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Flashcards in chapter 7 (test 2) Deck (50):
1

osteology

the study of the bone

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skeletal system

bones, cartilage, and ligaments

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cartilage

covers many joint surfaces of adult bones

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ligaments

holds bones together at joints

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bones(osseous tissue)

connective tissue with matrix hardened by calcium phosphate and other minerals

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mineralization

hardening process of bone

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calcification

hardening process of bone

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lacunae

tiny cavities where the osteocytes

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canaliculi

little channels connecting lacunae

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skeleton function

support: holds up the body and muscles and teeth
protection: brain, spinal cord, heart and lungs
movement: limbs, breathing, action of muscle on bone
electrolyte balance: calcium and phosphate
acid-base balance: buffers blood against excess pH changes
blood formation: red bone marrow=chief blood cell producer

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ruffled border

side of a osteoclast facing the bone surface

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osteogenesis imperfecta

brittle bone disease (no collagen)

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rickets

disease where bone are easily bendable (no hydroxyapatite)

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interstitial growth

growth in length of the bones (stops early 20's)

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appositional growth

growth in width on the bones (continues all your life)

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ossification

formation of bone

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epiphyseal plate

growth zone on bones
region of transition from cartilage to bone

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metaphysis

zone of transition facing the marrow cavity

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epiphyseal line

place in adult bone where the epiphyseal plate once was

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circumferential lammellae

osteoclasts of endosteum increase marrow cavity

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bone remodeling

repairs microfractures, releases minerals into blood, and reshapes bone dues to use and misuse

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wolff's law of bone

architecture of bone determined by mechanical stresses placed on it & bones adapt to w/stand those stresses
-osteoblast and osteoclasts

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abnormal calcification

(ectopic calcification)
an unusually high deposit of calcium where it should not be
-occurs in the lungs, brain, eyes, muscles, tendons and arteries

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calculus

calcified mass in an otherwise soft organ

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orthopedics

deals with prevention and correction of injuries and disorders of bones, joints, and muscles

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stress fracture

breaks caused by abnormal trauma to bone

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pathological fracture

break in bone weakened by some other disease

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nondisplaced fracture

a break in the bone that stays lined up and in place

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displaced fracture

a break in the bone that is moved to one side or the other and is no longer in line

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comminuted fracture

bone broken into 3 or more pieces

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greenstick fracture

one part of the bone is broken while another part is only bent

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closed reduction

procedure in which bone fragments manipulated into their normal positions without surgery

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general features of Long bones

compact bone, diaphysis, medullary cavity, epiphyses, spongy bone, articular cartilage, nutrient foramina, endosteum, periosteum, epiphyseal plate

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bone cells

osteogenic cells
osteoblasts
osteocytes
osteoclasts

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osteogenic cells

stem cells in endosteum, periosteum, and central canals
-from embryonic mesenchymal cells; multiply rapidly--> new osteoblasts

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osteoblast

bone forming cells
-1 layer of cells under endosteum and periosteum
-nonmitotic
-synthesize soft organic matter of matrix
-stress and fractures(+) osteogenic cells to multiply faster and increase # of osteoblasts (reinforce or rebuild bone)

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osteocytes

osteoblasts trapped in matrix
lacunae- tiny cavities where osteocytes are
canaliculi- little channels connecting lacunae
-cytoplasmic processes reach into canaliculi
-some reabsorb bone matrix, others deposit

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osteoclasts

bone-dissolving cells
-bone marrow stem cells--> blood cells
-fusion of many stem cells--> multinucleated
-ruffled border: side facing bone surface
*deep infoldings: increase surface area and reabsorption efficiency
-remodeling: actions of osteoclasts and osteoblasts

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matrix

osseous tissue: 1/3 organic 2/3 inorganic
organic: synthesized by osteoblasts
-collagen
inorganic: 85% hydroxyapatite (Ca(PO3)4), 10% CaCO3, other minerals(F, Na, K, Mg)
poylmer-collagen
ceramic-hydoxyapatite

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compact bone

arranged in cylinders (concentric lamella) surrounding central canals running longitudinally through long bone shafts
-Blood vessels & nerves through central canal
-osteon: central canal and surrounding lamalae
-Canaliculi: canals coming from each lacuna to its neighbors & allow osteocytes to contact each other

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spongy bone

Consists of:
–Slivers of bone (spicules)
–Thin plates of bone (trabeculae)
–Spaces:
Few osteons & no central canals
–All osteocytes close to bone marrow

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Bone Marrow

soft tissue in marrow cavity and spaces of trabeculae
Red:
-Hemopoietic tissue: produces blood cells
-most of the bone marrow as kids, as adults only in the skull, vertebrae, ribs, sternum, part of pelvic girdle, humerus and femur
Yellow:
-Adults: red marrow turns to fatty yellow marrow
-no longer produces blood

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Intramembranous Ossification

1) Condensation of mesenchyme into soft sheet permeated with blood capillaries
2) Deposition of osteoid tissue by osteoblasts on mesenchymal surface; entrapment of first osteocytes; formation of periosteum
3) Honeycomb of bony trabeculae formed by continued mineral deposition; creation of spongy bone
4) Surface bone filled in by bone deposition, converting spongy bone to compact bone. Persistence of spongy bone in the middle layer
-Flat bones of skull and clavicle

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Endochondral Ossification

1) Early cartilage model: all hyaline cartilage
2) Formation of primary ossification center, bony collar and periosteum
3) vascular invasion, formation of primary marrow cavity, and appearance of secondary ossification center
4) Bone at birth, with enlarged primary marrow cavity and appearance of secondary marrow cavity in one epiphysis
5) Bone of child, with epiphyseal plate at distal end
6) Adult bone with a single marrow cavity and closed epiphyseal plate
-epiphyseal plate functions as growth zone
-most long bones

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Mineral Deposition

mineralization
-crystallization process where ions taken from blood plasma deposited in bone tissue
-osteoblasts: produce collagen fibers
-fibers covered with minerals= harden matrix

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Mineral Reabsorption

-dissolve bone and release minerals into blood
-osteoclasts at ruffled border
-H+ pumps in membranes
-Cl- ions follow
-HCl acid dissolves bone minerals
-acid phosphate enzyme digests collagen

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Hypocalcemia

Ca2+ deficiency
-wide variety of causes
-can be caused by: vitamin D deficiency, diarrhea, thyroid tumors, underactive parathyroids, pregnancy and lactation

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Ca2+ Homeostasis

balance between diatary intake, urinary and fecal losses and exchanges between osseous tissue
-3 hormones:
calcitriol (raises blood calcium levels)
calcitonin (lowers blood calcium levels)
parathyroid hormone (increases blood calcium levels)

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Healing of Fracture

1) Hematoma formation: hematoma is converted to granulation tissue by invation of cells and blood capillaries
2) Soft callus formation: deposition of collagen and fibrocartilage converts granulation tissue to a soft callus
3) Hard callus formation: Osteoblasts deposit a temporary bony collar around the fracture to unite the broken places while ossification occurs
4) Bone remodeling: small bone fragments are removed by osteoclasts, while osteoblasts deposit spongy bones and then convert it to compact bone

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Osteoporosis

severe loss of bone density
-bones lose mass and become brittle--> loss of organic matrix and minerals
--spongy bone is the most affected because it is most metabolically active
-estrogen maintains density in both sexes
-men: testes and adrenals produce estrogen
-women: rapid bone loss after menopause since ovaries cease to secrete estrogen