Chapter 8: Bone Flashcards by nono bennafield

Provides solid support for the body, thoracic cavities, and encloses internal cavities containing bone marrow where blood cells are formed

Bone tissue

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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

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Found in lacunae between lamellae, with cytoplasmic processes in small canaliculi that extend into the matrix

Osteocytes

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Growing cells which synthesize and secrete the organic components of the matrix

Osteoblasts

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Giant, multinucleated cells involved in removing calcified bone matrix and remodeling bone tissue

Osteoclasts

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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

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The internal surface surrounding the marrow cavity; connective tissue containing osteogenic cells

Endosteum

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External surface lining of bones; connective tissue containing osteogenic cells

Periosteum

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Produce the organic components of bone matrix including type I collagen fibers, proteoglycans, and matricellular glycoproteins, such as osteonectin

Osteoblasts

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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

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Unique collagen-rich material, between the osteoblasts layer and the preexisting bone surface

Osteoid

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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+

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Long dendritic processes, surrounded by calcifying matrix - radiating from each lacuna

Canaliculi

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Osteoblasts also release membrane-enclosed _____ ______ rich in alkaline phosphatase and other enzymes whose activity raises the local concentration of phosphate ions

Matrix vesicles

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Matrix vesicles serve as a foci for the formation of ________ crystals, the 1st visible step in calcification

Hydroxyapatite

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Osteoblasts surrounded by the material secrete and then differentiate as _______

Osteocytes

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Osteocytes communicate with one another, nearby osteoblasts, and bone lining cells through ____ ______

Gap junctions

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Most abundant cells in bone

Osteocytes

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Very large, motile cells with multiple nuclei that are essential for matrix resorption during bone growth and remodeling

Osteoclasts

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Osteoclasts’ origin from the fusion of bone marrow-derived _______

Monocytes

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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)

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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

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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

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Around the ruffled boarder is a ring of _____, adhering the cell to the bone “microenvironment”

Actin

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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