Forming a skeleton Flashcards
describe origin of skeletal cells
common mesenchymal progenitor gather and condense then differentiate into chondrocytes and osteoblasts
Neural crest cells give rise to___, sclerotome of somites ___, lateral plate ___
craniofacial bone, axial, appendicular
two types of bone development
intramembranous-craniofacial bones, direct condensation of mesenchyme. endochondral-cartilage intermediate
three types of lamellae in compact or cortical bone
concentric, interstitial, circumferential
constituents of bone in decreasing proportion
mineral, collagen, water, noncollagenous proteins, lipids
major fiber of the bone matrix
type 1 collagen with triple-helical structure. Also some type 5 collagen
lineage of osteoclasts and cytokines necessary for differentiation
monocytes; RANKL and M-CSF (CSF-1)
origin of osteocytes, chondrocytes osteoblasts
osteo-chondrogenic mesenchymal cell> osteoblast or chondrocyte. Osteoblast> osteocyte
How you livin osteocyte?
in a lacunae with dendrites going thru canaliculi
describe bone modeling and remodeling processes
modeling-two surface process controlled by PTH, remodeling- one surface
what endocrine fxns does the skeleton have
calcium, phosphate, glucose, testosterone
two cytokines which demonstrate cyclic periodicity in bone development
Notch and Wnt
difference between lysines of cartilage and bone
only partially hydroxylated in bone
blood vessels and nerves are found w/in___
haversian or central canal and connected by volkman’s canal
what cells are responsible for regulating ossification?
osteoblasts via apatite deposition on collagen
how does an osteoclast break down bone
makes a sealing zone, secretes acid hydroases which break down apatite and eventually collagen
how does calcium acquisition differ from fetus to newborn
fetal liver produces PTH then mom’s ca crosses placenta. Newborn intestinal absorption controlled by calcitriol
actions of PTH
increases renal Ca retention, conversion of calcitriol, bone resorption
what determines phosphate balance? what is it in kids? adults?
kidney. positive in child, even in adults
FGF-23: driven by? effects? interacts with? Expressed by?
high phosphate. increases phosphaturia, less calcitriol. Klotho receptor. Osteocytes.
interaction of FGF23, PTH, 1,25OHD
all have neg feedback loops. PTH stimulates both, is inhibited by boht. FGF23 inhibits both and is stimulated by both. 1,25 has opposite effect on PTH and FGF23
how do bone cells talk?
RANKL secreted by osteoblasts bind to RANK on clasts. OPG inhibits RANK. Formation and resorption
how does bone regulate testosterone
osteocalcin
