Forming a skeleton

Question 1

describe origin of skeletal cells

Answer 1

common mesenchymal progenitor gather and condense then differentiate into chondrocytes and osteoblasts

Question 2

Neural crest cells give rise to___, sclerotome of somites ___, lateral plate ___

Answer 2

craniofacial bone, axial, appendicular

Question 3

two types of bone development

Answer 3

intramembranous-craniofacial bones, direct condensation of mesenchyme. endochondral-cartilage intermediate

Question 4

three types of lamellae in compact or cortical bone

Answer 4

concentric, interstitial, circumferential

Question 5

constituents of bone in decreasing proportion

Answer 5

mineral, collagen, water, noncollagenous proteins, lipids

Question 6

major fiber of the bone matrix

Answer 6

type 1 collagen with triple-helical structure. Also some type 5 collagen

Question 7

lineage of osteoclasts and cytokines necessary for differentiation

Answer 7

monocytes; RANKL and M-CSF (CSF-1)

Question 8

origin of osteocytes, chondrocytes osteoblasts

Answer 8

osteo-chondrogenic mesenchymal cell> osteoblast or chondrocyte. Osteoblast> osteocyte

Question 9

How you livin osteocyte?

Answer 9

in a lacunae with dendrites going thru canaliculi

Question 10

describe bone modeling and remodeling processes

Answer 10

modeling-two surface process controlled by PTH, remodeling- one surface

Question 11

what endocrine fxns does the skeleton have

Answer 11

calcium, phosphate, glucose, testosterone

Question 12

two cytokines which demonstrate cyclic periodicity in bone development

Answer 12

Notch and Wnt

Question 13

difference between lysines of cartilage and bone

Answer 13

only partially hydroxylated in bone

Question 14

blood vessels and nerves are found w/in___

Answer 14

haversian or central canal and connected by volkman’s canal

Question 15

what cells are responsible for regulating ossification?

Answer 15

osteoblasts via apatite deposition on collagen

Question 16

how does an osteoclast break down bone

Answer 16

makes a sealing zone, secretes acid hydroases which break down apatite and eventually collagen

Question 17

how does calcium acquisition differ from fetus to newborn

Answer 17

fetal liver produces PTH then mom’s ca crosses placenta. Newborn intestinal absorption controlled by calcitriol

Question 18

actions of PTH

Answer 18

increases renal Ca retention, conversion of calcitriol, bone resorption

Question 19

what determines phosphate balance? what is it in kids? adults?

Answer 19

kidney. positive in child, even in adults

Question 20

FGF-23: driven by? effects? interacts with? Expressed by?

Answer 20

high phosphate. increases phosphaturia, less calcitriol. Klotho receptor. Osteocytes.

Question 21

interaction of FGF23, PTH, 1,25OHD

Answer 21

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

Question 22

how do bone cells talk?

Answer 22

RANKL secreted by osteoblasts bind to RANK on clasts. OPG inhibits RANK. Formation and resorption

Question 23

how does bone regulate testosterone

Answer 23

osteocalcin