Exam 2 - MSK 1A Bone: Normal Structure Flashcards

1
Q

2 types of bone?

A
  1. Cortical Bone

2. Cancellous Bone

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2
Q

Percent of Cortical Bone? Turn over rate? Density and packed with what?

A

80% of bone. Slow turn over. Dense and packed with haversian canal system.

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3
Q

Haversion System aka?

A

Osteon

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4
Q

What and where is the Haversian Canal? In which type of bone? Communicates with what?

A

Central canal of Cortical Bone. Contains blood vessels and nerves that communicate with periosteum.

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5
Q

Lamelle are found where, what shape, and in what type of bone?

A

Concentric layers of bone surrounding Central/Haversian Canal. In Cortical Bone.

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6
Q

Osteocytes are found where and active in what functions?

A

Within Lamelle (concentric layers around Central/Haversian Canal) on Cortical Bone. Active in signaling, maintenance, and turn-over.

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7
Q

What is Volkman’s Canal and in which type of canal? What does it connect to?

A

Horizontal canal in cortical bone. Connects to periosteum.

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8
Q

Cancellous Bone described as ____ or ____

A

Trabecular or spongy bone

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9
Q

What % is Cancellous bone? Density? Turnover rate?

A

20% of bone. Less dense than cortical bone but large surface area. High turnover rate.

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10
Q

Cancellous Bone undergoes remodeling along what/where?

A

Along lines of stress

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11
Q

What is Wolff’s Law?

A

Increased mechanical stress will increase bone density

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12
Q

Describe the Periosteum. Where is it?

A

Thin, double-layered, tough fibrous membrane. Layer that surrounds bone.

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13
Q

Where does Periosteum cover and not cover? (Hint: 2 places)

A

Covers all bone EXCEPT at ligament or tendon insertion sites.

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14
Q

Periosteum does not cover at which two places?

A
  1. Ligament insertion sites

2. Tendon insertion sites

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15
Q

Outer layer of Periosteum contains what two things?

A
  1. Capillaries

2. Nerves

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16
Q

What fiber does Inner Layer of Periosteum contain? What does it do? Includes what two things?

A

Sharpey’s Fibers. Anchors Periosteum to Cortical Bone. Includes tendons and ligaments.

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17
Q

What contained if inner layer of Periosteum is active? Inactive?

A

Active=Osteoblasts

Inactive=Fibroblasts (can become osteoblasts)

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18
Q

Where and what are fibroblasts?

A

Within inactive inner layer of periosteum. Can become osteoblasts if new growth needed.

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19
Q

Bone Marrow aka? Where confined to?

A

Myeloid Tissue. Confined to cavities between osseus component of bone.

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20
Q

General function and regions/types of bone marrow?

A

Function=Form new blood cells

  1. Red (active)
  2. Yellow (Inactive)
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21
Q

Where is Red Bone Marrow? Do all bone have it?

A

Found in trabecular or spongy bone regions (cancellous bone). Not all bones have it. Found in: Pelvis, vertebra, cranium, manubrum, sternum, ribs, and humerus

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22
Q

Where is Yellow Bone Marrow? What does it represent?

A

Found in medullary cavity of long bone. Inactive. Represents fatty cells.

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23
Q

What is the name of the artery which supplies the primary source of blood to bones? Where on the bone do they enter?

A

Nutrient arteries. Enter in middle of diaphysis.

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24
Q

What can a fracture cause a bone to become? Which bones are most likely or “precious”?

A

Necrotic.
Prox humerus, prox femus, scaphoid, talus, and base of 5th metatarsal are “precious” bones which can become necrotic from a fx

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25
Q

What are the two main components of blood?

A
  1. Cellular component

2. Extra Cellular Matrix component

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26
Q

What are the three “osteos” of the Cellular Component of bone?

A
  1. Osteoblasts
  2. Osteoclases
  3. Osteocytes
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27
Q

What long list of things makes up the Extra Cellular Matrix component of bone?

