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106 Cards in this Set

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functions of the skeleton
support, protection, movement, electrolyte balance, acid-base balance, blood formation
another name for bone
osseous tissue
calcification
hardening process of bones(mineralization)
shapes of bones
long bones, short bones, flat bones, irregular bones
shaft
(diaphysis) cylinder of compact bone
marrow cavity of the shaft
medullary cavity, is lined w/ endosteum(osteogenic cells and reticular connective tissue)
enlarged ends of bones
epiphyses, spongy bone covered by compact bone, is enlarged to strengthen joint and attach ligament
the joint surface of bones is____
covered w/ articular cartilage
nutrient foramen
blood vessles that penetrate bone
periosteum
outer fibrous layer of collagen, inner osteogenic layer of bone forming cells
endosteum
thin layer of reticular connective tissue and osteogenic cells
epiphyseal plate
growth plate
types of bone cells
osteogenic, osteoblasts, osteocytes, osteoclasts
bone matrix
dry weight, 1/3 organic, 2/3 inorganic matter
organic matter of bone matrix
collagen, glycosaminoglycans, proteoglycans, and glycoproteins
inorganic matter of bone matrix
85% hydroxyapatite, 10% calcium carbonate, 5% other minerals(fluoride, potassium, magnesium)
combination of organic and inorganic matter of bone matrix_____
provides for strength and resilience
minerals in bone matrix...
resist compression
collagen in bone matrix...
resists tension
osteon
basic structural unit of compact bone
cylinders of osteons are formed...
from layers(lamellae) of matrix around central canal(osteonic canal)
in osteons, collagen fibers...
alternate between right and left handed helices from lamella to lamella
canaliculi
tiny cell processes that allow osteocytes to connect to each other and their blood supply
perforating canals
Volklmann canals, vascular canals perpendicularly joining central canals
trabeculae
spongelike appearance formed by plates of bone called trabeculae
spaces of spongy bone filled w/
red bone marrow
trabeculae have few...
osteons or central canals(no osteocyte is far from blood of bone marrow)
the trabeculae provides...
strength w/ little wieght, develop along bone's lines of stress
bone marrow
soft tissue that occupies marrow cavity
this type of marrow is hemopoietic
red bone marrow
hemopoietic
produces blood cells
yellow bone marrow
fat at center, no longer produces blood
intramembranous ossification
condensation of mesenchyme into trabeculae
embryonic connective tissue
mesenchyme
during intramembranous ossification, osteoblasts on trabeculae...
lay down osteoid tissue(uncalcified bone)
during intramembranous ossification_______ is deposited in the matrix forming bony trabeculae of spongy bone
calcium phosphate
during intramembranous ossification, osteoclasts...
create marrow cavity and form compact bone at surface
during intramembranous ossification, surface mesenchyme...
produces periosteum
during endochondral ossification...
bone develops from pre-existing model, most bones develop this process, formation of primary ossification center and marrow cavity in shaft of model
during primary ossification of endochondral ossification
bony collar is developed by osteoblasts, chondrocytes swell and die, stem cells give rise to osteoblasts and clasts, bone is laid down and marrow cavity is created
the secondary ossification centers and marrow cavities of endochondral ossification
form in ends of bone through same process as primary ossification centers
the secondary ossification centers and marrow cavities of endochondral ossification cartilage...
remains as articular cartilage and epiphyseal growth plates
growth plates
provide for increase in length of bone during childhood and adolescence
by early twenties, growth plates...
are gone and primary and secondary marrow cavities are united
zone of reserve cartilage(bone elongation)
hyaline cartilage
zone of proliferation(bone elongation)
chondrocytes multiply forming columns of flat lacunae
zone of hypertrophy(bone elongation)
cell enlargement
zone of calcification(bone elongation)
mineralization of matrix
zone of bone deposition(bone elongation)
chondrocytes die and columns fill w/ osteoblasts, osteons formed and spongy bone is created
during bone growth and remodeling...
bones increase in length, bones increase in width(appositional growth)
bones are remodeled...
throughout life
bones increase in length by...
interstitial growth of epipyseal plate, epipyseal line is left behind when cartilage is gone
when bones increase in width...
osteoblasts lay down matrix in layers on outer surface and osteoclasts dissolve bone on inner surface
Wolff's law of bone
architecture of bone is determined by mechanical stresses(action of osteoblasts and osteoclasts)
mineralization is a....
crystallization process
during mineralization
osteoblasts produce collagen fibers spiraled the length of the osteon, minerals cover the fibers and harden the matrix
when minerals cover the fibers and harden the matrix...
