Structure & Function - Bone

hatitero's version from 2017-09-21 12:55


Question Answer
2 types of bone makeup’s cortical and cancellous
material that covers the outer surface of the bone periosteum
lining of the internal surface of the bone endosteum
2 components that make up bone structureinorganic components and organic components
properties of inorganic components of bone 70% of bone mass, gives hardness, made of calcium phosphate in the form of hydroxyapatite
properties of the organic component of bone 30% of bone mass, gives elasticity and resillence, consists of collagen 1 fibers, GAGs. some non-collagen organic material
how to make bone flexible dissolve away CaPO with acid

endochondral bone phases

Question Answer
restingchondrocytes doing nothing
proliferatingchondrocytes in columns
maturation/hypertrophybigger chondrocytes in columns
calcificationchondrocytes begin to calcify the matrix, cutting of their own circulation and dying
ossificationosteoblasts come into the lacunae left by chondrocytes and lay down bone on cartilage matrix

Ossification centers

Question Answer
metatarsals, phalangessecondary center in one epiphysis
femurmultiple ossification centers in one epiphysis
tibiasecondary ossification center in tuberosities
short bonesone primary ossification center
long bonesone primary center, two secondary centers
calcaneusone primary and one secondary center
os coxae3 primary 5 secondary centers


Question Answer
what makes up the synovial capsulethe periosteum being continuous between the two bones of the joint
describe intramembranous bone formation bone develops directly from mesenchyme… mesynchymal cells condense and vascularize, they differentiate into osteoprogenitor cells, they secrete osteoid then mineralize the matrix into immature bone. this immature bone is remodeled into lamellar bone by osteoclasts and osteoblasts
what is eventually bccoming the periosteumthe surrounding mesenchymal tissue
type of ossification that occurs in flat bone intramembranous bone formation
endochondrial bone formation involves replacement of hyaline model by bone
types of growth in endochondrial bone formation grows by interstitial and appositional growth
bone formation in long, short and irregular bones endochondrial bone formtation
embryonic derivation of blood vessels mesoderm
pathway of endochondrial bone formation formation of hyaline cartilage… ossification begins with bony collar for support… chondrocytes between the bony collar hypertrophy and die… periosteal sprout brings in osteoprogenitor cells… osteoblasts form and lay down osteoid… osteoid gets calcified
secondary ossification centers location sites epiphyses of long bones, some only have 1, some have multiple, some 2ndary also occur in tuberosities
side of epiphysial plate with more bone formation epihyseal end has more formation than the diaphyseal end
5 zones of epyphiseal plate resting, proliferating, maturation, calcification, ossification
describe the 5 zones resting: inactive chondrocytes… proliferating: chondrocytes align, undergo mitosis… maturation: chondrocytes in columns but much larger… Calcification: chondrocytes calify the matrix and die, leaving spaces for osteoblasts… Ossification: osteoblasts lay down bone on the cartilidge matrix, osteoclasts reform the marrow cavity
area responsible for growth in length of long bone epiphyseal plate
mechanism for growth ion diameter appositional growth of periosteum
Bone remodling does what breaks down spongy bone and reforms compact bone
how many ossification centers of short bone 1
how many ossification centers of calcaneus 2
ossification centers in os coxae3 primary 5 secondary
ossification centers of irregular bones single or multiple primary and secondary oss centers
steps of the fracture repair hemmorage in area forming physiological splint… formation of procallus (clotting and granulation tissue), callus formation from periosteum (formation of new chondroblasts from osteoprogenitor), bony callus formation (osteoprogenitors to osteoblasts that replace cart with spongy bone… spongy bone replaced with compact bone
most useful form of Calcium in bodyin the blood, as unbound calcium ions
main use for bound calciumstructural stability
what happens to CaPO4 sdaltsthis is the form they take when precipitated out of solution. They are deposited into bone, occasionally can get precipitate elsewhere which causes problems
ECF concentration needed for CaPO precipitationneeds to be supersaturated
2 forms of precipitated CaPO4loose in the ECF or in crystalsd
where is the largest store reserve for CaPO4in bones
which is worse hypercalcemia or hypocalcemiahypocalcemia, this causes hypersensitivity of the nerves resulting in the possibility for muscle spasms. if this happens in an area like the trachea you could not be able to breath
structural makeup of bone70% mineral and 30% osteoid
role of ions in calcium bone crystalsadd strength to the bone
describe bone fluidthe same as ECF but it is contained within the haversian system sealing off a local environment
way osteocytes communicate with osteoblaststhey have gap junctions in the canaliculi
Ca movement via canaliculiCa and other materials can be exchanged with the extra-osseous environment via exchange thru canaliculi. Osteocytes can grab Ca from bone and ship it to the ECF via gap junctions with osteoblasts
secretions of osteoblastscollagen, proteoglycans, and alkaline phosphotase
role of alkaline phosphotaseit clease a double phosphate molecule making 2 phosphates… this process raises the PO¬4 concentration possibly resulting in precipitation of CaPO crystals
“band leader” of bone remodelingthe osteocytes are able to signal all the processes needed to remodel bone
2 methods osteoclasts break down bonesecrete enzymes that break down the osteoid, and pump out acids to dissolve away the calcium
what prevents the initial PO4 from binding Ca and coming out of solution in bonepyrophosphotate, the double phosphate molecuyle
where does the proton bind in the acidic resporption environmentto the phosphate making HPO4
which bone cell type detects nessecary bone remodelingthe osteocytes which can then signal all the other molecules
how do osteoblast activate osteoclaststhey have the RANK ligand (RANKL) and when free, the osteoclasts can bind to that and become activated by going on to maturity
how do osteoblasts inhibit osteoclaststhey produce osteoprotegrin, which binds to the RANKL and inhibits the maturation of the osteoclasts
method of internal bone remodelingthe osteoclasts work from in to out, stopping at the concrete layer, then the osteoblasts build bone back from out to in
what is the concept of wolf’s lawbone is remodeled to meet mechanical demands
what are the mechanical sensors of bonethe osteocytes, they have cilia that detect prossure and flow changes in the bone fluid
describe the piezoelectric effectpressure creates a negative electrical gradient on the compressed side of bone, and a positive charge on the stretched side of bone
what chemical prevents precipitation of CaPO4 in plasmapyrophosphate