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123 Cards in this Set
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skeletal cartilage |
cartilage molded to fit its body location and function; no nerves or blood vessels, fibers form a structural mesh
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perichondrium
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a layer of dense irregular connective tissue surrounding skeletal cartilage, resists outward expansion and contains blood vessels
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1. hyaline
2. elastic 3. fibrocartilage |
3 types of skeletal cartilages |
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hyaline cartilage |
cartilage with a glasslike extracellular matrix, provides support with flexibility and resilience; visible collagen fibers |
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– the ends of movable joints |
locations of hyaline cartilage |
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elastic cartilage
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cartilage with stretchy elastic fibers that allows for bending; contains collagen fibers and visible elastic fibers |
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– outer ear
– epiglottis |
locations of elastic cartilage |
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fibrocartilage
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highly compressible cartilage with great tensile strength; contains thick and visible collagen fibers
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– intervertebral discs
– menisci (knees, jaw) |
locations of fibrocartilage
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1. appositional growth
2. interstitial growth |
2 forms of cartilage growth |
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appositional growth
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form of cartilage growth in which chondrocytes of the perichondrium secrete new matrix against the external face of the existing cartilage tissue
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interstitial growth
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form of cartilage growth in which the chondrocytes divide and secrete new matrix, expanding the cartilage from within
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206
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# of bones in the human body
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1. axial
2. appendicular |
2 main groups of the skeleton
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1. support
2. protection 3. movement 4. hematopoiesis 5. hormone production 6. mineral and growth factor storage 7. fat storage |
7 important functions of bone
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hematopoiesis
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blood cell formation
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1. calcium
2. phosphate |
2 important minerals stored in bone matrix
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compact bone
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smooth and dense external layer of a bone
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spongy bone
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trabeculae–lined internal layer of a bone
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trabeculae
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small needle–like or flat pieces that form the honeycomb shape in spongy bone; open spaces filled with bone marrow
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diploë |
the sandwich–like spongy bone of short, flat, and irregular bones
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diaphysis
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the long, tube–shaped shaft of a long bone; compact bone surrounding a central medullary cavity |
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medullary cavity
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central cavity of the diaphysis containing fat (yellow marrow); called the yellow marrow cavity in adults
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epiphyses
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the broad ends of long bones
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articular cartilage
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covers the ends of the epiphyses, cushions the opposing ends of bones during movement and absorbs stress
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epiphyseal line
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remnant of the epiphyseal plate
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epiphyseal plate
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a hyaline cartilage disc separating the diaphysis and each epiphysis that grows during childhood and lengthens the bone
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1. periosteum
2. endosteum |
2 membranes covering a bone
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periosteum
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a glistening white, double–layered membrane covering the external surface of a bone; provides nutrition to the bone
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1. fibrous layer
2. osteogenic layer |
2 layers of the periosteum
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fibrous layer
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outer layer of the periosteum; dense irregular connective tissue
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osteogenic layer
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inner layer of the periosteum; contains osteogenic cells
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nutrient foramina
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openings in the periosteum that allow nerve fibers and blood vessels to pass through the bone shaft to the marrow cavity
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Sharpey's fibers (perforating fibers)
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collagen fibers that secure the periosteum to the underlying bone matrix
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endosteum
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a delicate connective tissue membrane covering the internal surface of bones
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red marrow
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hematopoietic tissue found within the trabecular cavities of spongy bone (long bones) and in the diploe (flat bones)
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red marrow cavities
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cavities that house hematopoietic tissue
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1. trabecular cavities (long bones)
2. diploë |
2 types of red marrow cavities
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bone markings
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projections, depressions, and openings on bone surfaces that serve as sites of muscle, ligament, and tendon attachment, as joint surfaces, or as conduits for blood vessels and nerves
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1. attachment (muscles, ligaments, tendons) |
3 functions of bone markings |
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1. osteogenic cells
2. osteoblasts 3. osteocytes 4. bone lining cells 5. osteoclasts |
5 major cell types in bone |
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osteogenic cells (osteoprogenitor cells) |
active stem cells found in the periosteum and endosteum; become osteoblasts or bone lining cells |
