoblasts
Giant, multinucleated cells involved in removing calcified bone matrix and remodeling bone tissue
Osteoclasts
B/c metabolites can’t diffuse thought calcified matrix of bone, the exchanges btw osteocytes and blood capillaries depend on communication through the very thin, cylindrical spaces of the ___________
Canaliculi
The internal surface surrounding the marrow cavity; connective tissue containing osteogenic cells
Endosteum
External surface lining of bones; connective tissue containing osteogenic cells
Periosteum
Produce the organic components of bone matrix including type I collagen fibers, proteoglycans, and matricellular glycoproteins, such as osteonectin
Osteoblasts
Active osteoblasts are located exclusively at the ________ of bone matrix, to which they are bound by ______, typically forming a single layer of _______ cells joined by ______ and ____ junctions
Surfaces; integrins; cubodial; adherent; gap
Unique collagen-rich material, between the osteoblasts layer and the preexisting bone surface
Osteoid
Prominent among the noncollagen proteins secreted by osteoblasts is the vitamin K-dependent polypeptide _________, which together with various glycoproteins binds _____ ions and concentrates this mineral locally
Osteocalcin; Ca2+
Long dendritic processes, surrounded by calcifying matrix - radiating from each lacuna
Canaliculi
Osteoblasts also release membrane-enclosed _____ ______ rich in alkaline phosphatase and other enzymes whose activity raises the local concentration of phosphate ions
Matrix vesicles
Matrix vesicles serve as a foci for the formation of ________ crystals, the 1st visible step in calcification
Hydroxyapatite
Osteoblasts surrounded by the material secrete and then differentiate as _______
Osteocytes
Osteocytes communicate with one another, nearby osteoblasts, and bone lining cells through ____ ______
Gap junctions
Most abundant cells in bone
Osteocytes
Very large, motile cells with multiple nuclei that are essential for matrix resorption during bone growth and remodeling
Osteoclasts
Osteoclasts’ origin from the fusion of bone marrow-derived _______
Monocytes
Osteoclast development requires two polypeptides produced by osteoblasts: ________ and the __________
M-CSF (macrophage-colony-stimulating factor) and RANKL(receptor activator of nuclear factor-kB ligand)
In areas of bone undergoing resorption, osteoclasts on the bone surface lie within enzymatically etched depressions or cavities in the matrix known as _____ ______
Howship lacunae
In active osteoclasts, the membrane domain that contacts the bone forms a circular ____ ____ that binds the cell tightly to the bone matrix and surrounds an area with many surface projections, called the ____ _____
Sealing zone; ruffled border
Around the ruffled boarder is a ring of _____, adhering the cell to the bone “microenvironment”
Actin
Osteoclast pumps ____ to acidify and promote dissolution of the adjacent hydroxyapatite
Protons
Breakdown organic components
Collagenases
Most abundant inorganic material in the bone matrix
Calcium-hydroxyapatite
The organic matter embedded in the calcified matrix is 90% ___ _ collagen, but also includes mostly small proteoglycans and multiadhesive glycoproteins such as _______
Type I; osteonectin
External surfaces of all bones are covered by connective tissue of the ______
Periosteum
Internal surfaces of all bones are covered by connective tissue of the ______
Endosteum
An outer fibrous layer of dense connective tissue, containing mostly bundled type I collagen, fibroblasts, and blood vessels
Periosteum
Bundles of periosteal collagen, that penetrate the bone matrix and bind the periosteum to the bone
Sharpey fibers
Mesenchymal stem cells located in the periosteum’s inner layer
Osteoprogenitor cells
Play prominent role in bone growth and repair; produce new osteoblasts
Osteoprogenitor cells
Densely packed osteons or parallel lamellae; thick, outer region (beneath periosteum) of bones
Compact (cortical) bone
Interconnected thin spicules or trabeculae covered endosteum; inner region of bones, adjacent to marrow cavities
Cancellous (trabecular or spongy) bone
In long bones, the bulbous ends called ________ are composed of _____ bone covered by a thin layer of _____ bone
Epiphyses; cancellous; compact
Bone organization with matrix existing as discrete sheets
Lamellar bone
Bone organization, newly formed with randomly arranged components
Woven bone
Lamellar bone: Multiple layers either _____ circumferential or in _____ ____ around a central canal
Parallel; concentric rings
Another name for Haversian system
Osteon
The complex of concentric lamellae, surrounding a central canal that contains small blood vessels, nerves and endosteum
Osteon