A

Collagen, ECM proteins, proteoglycans, cytokines, growth factors, minerals, etc

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28
Q

Osteoprogenitor cells make what?

A

Osteoblasts

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29
Q

Osteoblasts comes from which cells? Where are Osteoblasts located?

A

From osteoprogenitor cells. Located on bone surfaces and inner surface of periosteum.

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30
Q

Osteoblasts located on bone surfaces (Haversian Canal, trabecular) and innersurface of periosteum are what?

A

Metabolically active

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31
Q

Osteoblasts located in deeper bone are what? How can that change?

A

Metabolically inactive until stimulated by physical disruption (Trauma, fx, etc)

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32
Q

What is the function of Osteoblasts and what do they make?

A

Form new bone. Make non-mineralized matrix (osteoid) for new bone formation.

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33
Q

What cells do Osteoblasts regulate?

A

Osteoclasts

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34
Q

Osteocytes are formed from what cell?

A

Osteoblasts

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35
Q

When does an Osteoblast become an Osteocyte?

A

When the surrounding bone matrix (osteoid) is mineralized

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36
Q

What is the name of the small cavity where osteocytes are located?

A

Lacunae

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37
Q

What are the majority of cells in the bone?

A

Osteocytes

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38
Q

What is the function of osteocytes?

A

Stimulate bone remodeling process by secreting enzymes which dissolve surrounding bone mineral and prepare for remodeling.

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39
Q

What do osteocytes sense?

A

Mechanical stimulants

40
Q

What do osteocytes maintain?

A

Homeostasis of mineralized bone (calcification). P and Ca concentrations, receive nutrients from capillary blood.

41
Q

Osteocytes are stimulated by these two, inhibited by this one, and communicate with others by what?

A

Stimulated= Calcitonin, physical stress
Inhibited= PTH
Communicate via= Gap junctions in canaliculi

42
Q

Where are Osteoclasts located? What do they represent?

A

In Howship’s Lacunae. Represent areas of bone resorption.

43
Q

What is the function of Osteoclasts?

A

Resorption of bone

44
Q

What are the steps in osteoclast of bone resporption/break down?

A

Migrate and attach to bone, secrete acid and lytic enzymes, bone elements absorbed into osteoclast from microvilli, byproducts released into blood stream.

45
Q

What happenst to the Osteoclast after resorption of bone?

A

Either goes dormant until needed again or apoptosis

46
Q

What three things and conditions can Osteoprogenitor cells become?

A
  1. Osteoblasts under low strain and high oxygen conditions
  2. Cartilage under medium strain and low oxygen conditions
  3. Fibrous tissue under high strain
47
Q

What are the two broad components of the ECM?

A
  1. Organic components

2. Inorganic components

48
Q

Collagen FIbers, Proteoglycans, ECM proteins, and Cytokines/growth factors are examples of what?

A

Organic components of bone ECM

49
Q

What makes Type 1 Collagen, what percent of organic component is it, and function?

A

Synthesized and secreted by Osteoblasts. 90% of organic component. Tensile strength of bone.

50
Q

What are the functions of Proteoglycans, an organic component of bone ECM?

A
  1. Modulate fluid balance within bone by attracting calcium (via ion exchange)
  2. Compressive strength of bone
51
Q

What is the function of ECM proteins, an organic component Of bone ECM?

A

Mineralization and bone formation

52
Q

What are the 4 types of proteins involved in bone matrix?

A
  1. Osteocalcin
  2. Osteonectin
  3. Osteopontin
  4. Bone Almbuin
53
Q

What is the function of Osteocalcin? What does it stimulate/attract? Where is this protein found and produced by what?

A

Regulation of bone density. Stimulates/attracts osteoclastic activity. Found in in bone matrix, produced by mature osteoblasts.

54
Q

What stimulates Osteocalcin? What inhibits?

A

Stimulates=1,25 dihydroxyvitamin D3

Inhibits=PTH

55
Q

Osteonectin and Osteopontin have a role in what?

