Term
| basic structure of skeletal cartilage |
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Definition
water lends resiliency
contains no blood vessels or nerves
perichondrium surrounds. all contain chondrocytes in lacunae and extracellular matrix |
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Term
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Definition
| dense connective tissue girdle. contains blood vessels for nutrient delivery. resists outward expansion |
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Term
| 3 types of skeletal cartilage |
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Definition
| hyaline, elastic, fibrocartilage |
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Term
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Definition
| provides support, flexibility, and resilience. collagen fibers only; most abundant type. articular, costal, respiratory, nasal cartilage |
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Term
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Definition
| similar to hyaline, but contains elastic fibers. external ear and epiglottis |
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Term
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Definition
| thick collagen fibers-has great tensile strength. menisci of the knee; vertebral discs |
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Term
| appositional growth of cartilage |
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Definition
| grows from the outside of the cartilage under the perichondrium. cells secrete matrix against external face of existing cartilage |
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Term
| interstitial growth of cartilage |
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Definition
| growth from the inside of the cartilage. chondrocytes divide and secrete new matrix, expanding cartilage from within. (less common) |
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Term
| calcification of cartilage |
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Definition
| occurs during normal bone growth (youth and old age). hardens, but calcified cartilage is not bone |
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Term
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Definition
| long (humerus), flat (sternum), short (talus), and irregular (vertebrae) |
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Term
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Definition
| longer than they are wide, limbs, wrists, ankle bones |
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Term
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Definition
| cube-shaped bones (in wrist and ankle). sesamoid bones (within tendons, eg. patella). vary in size and number in different individuals |
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Term
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Definition
| thin, flat, slightly curved. sternum, scapulae, ribs, most skull bones |
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Term
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Definition
| complicated shapes. vertebrae, coxal bones |
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Term
| 7 important functions of bones |
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Definition
| support, protection, movement, mineral and growth factor storage, blood cell formation, triglyceride (fat) storage, hormone production |
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Term
| support function of bones |
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Definition
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Term
| protection function of bones |
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Definition
| for brain, spinal cord, and vital organs |
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Term
| movement function for bones |
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Definition
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Term
| mineral and growth factor storage function for bones |
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Definition
| calcium and phosphorus, and growth factors resevoir |
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Term
| blood cell formation function in bones |
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Definition
| hematopoiesis in red marrow cavities of certain bones |
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Term
| triglyceride (fat) storage function in bones |
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Definition
| in bone cavities. energy source |
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Term
| hormone production function of bones |
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Definition
| osteocalcin- regulates bone formation. protects against obesity, glucose intolerance, diabetes mellitus |
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Term
| bones are organs because... |
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Definition
| they are made up of more than two types of tissues. bone (osseous) tissue, nervous tissue, cartilage, fibrous connective tissue, muscle and epithelial cells in its blood vessels |
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Term
| 3 levels of structural A&P |
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Definition
| gross anatomy, microscopic, chemical |
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Term
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Definition
compact bone- dense outer layer, smooth and solid.
spongy bone (cancellous or trabecular)- honey combof flat pieces of bone deep to compact called trabeculae |
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Term
| structure of short, irregular, and flat bones |
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Definition
| thin plates of spongy bone covered by compact bone. plates sandwiched between connective tissue membranes (periosteum and endosteum). no shafts or epiphyses. bone marrow throughout spongy bone; no marrow in cavity. hyaline cartilage covers articular surfaces |
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Term
| structure of a typical long bone |
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Definition
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Term
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Definition
tubular shaft forms long axis
compact bone surrounding medullary cavity |
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Term
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Definition
| bone ends. external compact bone; internal spongy bone. articular cartilage covers articular surfaces. between is epiphyseal line- remnant of childhood bone growth at epiphyseal plate |
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Term
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Definition
| white, double-layered membrane. covers external surfaces except joint surfaces. outer fibrous layer, inner osteogenic layer abuts bone. many nerve fibers and blood vessels. anchoring points for tendons and ligaments |
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Term
| outer fibrous layer of periosteum |
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Definition
| made of dense irregular connective tissue- sharpey's fibers secure to bone matrix |
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Term
| osteogenic layer that abuts bone in periosteum |
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Definition
| contains primitive stem cells-osteogenic cells |
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Term
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Definition
| delicate connective tissue (areolar) membrane covering internal bone surface. covers trabeculae of spongy bone. lines canals that pass through compact bone. contains osteogenic cells that can differentiate into other bone cells |
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Term
| hematopoietic tissue in bones |
