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Pathophysiology > module 9 bone formation > Flashcards

module 9 bone formation Flashcards

1
Q

axial skeleton

A

80 bones
skull
vertebral column
thorax

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2
Q

appendicular skeleton

A

126 bones
upper and lower extremities
shoulder girdle
pelvic girdle

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3
Q

bone cells

A

osteoblast
osteocyst
osteoclast

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4
Q

osteoblast

A 
derived form mesenchymal cells
produce type 1 collagen
responde to parathyroid hormone
produce osteocalcin
synthesize osteoid (nonminderalized bone matrix)
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5
Q

osteocyte

A

transformed osteoblast surrounded in osteoid as it hardens from deposited minerals

  • maintain bone
  • help regulate Ca and Phos.
  • stimulated by calcitonin
  • inhibited by PTH
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6
Q

osteoclast

A

from hematopoetic tissue (monocyte/macrophage lineage)
major reabsorptive cell of the bone
large, multinucleated cells
contain lysosomes filled with hydrolytic enzymes

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7
Q

bone maxtrix

A 
organic part: 25%
- collagen
- proteoglycans
- glycoprotines
inorganic part: 65%
- calcium
- phosphate
-- crystals of these minerals called hydroxyapatite
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8
Q

osteoid

A

organic matrix

- collagen fibers extend along parallel lines of tension: give bone tinsel strength and some flexibility.

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9
Q

proteoglycan

A

part of osteoid
polysaccaride that binds between collagen fibers and surrounds cells.
may transfer mechanical info within matrix

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10
Q

Inorganic matrix

A

mineral content bound and embedded in in matrix gives bone hard, rigid structural strength reservoir for the body calcium and phosphorus

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11
Q

basic unit of bone

A

osteon or the harersian system

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12
Q

haversian canal

A

blood vessels and nerve fibers run through this

-surrounded by mineralized matrix: lamellae

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13
Q

lucunae

A

small cavities bordering the lamellae that contain a bone cell, osteocyte.

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14
Q

canaliculi

A

small channels that connect adjacent lamellae, allows nutrients to move through

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15
Q

2 bone types

A

cancellous/trabecular/spongy

compact/cortical

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16
Q

cancellous/spongy bone

A

network of thin plates and rods: trabeculae

  • found within ends of long bones, vertebral bodies, flat bones (pelvis)
  • trabeculae laid in response to stress and shaped to accommodate loads placed on bone
  • enclosed in shell of compact bone
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17
Q

compact/cortical bone

A

resistant to compression
dense in structure
laid in concentric layers

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18
Q

periosteum

A

tough fibrous memrane that covers all bone

  • highly vascularized
  • provides nutrition via volkmann canals
  • inner layer contains osteoblasts
  • covers entire bone except for the ends which are covered by hyaline (articular) cartilage
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19
Q

long bones

A

medullary cavity: central cavity is present

  • endosteum: thin membrane that lines inside of cavitiy
  • – contains osteogenic cells
  • in children: filled with red marrow
  • in adults: largely yellow marrow
  • – red marrow primarily in flat bones of adults
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20
Q

endochondral ossification

A

longitudinal bone growth, evident in embryonic development, fracture healing, some bone tumor growth.

  • mesenchymal cells differentiate into chondrocytes which produce a carilaginous “model” of bone
  • mineralized starting at center (primary assification)
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21
Q

endochondral secondary ossification

A

centers form near ends of long bones ( epiphyses)

- future site of bone growth into teen years.

22
Q

intramembranous ossification

A

flat bones grow by circumferential growth process

- vascularized fibrous tissue becomes mineralized as the mesenchymal cells present differentiate into osteoblasts.

