Bone Part 2 Flashcards

1
Q

Size of the Haversian System

A

= size of osteoclast
(200um in diameter)

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2
Q

Bone Remodeling

A

produces osteons

-removal of existing bone by osteoclast
-redeposition of new bone by osteoblast

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3
Q

The outer margin of the osteon is

A

“cement line”

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4
Q

Is bone remodeling continuous?

A

yes (bone is an active organ)

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5
Q

What are the 3 phases of the bone remodeling cycle?

A
  1. resorption
  2. reversal
  3. formation
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6
Q

resorption

A

osteoclast digest old bone

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7
Q

reversal

A

mononuclear cells appear on bone surface

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8
Q

formation

A

osteoblast lay down new bone (until it is replaced completely)

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9
Q

Bone remodeling is both

A

systemic (Ca) and local

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10
Q

The major systemic regulator of bone remodeling are

A

-PTH
-Calcitonin
-Growth Hormones
-Glucocorticoids
-Sex Hormones

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11
Q

Wolf’s Law

A

apply a force to a bone will respond to that force
(braces)

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12
Q

Pattern of bone remodeling is determined by

A

local mechanical stresses (force)

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13
Q

Endochondral ossification

A

-replacement of cartilage precursor with bone
-most of the body

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14
Q

Where would you find Endochondral ossification

A

long bones, vertebrae, pelvis, and base of the skull

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15
Q

Intramembranous ossification

A

-direct replacement of mesenchyme bone

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16
Q

Primary Ossification Center

A

mid-diaphysis

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17
Q

Secondary Ossification Center

A

epiphyses

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18
Q

Process of Endochondral ossification

A
  1. primitive mesenchyme cells differentiate into chondroblast, lay down early perichondrium
  2. cartilage model made
    3.osteoprogenitor cells and osteoblast lay down bone, Bone Collar
    4.Starts to Calcify (chondrocytes die due to lack of blood)
  3. Blood vessel are brought in along with osteoprogenitor cells and osteoblasts
  4. Replace everything in diaphysis (1’)
  5. secondary ossification sites occur (after birth)
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19
Q

Bone Collar or Periosteal Cuff

A

first bone laid down and is under perichondrium on the shaft

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20
Q

Epiphseal Plate

A

-region of the metaphysis left open (unmineralized)
-allow conintous longitudinal growth

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21
Q

What is still visible on x-ray after a epiphyseal plate has closed?

A

epiphyseal line

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22
Q

In humans, what is the last long bone epiphyseal plate to close?

A

femur (age 18-20)

23
Q

What cause epiphyseal plate to close?

A

hormonal changes (decrease cartilage proliferation)

24
Q

Zones of the epiphyseal plate (starting at 2’ ossification center)

A

1.resting zone
2. proliferative zone
3.hypertrophic zone
4. calcification zone
5.ossification zone

25
Q

Resting Zone/ Reserve Cartilage

A

-hyaline cartilage
-no cell division

26
Q

proliferative zone

A

-rows/columns of chondrocytes
-adds length
-cartilage cells undergo mitosis

27
Q

hypertrophic zone

A

-big mature chondrocytes
-large amounts of glycogen

28
Q

Calcification Zone

A

-matrix becomes calcified
-cartilage cells die

29
Q

ossification zone

A

-area where blood vessels comes in along with osteoprogenitor cells, osteoblasts, and osteoclasts
-new bone is forming

30
Q

Process of Intramembranous Ossification

A
  1. mesenchymal cells differentiate directly into osteoblast
  2. Synthesize osteoid in multiple spots (multiple centers)
  3. Mineralization occurs
    4.
    5.Osteoblasts get trapped and become osteocyte
  4. Trabecular bone and periosteum form
  5. Cortical bone forms
  6. Red blood vessels form red marrow
    8.
31
Q

Spicule of Bone

A

irregular island of bone growth (Intramembranous Ossification)

32
Q

Simple Bone Fracture

A

no break in the skin

33
Q

3 most common bone fractures

A

simple
compound
comminuted

34
Q

compound fracture

A

damage to skin exposing the bone

35
Q

comminuted fracture

A

bone broken into many pieces (shatter)

36
Q

Bone Repair Stages

A
  1. Hematoma Formation
  2. granulation tissue callus forms
  3. bony callus forms
  4. bone remodeling
37
Q

Hematoma

A

forms when blood rushed into the fracture site

38
Q

What do you find at the site of fracture in the acute phase

A

-neutrophils
-macrophages

38
Q

About a week after the fracture you see

A

-fibroblast
-cappilaries proliferate and grow into new site

39
Q

granulation tissue

A

-vascular collagenous tissue
-get more and more fibrous (acute to chronic)

40
Q

granulation tissue is replaced by

A

hyaline cartilage (provisional callous)

41
Q

bony callus formation

A

1.osteoprogenitor cells and osteoblasts form endosperm and periosteum at edge of the wound and grow inward
2. mesh work of woven bone within the provisional callous
3. deposit calcium salt in collagen matrix
4. becomes bony callous (want to have bone “set” before this forms)

42
Q

When the fracture site is completly bridged by woven bone this is known as

A

bony union

43
Q

How long does the process of bone remodeling take after a fracture?

A

6-12 weeks (depending on size and location)

44
Q

Synovial Joints are also know as

A

diarthroses

44
Q

Synovial Joints

A

-extensive movement
-joint capsule

45
Q

Synovium

A

-membrane that lines joint cavity
-secretes synovial fluid
- no basement membrane
-4 cell layers

46
Q

What are the two types of cells in found in Synovium

A

type A
type b

47
Q

Type A - Synovicyte

A

-like macrophage
-non-fixed (can move)
-remove cell debris
-present antigens

48
Q

Type B- Synovicyte

A

-resemble fibroblast
-make fluid
-make lubricin
- proper Synovicyte

49
Q

Type A Synovicyte are derived form

A

blood-borne mononuclear cells

50
Q

Type B Synovicyte produce

A

-hyaluronan
-collagens
-fibronectin
-lubricin

51
Q

Lubricin

A

-surface active mucinous glycoprotein
-important role in cartilage integrity
-prevents protein and cell adhesion