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osteoblasts
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bone–forming cells that secrete the bone matrix
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osteocytes
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mature bone cells that monitor and maintain the bone matrix; spidery cells that occupy spaces (lacunae) that conform to their shape
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bone lining cells
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flat cells that help maintain the bone matrix in areas where no remodeling occurs |
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1. periosteal cells
2. endosteal cells |
2 types of bone lining cells
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osteoclasts
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giant multinucleate cells with ruffled borders that break down bone with lysosomal enzymes |
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osteon (Haversian system)
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the cylinder–shaped structural unit of compact bone; tiny weight–bearing pillars
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lamella
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concentric rings of bone matrix making up an osteon (Haversian system) |
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central canal (Haversian canal)
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canal containing blood vessels and nerve fibers running through the core of each osteon
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perforating canal (Volkmann's canals)
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canals connecting the blood and nerve supply of the periosteum to the central canals and medullary cavity
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lacunae |
hollow spaces housing the spider–shaped osteocytes at the junctions of the lamellae |
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canaliculi
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hairlike canals connecting the lacunae to each other and to the central canal
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interstitial lamellae
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incomplete lamellae lying between intact osteons; fill gaps or are remnants of old osteons
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circumferential lamellae
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lamellae covering the entire circumference of the diaphysis; resist twisting of the long bone
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1. bone cells
2. osteoid |
2 organic components of bone (33%)
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osteoid
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organic part of bone matrix including ground substance and collagen fibers
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sacrificial bonds
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stretchy and breakable bonds between collagen molecules that can be reformed
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mineral salts (hydroxyapatites)
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inorganic component of bone (65%); tiny, tightly packed crystals surrounding collagen fibers in the bone matrix; account for a bone's hardness; ex. calcium phosphate
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ossification (osteogenesis)
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the process of bone formation
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1. endochondral ossification |
2 types of bone formation in a human embryo
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endochondral ossification
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bone developed by replacing hyaline cartilage; "cartilage bones", includes all bones below the base of the skull (except the clavicles) |
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Stage 1 of 5
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Endochondral Ossification: a bone collar forms around the diaphysis of the hyaline cartilage model
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Stage 2 of 5
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Endochondral Ossification: cartilage in the center of the diaphysis calcifies and cavities develop; chondrocytes die
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Stage 3 of 5
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Endochondral Ossification: the periosteal bud invades the internal cavities and spongy bone forms
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Stage 4 of 5
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Endochondral Ossification: the diaphysis elongates and a medullary cavity forms, osteoclasts break down spongy bone
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Stage 5 of 5
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Endochondral Ossification: the epiphyses ossify |
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primary ossification center |
the center of a hyaline cartilage shaft where long bone formation typically begins
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periosteal bud
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collection of elements that invade a newly forming bone (nutrient artery and vein, nerve fibers, red marrow elements, osteogenic cells, and osteoclasts)
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secondary ossification center
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the centers where bone is created from cartilage in one or both epiphyses |
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intramembranous ossification
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a bone develops from a fibrous membrane; membrane bone, includes the cranial bones and the clavicles |
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mesenchymal cells
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cells responsible for bone development in intramembranous ossification
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Stage 1 of 4
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Intramembranous Ossification: ossification centers appear in the fibrous connective tissue membrane; mesenchymal cells become osteoblasts
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Stage 2 of 4
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Intramembranous Ossification: osteoblasts secrete osteoid within the fibrous membrane that calcifies
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Stage 3 of 4
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Intramembranous Ossification: woven bone and periosteum forms
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Stage 4 of 4
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Intramembranous Ossification: lamellar bone replaces woven bone, red marrow appears
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1. proliferation zone |
4 zones of bone growth
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proliferation zone |
Bone growth: area where cartilage cells undergo mitosis |
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hypertrophic zone |
Bone growth: area where older cartilage cells enlarge
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calcification zone
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Bone growth: area where matrix calcifies, cartilage cells die, blood vessels invade cavity |
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ossification zone |
Bone growth: area where new bone forms |