23
Q

continuous bone growth

A

bones increase in length only through growth within cartilage plate followed by endochondral ossification

24
Q

epiphyseal plate

A

allows for lengthening of diaphysis and metaphysis
- site of continuous growth
growth and thickening of cartilage cells of the plate move the epiphysis away from the metaphysis
- calcification and replacement of cartilage occur on metaphyseal surface

25
Q

metaphysis

A

between diaphysis and epiphysis

26
Q

zones of epiphyseal plate

A

calcifying cartilage
maturing cartilage
proliferating cartilage
resting cartilage

27
Q

calcifying cartilage zone

A

thin line of condrocytes
weakest part of plate
condrocytes no longer active due to calification of matrix

28
Q

resting cartilage zone

A

maintain adherence of plate to epiphysis

29
Q

proliferating cartilage zone

A

young

demonstrates most active cell growth

30
Q

maturing cartilage zone

A

contains enlarged and mature cartilage cells as they migrate towards the metaphysis

31
Q

osteoblast within periosteium

A

responsible for growth in width of bones via intramembranous ossification

32
Q

thyroxine hormone

A

decreased levels lead to dwarfism

33
Q

GH

A

decreased levels lead to dwarfism

increased levels lead to giantism

34
Q

estradiol hormone

A

during puberty causes more rapid maturation and fusion of plates
- can limit growth spurts of puberty, and early sexual maturity, especially in girls, leading to shorter stature

35
Q

bone remodeling phases

A

1: activation phase
2: resorption phase
3: formation phase

36
Q

activation phase of remodeling

A

osteoclasts are responsible for bone breakdown

  • has receptor for RANK L that stimulate bone reabsorption
  • stimulated by IL-10 and bisphosphonates
37
Q

reabsorption phase of remodeling

A

osteoclasts form a cutting cone, resorb bone, and leave behind and elongated cavity

  • compact bone: resorption cavity follows longitudinal axis
  • spongy bone: resorption cavity parallels the surface of the trabeculae
38
Q

formation phase of remodeling

A

new bone laid down by osteoblasts lining the walls of the resorption cavity

  • successive layers laid down
  • new trabeculae formed in spongy bone
39
Q

RANKL

A

secreted by osteoblast
receptor on osteoclast
- when activated cutting and resorbing of bone continues

40
Q

OPG

A

secreted by osteoblast
receptor antagonist for RANK receptor
deactivates osteoclast

41
Q

RANKL expression

A 
increased by
- IL: 1, 11, 17
- PTH
- prostaglandin 
- glucocorticoids
decreased by 
- IL-4
- estradiol
42
Q

OPG production

A 
increased by 
- IL: 1, 13, 18
- estradiol 
- leptin
- mechanical strain
Decreased by 
- PTH 
- prostaglandin
- glucocorticoids
- cyclosporin
43
Q

calcium homeostasis

A
  • majority of Ca stored in bone
  • blood concentration tightly controlled
  • PTH maintains serum Ca levels by increasing bone reabsorption as well as Ca reabsorption in renal tubules
  • Vit. D increases bone mineralization by increasing Ca absorption in GI tract
    • in Ca defeciency can stimulate bone resorption to maintain blood concentration
44
Q

calcitonin

A

inhibitor to bone resorption

45
Q

5 stages of fracture healing

A 
hematoma formation
fibrocartilage formation
callus formation
ossification
consolidation/remodeling
46
Q

hematoma formation, fx healing

A

size depends on amount of damage
offers some stability to fractured ends
inflammation

47
Q

fibrocartilage formation, fx healing

A

3 days- 2 weeks

granular tissue containing blood vessels, fibroblasts, osteoblasts

48
Q

callus formation, fx healing

A

2-6 weeks
cartilaginous callus
formation of bone at periosteal surfaces to unite outer ends
if this stage is delayed or interrupted final stages do not occur

49
Q

Ossification, fx healing

A

3-6 months
space in bone bridged and fractured ends united
callus slowly replaced by spongy bone

50
Q

consolidation/remodeling, fx healing

A

6 weeks - 1 year
medullary canal established
bone resorbed and deposited along stress lines to meet mechanical requirements

Pathophysiology (80 decks)

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