Skeletal Flashcards
during long bone growth what happens on the diaphyseal side?
cartilage is replaced by bone at the same rate
if pressure in bones causes electrial changes that increase activity of osteoblasts what does it mean if you have a broken bone and apply weight to it?
it can speed up the heeling process
what does PTH cause osteoblasts to release?
RANK ligand
what does circumferential lamellae do to the bone surface?
it makes it smooth
does increasing mechanical stress on bones increase or decrease osteoblast activity?
increases
what cell becomes more active when blood calcium levels are too high?
osteoblasts
what do blood vessels grow into during endochondral ossification?
the perichondrium
who does the acceleration of bone growth from reproductive organs happen sooner?
females
where are hairline fractures common?
in the skull
how is spongy bone arranged?
into trabeculae
what substance makes up a major portion of the bone?
hydroxyapatite
how much of the weight of bone do bone cells account for?
2%
what type of ossification forms the epiphysis of the clavicle?
endochonral
what does spongy bone contain?
trabeculae of bone oriented on lines of stress
what is the difference between intramembranous and endochondral ossification?
in intramembranous ossification, bone forms from preexisting connective tissue membranes and in endochondral ossification bone forms from a preexisting cartilage model
what type of cells can reabsorb bone?
osteoclasts
what is the epiphysis?
the part of the long bone that develops from a center of ossification distinct from that of the diaphysis
what is the process of events to create woven bone? (3) (COO)
1) Connective tissue membrane is formed
2) osteochondral progenitor cells become osteoblasts
3) osteoblasts produce woven bone
what does compact bone cover?
the spongy bone of the epiphysis
when someone is bedridden or paralyed (reduced stress on bones) what does that do for osteoblast activity?
it decreases, resulting in less bone density
where does cartilage grow in bone?
at the surface underneath the perichondrium or in the center
how is compact bone organized?
into osteons
what is the hollow space within the diaphysis of a long bone called?
the medullary cavity
what is used to produce bone in humans for the first time?
ossification
what attaches to the periosteum?
tendons and ligaments
what is another name for brittle bone disorder?
osteogenesis imperfecta
when is bone mass at its highest?
around age 30
what is an example of a short bone?
carpal or wrist bone or sesmoid
what do both methods, intramembranous and endochonral produce?
woven bone which is then remodeled into lamellar bone
what does calcitrol cause?
the gut to absortb more calcium
when cartilage grows at the surface underneath the perichondrium what is it called?
appositional growth
what is the most significant age related changes in the skeletal system?
the quality and quantity of bone matrix
what provides the bone from the periosteum?
blood vessels and nerves
since spongy bone has no osteons what does it also lack?
a central canal
what do blood vessels, osteoblasts and osteoclasts do during endochondrial ossification?
they penetrate the center to form the primary ossification center and woven bone
what is concentric lamellae?
circular layers of bone matrix that surround the central canal
what happens to the woven bone during bone repair?
it’s remodeled to make a strong repair
what happens to the chondrocytes in the center during endochondrial ossification?
they enlarge, calcify and die
what do osteoblasts form during appositional growth?
ridges around a periosteal blood vessel
after ossification forms woven bone, what takes place?
bone is then remodeled into lamellar bone
bone is broken into at lease 2 fragments
complete fracture
what is bone modeling done by?
BMUs of osteoblasts and osteoclasts
what factors affect bone growth? (3)
1) adequate nutrition
2) level of growth hormone and thyroid hormones
3) reproductive hormones
what are the ossification regions formed during early fetal development?
primary ossification centers
what does intramembranous ossification form? (3)
1) the flat bones of the skull
2) some facial bones
3) part of the clavicles and mandible
what happens to the hyaline cartilage during endochondral ossification?
it remains at the ends and in the epiphyseal plates
how is woven bone formed?
from ossicfication
how does cartilage often occur?
in thin plates or sheets
what forms between the ends of the bone during bone damage?
a cartilage callus
where are chondrocytes located within?
lacunae
what does compact bone have?
osteons parallel to lines of stress
what is the function of the red marrow?
site of blood cell production
what are bones classified by?
shape
does the removal of mechanical stress on bones increase or decrease osteoblast activity?
decreases
what does calcitonin do?
inhibits osteoclasts and causes the kidneys to excrete more calcium
what do osteoblasts do first?
secrete the organic part of the matrix (collagen)
hyaline cartilage that covers long bone
articular cartilage
how does long bone grow?
in length
what is the structure of spongy bone?
it’s strong and light
what does spongy bone have?
bone marrow around the trabeculae
when cartilage grows in the center what is it called?
interstitial growth
what is the process of events to create bone? (5) (CCCBO)
1) Chondrocytes hypertrophy
2) Cartilage matrix calcifies
3) chondrocytes die
4) blood vessels grow into lacunae
5) Osteoblasts deposit bone
what does the epiphyseal plate consist of?
zones resting cartilage (nearest the epiphysis), proliferation, hypertrophy and calcification.
what does messenchymal cells do during intramembranous ossification? (3) (BSF)
1) become osteoblasts in an ossification center
2) secrete bone matrix
3) form trabeculae of woven bone
what does messenchyme form during endochonral ossification?
a hylaine cartilage model of the bone
what is an example of an irregular bone?
sphenoid bone from the skull or scapula
what initially accelerates bone growth?
reproductive hormones
in the zone of hypertrophy during long bone growth what is happening?
chondrcytes enlarge
how do reproductive hormone accelerate bone growth?
eventually the zone of calcification catches the zone of proliferation and the epiphyseal plate closes
what is red marrow and where is it located?
connective tissue in the spaces of spongy bone or medullary cavity (in diaphysis)
what do blood vessels, osteoblasts and osteoclasts penetrate the epiphysis to form?
secondary ossification centers
what is the diaphysis composed of?
primarily compact bone but it can also contain spongy bone