chapter 7 (test 2) Flashcards
osteology
the study of the bone
skeletal system
bones, cartilage, and ligaments
cartilage
covers many joint surfaces of adult bones
ligaments
holds bones together at joints
bones(osseous tissue)
connective tissue with matrix hardened by calcium phosphate and other minerals
mineralization
hardening process of bone
calcification
hardening process of bone
lacunae
tiny cavities where the osteocytes
canaliculi
little channels connecting lacunae
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
ruffled border
side of a osteoclast facing the bone surface
osteogenesis imperfecta
brittle bone disease (no collagen)
rickets
disease where bone are easily bendable (no hydroxyapatite)
interstitial growth
growth in length of the bones (stops early 20’s)
appositional growth
growth in width on the bones (continues all your life)
ossification
formation of bone
epiphyseal plate
growth zone on bones
region of transition from cartilage to bone
metaphysis
zone of transition facing the marrow cavity
epiphyseal line
place in adult bone where the epiphyseal plate once was
circumferential lammellae
osteoclasts of endosteum increase marrow cavity
bone remodeling
repairs microfractures, releases minerals into blood, and reshapes bone dues to use and misuse
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
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
calculus
calcified mass in an otherwise soft organ
orthopedics
deals with prevention and correction of injuries and disorders of bones, joints, and muscles
stress fracture
breaks caused by abnormal trauma to bone
pathological fracture
break in bone weakened by some other disease
nondisplaced fracture
a break in the bone that stays lined up and in place
displaced fracture
a break in the bone that is moved to one side or the other and is no longer in line
comminuted fracture
bone broken into 3 or more pieces
greenstick fracture
one part of the bone is broken while another part is only bent
closed reduction
procedure in which bone fragments manipulated into their normal positions without surgery
general features of Long bones
compact bone, diaphysis, medullary cavity, epiphyses, spongy bone, articular cartilage, nutrient foramina, endosteum, periosteum, epiphyseal plate
bone cells
osteogenic cells
osteoblasts
osteocytes
osteoclasts
osteogenic cells
stem cells in endosteum, periosteum, and central canals
-from embryonic mesenchymal cells; multiply rapidly–> new osteoblasts
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)
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
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
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
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
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
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
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
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
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
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
Hypocalcemia
Ca2+ deficiency
- wide variety of causes
- can be caused by: vitamin D deficiency, diarrhea, thyroid tumors, underactive parathyroids, pregnancy and lactation
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)
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
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
