Bone II

Question 1

what does the endosteum line? what does it contain?

Answer 1

marrow cavity
volkmann’s canal
haversian canal

contains osteogenic cells

Question 2

what are the two was bone develops?

Answer 2

intramembranous bone formation

endochondrial bone formation

Question 3

what is intramembraneous bone formation?

Answer 3

development within layer of condensed mesechyme

Question 4

what is endochondrial bone formation?

Answer 4

occurs via a cartilage model that is replaced by bone

Question 5

what kind of bone is always formed first? followed by what?

Answer 5

primary

secondary - slower remodeling

Question 6

how does intramembraneous bone formation begin?

Answer 6

when mesechymal cells condense to form a primary ossification center — osteoblasts differentiate and begin secreting osteoid

Question 7

what happens when osteoblasts become trapped in their own matrix (osteoid)?

Answer 7

they become osteocytes

Question 8

what is the name given to bone that is formed in the priamry ossification center of IBF?

Answer 8

bone trabecular (fused spicules)

Question 9

as the trabeculae join together what forms?

Answer 9

spongy bone

Question 10

what happens at the same time blood vessels invade the area?

Answer 10

undifferentiaed mesechymal cells give rise to bone marrow cells

Question 11

what fuses together to form bone?

Answer 11

ossification centers

Question 12

what kinds of bone are formed by intramembraneous bone formation?

Answer 12

flat bones of the skill

Question 13

what are the five hstiologically distinctive zones starting from the epiphyseal side of the plate?

Answer 13

zone of reserve cartilage
zone of cell proliferation
zone of cell maturation and hypertrophy
zone of calcifying cartilage
zone of provisional ossification

Question 14

what is the zone of reserve cartilage?

Answer 14

cartilage with small randomly arranged inactive chondrocytes

Question 15

what is zone of proliferation>

Answer 15

rapid mitotic division give rise to rows of cartilage cells

Question 16

what is the zone of cell matruation and hypertrophy?

Answer 16

chrondrocytes are greatly enlarged and contain glycogen and the cartilage maxtric between neighboring cells becomes thin

Question 17

what is the zone of calcifying cartilage?

Answer 17

lacunae confluent and the remnants of interlacunar matrices become calcified, causing chondrocytic death

Question 18

what is the zone of provisional ossification?

Answer 18

bone is beginning to be elaborated upon the calcified cartilage, and osteolytic activaty begins to resorb the calcified bone calfiedi cartilage complex

Question 19

what two things do not undergo ossification and why?

Answer 19

periosteium and endosteum

develop from portions of the mesechymal layer that do not under ossification

Question 20

how are long bones formed?

Answer 20

endochondrial bone formation

Question 21

how does endochondrial bone formation begin?

Answer 21

a segment of hyaline cartilage serves as a model for bone

Question 22

what are the two stages of endochondrial bone formation?

Answer 22

development of
primary ossification center
seconadary ossification center

Question 23

where does the primary ossification center develop?

Answer 23

midriff of the diaphysis

Question 24

what is teh periosteum?

Answer 24

vascularization of the perichondrium = osteoprogenitor cells –> osteoblasts

Question 25

how is the subperiosteal bone collar formed?

Answer 25

osteoblasts secrete matrix deep to perichondrium via intramembraneous bone formation

Question 26

what happens to the chondrocytes qwithin the core of the cartilaginous model?

Answer 26

undergo hypertrophy and degen. = forming marrow space

Question 27

what is in the periosteal bud?

Answer 27

blood vessels osteoprogenitor cells mesenchymal cells

Question 28

where do secondary ossification centers develop?

Answer 28

epihysis

Question 29

what occupys howships lacunae?

Answer 29

osteoclasts - multinucleated

Question 30

what are monocyte precursors?

Answer 30

osteoclasts

Question 31

the inner layer of teh periosteum possesses what?

Answer 31

osteoprogenitor cells

Question 32

what is teh outer periosteum?

Answer 32

fibrous

Question 33

what is the function of the periosteum?

Answer 33

to distribute blood vessels to bone - apposition growth!

Question 34

how do osteocytes communicate with eachother?

Answer 34

through gap junctions on proceses that extend through canaliculi

Question 35

what will a diet deificny in calcium lad to?

Answer 35

fragile bones

Question 36

what does excessive growth hormone cause?

Answer 36

acromegaly

Question 37

what does excessive vitamin D cause?

Answer 37

bone resorption

Question 38

what will an excess or deficinecy in vit A leads to (extremes)?

Answer 38

short stature - epiphyseal plates closing early

Question 39

what does hypervitaminosis A do?

Answer 39

accelerate ossification of epithyseal plates

Question 40

what does hypovitaminosis A do?

Answer 40

reduce the width of the epiphyseal plates

Question 41

what happens in the absence of vitamin D?

Answer 41

epiphyseal chondrocytes continue to proliferate but matrix does not calcify -- increase osteoid - unmineralized = rickets

Question 42

what are the primary manufacturerrs of collagen in long bones?

Answer 42

osteoblasts