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Definition
| make red bone marrow and blood cells. found within trabecular cavities of spongy bone and diploe of flat bones in adults. in children found in medullary cavities while still growing. |
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Term
| red bone marrow can be found where in newborns? |
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Definition
| medullary cavities and spongy bone |
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Term
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Definition
| the whole structure of spongy bone that consists of many trabeculae |
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Term
| where is red bone marrow found in adults? |
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Definition
| heads of femur and humerus only. |
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Term
| red marrow is most active where? |
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Definition
| in diploe of spongy bone and some irregular bones |
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Term
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Definition
| found in the medullary cavity of long bones and can convert into red marrow if neccessary |
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Term
| bone markings are important why? |
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Definition
| sites of muscle, ligament, and tendon attachment on external surfaces. joint surfaces. conduits for blood vessels and nerves. projections, depressions, openings |
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Term
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Definition
| most indicate stresses created by muscle pull or joint modifications. depressions or openings usually allow for nerves and blood vessels to pass through |
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Term
| microscopic anatomy of bone: 5 major cell types in bone tissue |
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Definition
| osteogenic cells, osteoblasts, osteocytes, bone lining cells, osteoclasts |
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Term
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Definition
| aka osteoprogenitor cells. mitotically active stem cellsin periosteum and endosteum. when stimulated differentiate into osteoblasts or bone lining cells. some persist as osteogenic cells |
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Term
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Definition
| bone-forming cells. secrete unmineralized bone matrix or osteoid that includes collagen and calcium-binding proteins (collagen=90% of bone protein). actively mitotic |
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Term
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Definition
| mature bone cells in lacunae. monitor and maintain bone matrix. act as a stress or strain sensors by responding to and communicating mechanical stimuli to osteoblasts and osteoclasts (cells that destroy the bone) so bone remodeling can occur |
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Term
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Definition
| flat cells on bone surfaces believed to help maintain matrix. on external bone surface called periosteal cells. lining internal surfaces called endosteal cells |
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Term
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Definition
| derived from hematopoietic stem cells that become macrophages. giant, multinucleate cells for bone resorption. |
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Term
| osteoclasts when active rest in resorption bay and have ruffled border |
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Definition
| ruffled border increases surface area for enzyme degradation of bone and seals off area from surrounding matrix |
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Term
| microscopic anatomy of compact bone |
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Definition
| aka lamellar bone. osteon or haversian system- structural unit of compact bone. elongated cylinder parallel to long axis of bone. hollow tubes of bone matrix called lamellae |
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Term
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Definition
| collagen fibers in adjacent rings run in different directions. withstands stress- resists twisting |
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Term
| canals and canaliculi of compact bone |
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Definition
| central (haversian) canal- runs through core of osteon. contains blood vessels and nerve fibers |
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Term
| perforating (Volkmann's) canals of compact bone |
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Definition
canals lined with endosteum at right angles to central canal.
connect blood vessels and nerves of periosteum, medullary cavity, and central canal |
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Term
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Definition
| small cavities that contain osteocytes |
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Term
| canaliculi of compact bone |
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Definition
| hair-like canals that connect lacunae to each other and central canal |
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Term
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Definition
osteoblasts secreting bone matrix maintain contact with each other and osteocytes via cell projections with gap junctions.
when matrix hardens and cells are trapped the canaliculi form. (allows communication, permits nutrients and wastes to be relayed from one osteocyte to another throughout osteon) |
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Term
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Definition
incomplete lamellae not part of complete osteon
fill gaps between forming osteons
remnants of osteons cut by bone remodeling |
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Term
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Definition
just deep to periosteum
superficial to endosteum
extend around entire surface of diaphysis
resists twisting of long bone |
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Term
| microscopic anatomy of spongy bone |
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Definition
| appears poorly organized and made up of trabeculae |
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Term
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Definition
align along lines of stress to help resist it
no osteons
contain irregularly arranged lamellae and osteocytes interconnected by canaliculi
capillaries in endosteum supply nutrients |
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Term
| chemical composition of bone: organic compounds |
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Definition
includes cells and osteod- matrix.
osteogenic cells, osteoblasts, osteocytes, bone-lining cells, and osteoclasts.
osteoid- 1/3 of organic bone matrix secreted by osteoblasts |
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Term
| osteoid is made out of... |
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Definition
made of ground substance (proteoglycans and glycoproteins)
collagen fibers
contributes to structure; provides tensile strength and flexibility |
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Term
| resilience of bone due to... |
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Definition
sacrificial bonds in or between collagen molecules.
stretch and break easily on impact to dissipate energy and prevent fracture
if no additional trauma, bonds reform |
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Term
| inorganic compounds of bone |
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Definition
hydroxyapatites (mineral salts).