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epiphyseal plate closure
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the process of longitudinal bone growth ending when the epiphysis and diaphysis bones fuse |
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growth hormone
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hormone that stimulates epiphyseal plate activity; released by the anterior pituitary gland
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thyroid hormone
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hormone that regulates growth hormone so that the skeleton grows proportionally
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sex hormones
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hormones promoting growth spurts in adolescensce; masculinization or feminization; induce epiphyseal closure
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bone remodeling
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process of deposit and resorption of bone in the periosteum and endosteum
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1. bone deposit
2. bone resorption |
2 stages of bone remodeling
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1. osteoblasts (deposition)
2. osteoclasts (resorption) |
"remodeling units" that coordinate bone deposition and resorption
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1. hormonal controls
2. response to mechanical stress |
2 factors influencing bone remodeling
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1. nerve impulses
2. muscle contraction 3. blood coagulation 4. secretion |
4 reasons calcium is necessary
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parathyroid hormone (PTH)
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hormone that stimulates osteoclasts to resorb bone, releasing calcium into the blood
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calcitonin
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hormone that temporarily lowers calcium levels
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hypercalcemia
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condition resulting in undesirable calcium salt deposits in the blood vessels and kidneys
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leptin
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hormone released by adipose tissue that inhibits osteoblasts
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Wolff's Law
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law stating that a bone grows or remodels in response to the demands placed on it
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hormonal controls
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determine whether and when bone remodeling occurs, in response to changing blood calcium levels
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mechanical stress
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determines where remodeling occurs
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fracture
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term for broken bones
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nondisplaced fractures
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broken bone ends retain their normal position
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displaced fractures
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broken bone ends are out of normal alignment
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complete fracture
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bone is broken all the way through
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incomplete fracture
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bone is not broken all the way through
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open (compound) fracture
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broken bone penetrates the skin
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closed (simple) fracture |
broken bone does not penetrate the skin
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comminuted fracture
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bone fragments into three or more pieces; common in the elderly |
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compression fracture
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bone is crushed; common in porous bones |
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spiral fracture
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ragged break occuring when excessive twisting forces are applied to a bone; common in sports
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epiphyseal fracture
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epiphysis separates from the diaphysis along the epiphyseal plate; common when chondrocytes are dying and calcification of the matrix is occurring
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depressed fracture
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broken bone portion is pressed inward; common in skull fracture
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greenstick fracture
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bone breaks incompletely (only one side breaks); common in children
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closed (external) reduction
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the physician's hands coax the broken bone ends into position
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open (internal) reduction
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the broken bone ends are secured together surgically with pins or wires |
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Stage 1 of 4
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Bone repair: a hematoma forms
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Stage 2 of 4
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Bone repair: fibrocartilaginous callus forms
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Stage 3 of 4 |
Bone repair: bony callus forms
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Stage 4 of 4
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Bone repair: bone remodeling occurs
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hematoma
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mass of clotted blood
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fibrocartilaginous callus
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mass of repair tissue in a broken bone
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bony (hard) callus
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spongy bone that replaces the fibrocartilaginous callus in a broken bone
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osteomalacia
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includes a number of disorders in which bones are poorly mineralized, becoming soft and weak; caused by insufficient calcium or vitamin D
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rickets
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osteomalacia in children; much more severe
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osteoporosis
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a group of diseases in which bone resorption outpaces bone deposit; bones become fragile and porous
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Paget's disease
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disease characterized by haphazard bone deposit and resorption; too much spongy bone, not enough compact bone |
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