Bone

Question 1

bone

definition

Answer 1

specialized CT (mineralized, rigid)
living tissue (cells, vessels, nerve fibers)
continuously remodeled
storage for minerals (calcium)
regulates blood calcium levels (via hormones)
supports/protects organs
leverage for movement

Question 2

remodeling

general

Answer 2

pressure applied
bone reabsorption/breakdown
tension on bone
bone deposition (addition)

orthodontics, treat adults and kids

Question 3

long bone structure

Answer 3

epiphysis head w/ spongy bone

diaphysis shaft w/ compact bone around marrow/medullary cavity

epiphysis head

surrounded by periosteum except articular surface

Question 4

membranes of bones

Answer 4

periosteum - around bone
endosteum- inside bone

Question 5

periosteum

Answer 5

external CT capsule covers outer surface except
articular surfaces and tendon insertions

Question 6

active periosteum

Answer 6

layers:
outer fibrous = collagen
inner cellular = immature bone cells aka osteoprogenitor and osteoblasts

Question 7

inactive periosteum

mature

Answer 7

outer fibrous = dense irregular collagen CT, blood and lymph vessels, nerves
-anchored by Sharpe’s fibers to prevent sliding

inner cellular= periosteal cells > osteoblasts if needed for repair
-one layer thick

Question 8

endosteum

Answer 8

internal CT capsule w/ osteoprogenitor cells and osteoblasts
lines bone marrow cavity, spongy bone
contain haversian and volkman canals for small vessels and nerves to reach bone

Question 9

inorganic component bone matrix

Answer 9

minerals
hydroxyapatite crystals (calcium phosphate)
bicarbonate, citrate, Mg, Na, K

gives bones hardness

Question 10

organic component bone matrix

Answer 10

proteins
fibers (collagen I)
ground substance (proteoglycans, glycoproteins, growth factors/BMPs)

Question 11

cells of bone tissue

Answer 11

mesenchymal stem cells
osteoprogenitor cells
osteoblasts
osteocytes

Question 12

osteoclasts

Answer 12

from mononuclear hemopoietic progenitor cells

break down/ resorb/ remodel/scuplt bone, miners of minerals from matrix

multinucleated, motile, acidophilic

@ howship lacuna-depression on bone

Question 13

osteoprogenitor cells

Answer 13

early stage immature bone cells
@ deep layer periosteum and endosteum

Question 14

osteoblasts

Answer 14

cuboidal shape
synthesize osteoid (organic matrix, pre-bone)
non-mineralized

Question 15

bone lining cells

Answer 15

flat and quiescent
covere surface to protect from osteoclasts

Question 16

osteocytes

Answer 16

‘grown up’ osteoblasts
maintain matrix
enclosed in lacuna surrounded by bone then surrounded by osteoid halo

Question 17

chronic renal failure

CRF

Answer 17

inadequate levels of calcium and phosphate ions so osteoid not mineralized

Question 18

haversian system

Answer 18

osteocytes enclosed in lacuna w/ cytoplasmic processes branching off in canaliculi oriented toward canal

concentric rings around canal

ECM provides nutrients/oxygen/hormones

small artery, vein, nerves, NO lymphatics

Question 19

osteoclast regions

Answer 19

ruffled border= resorption, breakdown
clear zone= adhesion, seals around bone w/ actin ring
vesicular= exo/endocytosed material
basal = organelles, nuclei

Question 20

ruffled border

Answer 20

cell membrane infoldings
exocytosis hydrolytic enzymes
secrete protons into reabsorption compartment to dissolve inorganic matrix
endocytosis of broken bone

Question 21

clear zone

Answer 21

no organelles
action microfilaments
sealing zone to isolate resorption compartment

Question 22

vesicular zone

Answer 22

exocytotic vesicles w/ lysosomal enzymes
endocytic vesicles w/ bone breakdown products

Question 23

basal zone

Answer 23

organelles and multiple nuclei
exocytosis of broken down matrix

Question 24

organic breakdown

Answer 24

1. lysosomal enzymes released by osteoclasts into resorption compartment
2. products of breakdown pass into osteoclast for degradation into amino acids/monosaccharides/disaccharides pass into capillaries
3. osteoclasts apoptose

Question 25

gross structure | description

Answer 25

compact-dense, solid cancellous- spongy, porous

Question 26

dense bone

Answer 26

haversian systems/osteons w/ concentric lamellae of bone | haversian system is functional unit of compact bone