65% of bone by mass
mainly of tiny calcium phosphate crystals in and around collagen fibers
responsible for hardness and resistance to compression |
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Term
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Definition
1/2 as strong as steel in resisting compression
as strong as steel in resisting tension
lasts long after death because of mineral composition (reveals info about ancient people)
can display growth arrest lines (horizontal lines on bones)... proof of illness- when bones stop growing so nutrients can help fight disease |
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Term
| ossification (osteogenesis) |
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Definition
| process of bone tissue formation. formation of bone skeleton (begins in 2nd month of development). postnatal bone growth (until early childhood). bone remodeling and repair (lifelong) |
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Term
| endochondral ossification |
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Definition
bone forms by replacing hyaline cartilage.
bones called cartilage (endochondral) bones.
forms most of the skeleton
begins late in 2nd month of development
uses hyaline cartilage models
requires breakdown of hyaline cartilage prior to ossification |
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Term
| intramembranous ossification |
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Definition
bone develops from fibrous membrane.
bones called membrane bones
forms flat bones (clavicles and flat bones) |
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Term
| endochondrial ossification begins at... |
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Definition
primary ossification center of shaft.
blood vessel infiltration of perichondrium converts it to periosteum-->underlying cells change to osteoblasts |
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Term
| steps of endochondrial ossification |
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Definition
primary ossification center forms
bone collar forms around diaphysis of cartilage model
central cartilage in diaphysis calcifies, then develops cavities
periosteal bud invades cavities-->formation of spongy bone
diaphysis elongates & medullary cavity forms
epiphyses ossify |
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Term
| intramembranous ossification begins within |
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Definition
fibrous connective tissue membranes formed by mesenchymal cells
ossification centers appear
osteoid is secreted
woven bone and periosteum form
lamellar bone replaces woven bone & red marrow appears |
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Term
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Definition
interstitial (longitudinal) growth (increasing in length of long bones)
appositional growth (increase in bone thickness) |
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Term
| interstitial growth (in length) of long bones |
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Definition
requires presence of epiphyseal cartilage
epiphyseal plate maintains constant thickness (rate of cartilage growth on one side balanced by bone replacement on other)
concurrent remodeling of epiphyseal ends to maintain proportion
result of 5 zones within cartilage |
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Term
| 5 zones within cartilage during interstitial growth |
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Definition
resting (quiescent) zone
proliferation (growth) zone
hypertrophic zone
calcification zone
ossification (osteogenic) zone |
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Term
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Definition
cartilage on epiphyseal side of epiphyseal plate
relatively inactive |
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Term
| proliferation (growth) zone |
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Definition
cartilage on diaphysis side of epiphyseal plate
rapidly divide pushing epiphysis away from diaphysis-->lengthening |
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Term
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Definition
| older chondrocytes closer to diaphysis and their lacunae enlarge and erode--> interconnecting spaces |
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Term
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Definition
| surrounding cartilage matrix calcifies, chondrocytes die and deteriorate. WEAKEST ZONE IN INTERSTITIAL GROWTH |
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Term
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Definition
chondrocyte deterioration leaves long spicules of calcified cartilage at epiphysis-diaphysis junction
spicules eroded by osteoclasts
covered with new bone by osteoblasts
ultimately replaced with spongy bone |
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Term
| end of interstitial growth of long bones |
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Definition
near end of adolescence chondroblasts divide less often
epiphyseal plate thins then is replaced by bone
epiphyseal plate closes |
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Term
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Definition
bone lengthening ceases (requires presence of cartilage)
bone of epiphysis and diaphysis fuses
females- about 18 years
males- about 21 years
human growth hormone is what causes bone growth |
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Term
| appositional growth (width) |
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Definition
allows lengthening bone to widen
occurs throughout life
osteoblasts beneath periosteum secrete bone matrix on external bone
osteoclasts remove bone on endosteal surface
usuall more building up than breaking down (thicker, stronger bone but not too heavy) |
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Term
| hormonal regulation of bone growth |
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Definition
growth hormone- most important in stimulating epiphyseal plate activity in infancy and childhood
thyroid hormone- modulates activity of growth hormone and ensures proper proportions
testosterone (males) and estrogen (females) at puberty- promote adolescent growth spurts and end growth by inducing epiphyseal plate closure
excesses or deficits of any cause abnormal skeletal growth |
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Term
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Definition
recycle 5-7% of bone mass each week- spongy bone replaced ~ every 3-4 years. compact bone replaced ~ every 10 years
older bone becomes more brittle- calcium salts crystalize. fractures more easily.