Outer boundary of each Osteon is a layer called the _____ line that includes many more noncollagen proteins
Cement
How central canals communicate with one another using ____ _____
Volkmann canals
Numerous irregularly shaped groups of parallel lamellae; scattered among the intact osteons
Interstitial lamellae
Long bones have parallel lamellae organized as multiple _____ circumferential lamellae immediately beneath the periosteum and fewer _____ circumferential lamellae around the marrow cavity
External; inner
Nonlamellar and characterized by random disposition of type I collagen fibers
Woven bone
The first bone tissue to appear in embryonic development and in fracture repair
Woven bone
_______ ossification in 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 begin osteoid production
Endochondral
_____ bone is produced first and is soon replaced by stronger ______ bone
Woven; lamellar
Most flat bones - skull, jaws, scapula, and clavicle - are formed embryonically by __________ ossification
Intramembranous
Areas in which Osteoprogenitor cells arise, proliferate, and form incomplete layers of osteoblasts around a network of developing capillaries
Ossification centers
Areas in which Osteoprogenitor cells arise, proliferate, and form incomplete layers of osteoblasts around a network of developing capillaries
Ossification centers
________ ossification that takes place within hyaline cartilage
Endochondral
Ossification first occurs within a bone _____ produced by _______ that differentiate within the peri_______ around the cartilage model ________
Collar; osteoblasts; perichondrium; diaphysis
Step 2. The collar impedes diffusion of oxygen and nutrients into the underlying cartilage, causing local _________ to swell up (hypertrophy), compress the surrounding _______, and initiate its calcification by releasing ________ and alkaline phosphatase
Chondrocytes; matrix; osteocalcin
Step 3. After Chondrocytes die, one or more blood vessels from the peri______ penetrate the bone collar, bringing osteo__________ cells to the porous central region
Periosteum; Osteoprogenitor
Step 4. Newly formed ______ move into all available spaces and produce _____ bone
Osteoblasts; woven
The process in the diaphysis forms the ______ ossification center, beginning in many embryonic bones
Primary
Secondary ossification centers appear later at the ______ of the cartilage model
Epiphyses
Both the primary and secondary ossification centers produce cavities that are gradually filled with ____ _____ and ______ of cancellous bone
Bone marrow; trabeculae
With the primary and secondary ossification centers, two regions of cartilage remain: ______ cartilage and _______ plate/cartilage
Articular; epiphyseal
Connects each epiphysis to the dialysis and allows longitudinal bone growth
Epiphyseal plate/cartilage
Zone of ____ _____ is composed of typical hyaline cartilage
Resting cartilage
In the ______ zone, cartilage cells divide repeatedly, enlarge and secrete more type ___ collagen and proteoglycans, and become organized into columns _______ to the long axis of the bone
Proliferative; II; parallel
The zone of ______ contains swollen, terminally differentiated Chondrocytes, which compress the matrix and secrete collagen X which limits ________
Hypertrophy; diffusion
In the zone of ____ _____, chondrocytes about to undergo apoptosis release matrix vesicles and _______ to begin matrix calcification by the formation of ___________ crystals
Calcified cartilage; osteocalcin; hydroxyapatite
In the zone of _________, bone tissue first appears. Capillaries and _________ cells invade the now vacant chondrocytic ______
Ossification; Osteoprogenitor; lacunae
An example of bone ______ is the ability of the positions of teeth in the jawbone to be modified by the lateral pressures produced by orthodontic applications
Plasticity
Step 1. Blood vessels torn within the fracture release blood that ___ to produce a large fracture ______
Clots; hematoma
Step 2. The hematoma is gradually removed by ________ and replaced by soft _________-like mass called ______ tissue
Macrophages; fibrocartilage; procallus
Step 3. The fibrocartilage is gradually replaced by ______ bone that forms a hard _____
Woven; callus
Step 5. Woven bone is replaced by ______ bone
Lamellar
______ ______ raises low blood calcium levels by stimulating osteoclasts and osteocytes to resorb bone matrix and release Ca2+
Parathyroid hormone (PTH)
PTH receptor occur on _______, which respond by secreting RANKL and other paracrine factors that stimulate _______ formation and activity
Osteoblasts; osteoclast
________ reduce elevated blood calcium levels by targeting ______ to slow matrix resorption and bone turnover
Calcitonin; osteoclasts