Question 27

cancellous bone

Answer 27

irregular bone lamellae not osteons

Question 28

skull cap development

Answer 28

outer table= compact, covered by periosteum (pericranium) center = spongy bone w/ marrow (diploe) inner table = compact, periosteal layer of cranial dura mater

Question 29

primary bone | type

Answer 29

immature, woven, random orient collagen during fetal development and bone repair temporary and resorbed by osteoclasts replaced by secondary | lining tooth sockets remains immature thru life

Question 30

secondary bone | type

Answer 30

parallel or concentric bone lamellae collagen fibers parallel w/i lamellae more mineral content than primary stronger than primary spongy or compact

Question 31

lamellar systems | compact bone

Answer 31

outer circumferential lamellae= deep to periosteum interstitial lamellae= fragments, remnants of old osteons, interspersed w/i haversian inner circumferential = around bone marrow cavity

Question 32

rickets

Answer 32

from calcium deficiency or inadequaate dietary supply of vitamin D for calcium absorption osteiod not mineralize properly so soft bones

Question 33

osteoporosis

Answer 33

reduction in bone mass = porous breakdown > formation lose horizontal trabeculae, thicker vertical shorter vert. bodies from compression fractures | postmenopausal women estrogen dec, interleukin 1 & tumor necrosis inc

Question 34

bone tissue development | environment

Answer 34

1. in mesenchyme membrane 2.hyaline cartilage

Question 35

mechanisms of development

Answer 35

intramembranous (mesenchyme) endochondral (hyaline)

Question 36

development steps

Answer 36

1. intramembranous OR endochondral 2. osteoblasts form primary immature 3. resobed my osteoclasts 4. replaced by secondary mature SPONGY 5. spongy stays spongy or becomes compact

Question 37

intramembranous

Answer 37

bone directly within membrane of highly vascularized mesenchyme flat bones | skull is flat bone

Question 38

endochondral formation

Answer 38

in hyaline cartilage model long bones

Question 39

endochondral formation | steps

Answer 39

1. hyaline cartilage model with perichondrium 2. cartilage grows interstitially and appositionally 3. perichondrium vascularized 4. signal inner layer to differentiate into osteoblasts 5. perichondrium > periosteum 6. bone collar form via intramembranous to block diffusion of nutrients 7. chondrocytes die 8. osteoclasts perforate collar 9. periosteal bud enters w nutrients and cells 10. osteoprogenitor cells > blasts > osteoid on remnants of calcified cartilage 11. hemopoietic form bone marrow | all primary center , diaphysis, before birth

Question 40

endochondral formation | secondary center

Answer 40

epiphyses, after birth same process as primary w/o bone collar cartilage stays in articular surfaces and growth plates (until 18-20)

Question 41

length growth

Answer 41

via endochondral in growth plates thickness of plates stays same but distance b/t inc

Question 42

zone of epiphyseal growth plates

Answer 42

1.reserve cartilage= typical hyaline 2.proliferation= interstitial growth by isogenous groups mitosis, cells inc # 3.maturation 4.hypertrophy 'popcorn' glycogen, vacuoles 5.calcification/degeneration 6.ossification= calcified cartilage remnants + newly formed bone + osteoblasts + osteocyte + bone marrow

Question 43

growth plate additions

Answer 43

bone added to diaphyseal side so pushes epiphysis away

Question 44

growth in width

Answer 44

bone deposition via appositional added to outer surface bone resorption via osteoclasts inside

Question 45

mineralization of matrix

Answer 45

hydroxyapatite crystals take over vesicles from mineral growth | osteocalcin and sialoproteins

Question 46

bone repair | steps

Answer 46

1. trauma 2. neutrophils and macrophages clean debris 3. Bv's and fibroblasts grow into blood clot 4. granulation tissue forms (LCT) 5. DCT and fibrocartilage form 6. periosteal osteoprogenitor cells > blasts> osteoid 7. bone shell on fibrocartilaginous callus 8. osteogenic buds callus 9. cartilage calcify > die > replaced 10. bony callus replaces fibro callus 11. spongy bone forms 12. replaced by compact 13. remodeled

Question 47

achondroplasia | clinical correlate

Answer 47

genetic disorder of bone growth= dwarfism cartilage of epiphyseal plates (proliferation and hypertrophy small)

Question 48

fibrodysplasia ossificans progressiva | clinical correlate

Answer 48

rare CT disease from autosomal dominant mutation in repair mechanisms soft tissues damaged > repaired w/ bone = loss mobility, difficulty breathing, prison may be spontaneous