consists of bone remodeling and bone repair |
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Term
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Definition
consists of both bone deposit and bone resorption
occurs at surfaces of both periosteum and endosteum
remodeling units- adjacent osteoblasts and osteoclasts |
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Term
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Definition
evidence of new matrix deposit by osteoblasts- osteoid seam (unmineralized band of bone matrix) and calcification front (abrupt transition zone between osteoid seam and older mineralized bone).
trigger not confirmed- mechanical signals involved. endosteal cavity concentrations of calcium and phosphate ions for hydroxyapatite formation. matrix proteins bind and concentrate calcium. enzyme alkaline phosphatase for mineralization |
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Term
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Definition
done by osteoclasts- dig depressions or grooves as break down matrix. secrete lysosomal enzymes that digest matrix and protons. acidity converts calcium salts to soluble forms.
osteoclasts also phagocytize demineralized matrix and dead osteocytes (transcytosis will allow release into interstitial fluid and then into blood). once resorption complete, osteoclasts undergo apoptosis (kill themselves).
osteoclast activation involves PTH (para thyroid hormone) and T cell-secreted proteins |
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Term
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Definition
occurs continuously but regulated by genetic factors and 2 control loops-
negative feedback hormonal loop for Ca2+ homeostasis (controls blood calcium levels, not bone integrity)
responses to mechanical and gravitational forces |
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Term
| why is calcium so important to the body? |
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Definition
functions in- nerve impulse transmission, muscle contraction, blood coagulation, secretion by glands and nerve cells, cell division.
1200-1400 grams of calcium in body- 99% as bone minerals. amount in blood tightly regulated (9-11 mg/dl).
intestinal absorption requires vitamin D metabolites.
dietary intake required. |
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Term
| hormonal control of blood calcium levels |
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Definition
parathyroid hormone (PTH)- breaks bone down to put calcium in blood, regardless of bone integrity. produced by parathyroid glands.
calcitonin- may be involved. produced by parafollicular cells of thyroid gland. in high doses lowers blood calcium levels temporarily. |
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Term
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Definition
even minute changes in blood calcium is dangerous-
severe neuromuscular problems (hyperexcitability when levels too low)(nonresponsiveness when levels too high)
hypercalcemia- sustained high blood calcium levels. deposits of calcium salts in blood vessels, kidneys can interfere with function (kidney stones) |
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Term
| other hormones affecting bone density |
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Definition
leptin- hormone released by adipose tissue. role in bone density regulation (inhibits osteoblasts in animals).
serotonin- neurotransmitter regulating mood and sleep. most made in gut. secreted into blood after eating (interferes with osteoclast activity. serotonin reuptake inhibitors like Prozac cause lower bone density) |
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Term
| bone homeostasis: response to mechanical stress |
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Definition
bones reflect stresses they encounter- long bones thickest midway along diaphysis where bending stresses greatest.
bones stressed when weight bears on them or muscles pull on them- usually off center so tends to bend bones. bending compresses on one side, stretches on the other |
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Term
| results of mechanical stressors: wolff's law |
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Definition
bones grow or remodel in response to demands placed on it.
explains: handedness (right or left handed) results in thicker and stronger bone of that upper limb. curved bones thickest where most likely to buckle. trabeculae form trusses along lines of stress. large, bony projections occur where heavy, active muscles attach. bones of fetus and bedridden are featureless |
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Term
| how mechanical stress causes remodeling |
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Definition
electrical signals produced by deforming bone may cause remodeling- compressed and stretched regions oppositely charged.
fluid flows within canaliculi appear to provide remodeling stimulus |
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Term
| results of hormonal and mechanical influences |
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Definition
hormonal controls determine whether and when remodeling occurs to changing blood calcium levels.
mechanical stress determines where remodeling occurs |
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Term
| 3 "either/or" fracture classifications |
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Definition
| position of bone ends after fracture (nondisplaced- ends retain normal position. displaced- ends out of normal alignment), completeness of break (complete- broken all the way through. incomplete- not broken all the way through), and whether skin is penetrated or not (open(compound)- skin is penetrated. closed (simple)- skin is not penetrated |
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Term
| bone repair happens when... |
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Definition
| you fracture a bone or break the bone. in youth- most result from trauma. in old age- most result from weakness from bone thinning |
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Term
| bone fractures can also be classified by... |
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Definition
| described by location of fracture. external appearance. nature of break. - |
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Term
| how long does it take to fully repair a broken bone back to its original state? |
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Definition
| 3-9 months more bone lays in- medullary cavity expands |
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Term
| fracture treatment and repair |
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Definition
reduction- realignment of broken bone ends. closed reduction- physician manipulates to correct position. open reduction- surgical pins or wires secure ends.