ions are deposited along the fibers; ion concentration must reach the solubility product for crystal formation to occur
abnormal calcification
(ectopic) may occur in lungs, brain, eyes, muscles, tendons or arteries(arteriosclerosis)
during mineral resorption from bone...
bone is dissolved and minerals are released into the blood
when bone is dissolved and minerals are released into the blood...
performed by osteoclasts(ruffled border), hydrogen pumps in membrane secrete hydrogen into space between the osteoclast and bone surface, chloride ions follow by electrical attraction, hydrochloric acid dissolves bone minerals, enzyme digest the collagen
dental braces reposition teeth and remodel bone
create more pressure on one side of the tooth, stimulates osteoclasts to remove bone, decreased pressure stimulates osteoblasts
Phosphate is a component of ...
DNA, RNA, ATP, phospholipids, and pH buffers
how much phosphate in adult skeleton
750g
plasma concentration of phospate
4 mg per dL
calcium is needed in ...
neurons, muscle contraciton, blood clotting and exocytosis
how much calcium in adult skeleton
1100g
plasma concentration of calcium
10mg per dL
ion imbalances in the bones are caused through...
changes in phosphate levels(little effect) and changes in calcium levels(can be serious)
hypocalcemia
deficiency of blood calcium, causes excitability of nervous system if too low(muscle spasms, tremors)
hypercalcemia
excess of blood calcium, binding to cell surface makes sodium channels less likely to open, depressing nervous system(muscle weakness and sluggish reflexes)
calcium phosphate homestasis...
depends on calcitriol, calcitonin, and PTH hormone regulation
carpopedal spasm
hypocalcemia demonstrated by muscle spasm of hands and feet
calcitriol, PTH, and calcitonin...
maintain normal blood calcium concentration
calcitriol
activated vitamin D, behaves as a hormone that raises blood calcium concentration
calcitriol is produced by the following process
UV radiation and epidermal keratinocytes convert steroid derivative to cholecalciferol(D3), liver converts it to calcidiol, kidney converts that to calcitriol(Vitamin D)
calcitriol behaves as a gromone that raises blood calcium concerntration by....
increasing intestinal absorption and absorption from the skeleton, increases stem cell differentiation into osteoclasts, promotes urinary reabsorption of calcium ions
lack of calcitriol causes...
abnormal softness(rickets) in children and osteomalacia in adults
calcitonin
secreted(C cells of thyroid gland) when calcium concentration rises too high
functions of calcitonin
reduces osteoclast activity as much as 70%, increases the number and activity of osteoblasts, reduces bone loss in osteoporosis
calcitonin is important in children
because osteoclasts are more active in children
deficiency of calcitonin does not
cause disease in adults
Parathyroid hormone
released w/ low calcium blood levels, glands located on posterior surface of thyroid
function of PTH
causes osteoblasts to release osteoclast-stimulating factor(RANKL) increasing osteoclast population, promotes calcium resorption by the kidneys, promotes calcitriol synthesis in the kidneys, inhibits collagen synthesis and bone deposition by osteoblasts
sporatic injection of low levels of PTH
causes bone deposition
other factors affecting bones
hormones, vitamins, growth factors
bone growth is_____during puberty and stops when_______ closes
rapid, epiphyseal plate
during the growth rate at puberty
hormones stimulate osteogenic cells, chondrocytes, and matrix deposition in growth plate
teenage use of anabolic steroids causes
premature closure of growth plate and short adult stature
pathological bone fracture
in bone weakened by disease(osteoporosis, bone cancer)
types of bone fractures
open, greenstick, comminuted, linear, transverse, oblique, spiral, colles, pott
healing time of fractures
8-12 weeks in normal adults
stages of bone healing
fracure hematoma, soft callus, hard callus, remodeling
fracture hematoma
clot forms, then osteogenic cells form granulation tissue
soft callus
fibroblasts produce fibers and fibrocartilage
hard callus
osteoblasts produce a bony collar in 6 weeks
remodeling
spongy bone replaced by compact bone
closed reduction
fragments are aligned w/ manipulation and casted
open reduction
surgical exposure and repair w/ plates and screws
electrical stimulation used on fractures...
if 2 months necessary for healing
orthopedics
prevention and correction of injuries and disorders of the bones, joints, and muscles
osteoporosis
bones lose mass and become brittle(loss of organic matrix and minerals), risk of fracture, pneumonia, blood clotting
greatest risk to osteoporosis
menopausal white women
osteogenic cells
stem cells that develop from fibroblasts and then give rise to other bone cells
osteoblasts
bone forming cells
osteocytes
former osteoblasts that have become trapped in the matrix they deposited
osteoclasts
bone dissolving cells found on the bone surface