immobilization by cast or traction for healing. depends on break severity, bone broken, and age of patient |
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Term
| stages of bone repair: hematoma forms |
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Definition
torn blood vessels hemorrhage
clot (hematoma) forms under periosteum- huge blood clot
site swollen, painful, and inflamed |
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Term
| stages of bone repair: fibrocartilaginous callus forms |
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Definition
capillaries grow into hematoma
phagocytize cells clear debris
fibroblasts secrete collagen fibers to span break and connect broken ends
fibroblasts, cartilage, and osteogenic cells begin reconstruction (create cartilage matrix of repair tissue. osteoblasts form spongy bone within matrix).
mass of repair tissue called fibrocartilaginous callus |
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Term
| stages of bone repair: bony callus forms |
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Definition
within one weeks new trabeculae appear in fibrocartilaginous callus
callus converted to bony (hard) callus of spongy bone
~2 months later firm union forms |
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Term
| stages of bone repair: bone remodeling occurs |
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Definition
begins during bony callus formation
continues for several months
excess material on diaphysis exterior and within medullary cavity removed
compact bone laid down to reconstruct shaft walls
final structure resembles original because responds to same mechanical stressors |
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Term
| homeostatic imbalances in bone |
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Definition
| osteomalacia, rickets, and osteoporosis |
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Term
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Definition
bones poorly mineralized
calcium salts not adequate
soft, weak bones
pain upon bearing weight |
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Term
| rickets (osteomalacia of children) |
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Definition
bowed legs and other bone deformities
bone ends enlarged and abnormally long
caused by: vitamin D deficiency or insufficient dietary calcium |
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Term
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Definition
group of diseases
bone resorption outpaces deposit
spongy bone of spine and neck of femur most susceptible- vertebral and hip fractures common |
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Term
| risk factors for osteoporosis |
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Definition
most often aged, postmenopausal women- 30% 60-70 yrs of age; 70% by age 80. 30% Caucasian women will fracture bone because of it.
men to a lesser degree.
sex hormones maintain normal bone health and density- as secretion wanes with age osteoporosis can develop |
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Term
| additional risk factors for osteoporosis |
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Definition
petite body form
insufficient exercise to stress bones
diet poor in calcium and protein
smoking
hormone-related conditions such as hyperthyroidism, low blood levels of thyroid-stimulating hormone, and diabetes mellitus.
immobility
males with prostate cancer taking androgen-suppressing drugs |
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Term
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Definition
| traditional treatments of calcium, vitamin D supplements, weight-bearing exercise, hormone replacement therapy (slows bone loss, but does not reverse it. controversial due to increased risk of heart attack, stroke, and breast cancer. some take estrogenic compounds in soy as substitute) |
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Term
| new drugs for osteoporosis treatment |
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Definition
bisphosphonates- decrease osteoclast activity and number. partially reverse in spine.
selective estrogen receptor modulators- mimic estrogen without targeting breast and uterus.
statins- though for lowering cholesterol also increase bone mineral density
denosumab- monoclonal antibody. reduces fractures in men with prostate cancer. improves bone density in elderly |
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Term
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Definition
plenty of calcium in diet in early adulthood
reduce carbonated beverage and alcohol consumption- leaches minerals from bone so decreases bone density
plenty of weight-bearing exercise- increases bone mass above normal for buffer against age-related bone loss |
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Term
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Definition
excessive haphazard bone deposit and resorption- bone made fast and poorly (called pagetic bone). very high ratio of spongy bone to compact bone and reduced mineralization.
usually in spine, pelvis, femur, and skull.
rarely occurs before age 40.
cause is unknown- possibly viral
treatment includes calcitonin and bisphosphonates |
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Term
| developmental aspects of bones |
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Definition
embryonic skeleton ossifies predictably so fetal age easily determined from x-rays or sonograms.
most long bones begin ossifying by 8 weeks
primary ossification centers by 12 weeks
at birth, most long bones well ossified (except epiphyses)
at age 25 ~all bones completely ossified and skeletal growth ceases |
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Term
| age related changes in bone |
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Definition
children and adolescents- bone formation exceeds resorption
young adults- both in balance, males greater mass
bone density changes over lifetime largely determined by genetics- gene for vitamin D's cellular docking determines mass early in life and osteoporosis risk as age
bone mass, mineralization, and healing ability decrease with age beginning in 4th decade- except bones of skull. bone loss greater in whites and in females.
electrical stimulation; daily ultrasound treatments hasten repair |
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