A

Role bone mineralization

56
Q

What are the two functions of Bone Albumin? Where is it found?

A

Found in bone matrix.

  1. Interstitial fluid balance of bone
  2. Transports hormones, ions, and other metabolites to/from bone cells
57
Q

Where are Cytokines and Growth Factors? What is their function?

A

Embedded in matrix of bone.

Regulation/signaling for differentiation, activation, growth, and bone turnover.

58
Q

Function of Bone Morphogenic Proteins? Where?

A

Embedded in bone matrix. Promote formation of osteoblasts from stem cells, osteogenesis in osteoblasts. Fills hole in bone that osteoclasts make.

59
Q

What is organic bone component? What are the two that make them up?

A

Minerals. HAP and Calcium Phosphate.

60
Q

What and where is Calcium Hydroxyapatite? What is it’s function?

A

Mineral which makes up inorganic bone component. Insoluable crystal that deposits in collagen fibers. Function in compressive strength of bone.

61
Q

What are the two types of Bone Formation?

A
  1. Intramembranous Ossification

2. Endochondral Ossification

62
Q

What kind of bones does Intramembranous Ossification form and where? What does it form without?

A

Forms “flat” bones in skull, face, mandible, and clavicle.

Forms without cartilage model.

63
Q

What are the four steps of Intramembranous Ossification (long version, look at next card for short)?

A
  1. Cluster of osteoblasts forms ossification center within fibrous connective tissue membrane
  2. Osteoblasts secrete boney matrix in surrounding fibrous membrane which calficies and traps in osteoblasts
  3. Formation of trabeculae - osteoid form around invaginating blood vessels. Periosteum forms from mesenchyal cells.
  4. Bone collar of compact bone forms. Red marrow forms in trabeculae.
64
Q

What are the four steps of Intramembranous Ossification? (short version)

A
  1. Osteoblasts form ossification center in fibrous connective tissue
  2. Crank our matrix to start clump of bone
  3. Forma trabeculae and gets blood supply
  4. Red marrow formed
65
Q

What is Endochondral Ossification? What is its model? What replaces what?

A

Cartilage model of bone growth/formation. Bone replaces cartilage (cartilage does not become bone)!

66
Q

Endochondral Ossification is responsible for which two kinds of bone growth?

A
  1. Longitudional bone growth during development

2. Appositional growth “widening” during VERY early development (when baby)

67
Q

What are the two cartilaginous areas in an immature bone of Endochondral Ossification? Where are they located and what growth allows?

A
  1. Sphere Zone=around end of epiphysis. Allows growth of epiphysis.
  2. Physis (epiphyseal plate)=between metaphysis and epiphysis. Allows for longitudional growth. AKA growth plate.
68
Q

Growth plate aka? On which kind of bone?

A

Epiphyseal Plate. On longitudional bone during growth.

69
Q

Where and when are Chondrocytes found?

A

In the Endochonrial Ossification “Reserve Zone”. Earliest step.

70
Q

What happens during Appositional Growth? What shape of bones does it happen to?

A

Long bones widen.

71
Q

Age range when Growth Plates (epiphyseal plates) fuse? Any difference in male vs female?

A

14-21. Female earlier due to puberty.

72
Q

What percent of the spine is full grown by age 8? Which grows faster in childhood -extremeties or axial skeleton?

A

80% by age 8.

Extremeties grow faster.

73
Q

Osteoperosis is when what happens to osteoblasts and osteoclasts?

A

More osteoclastic activity than osteoblastic activity.

74
Q

What are the 5 stages of bone remodeling?

A
  1. Activation
  2. Resorption
  3. Reversal
  4. Formation
  5. Quiesence
75
Q

What is the stimulus and action of the Activation Phase of Bone Remodeling?

A

Stimulus: Anything that is probone growth. Hormone, drug, or physical stimulus.

Action: Activates resting osteoblasts to signal activation of osteoclastic activity.

76
Q

What happens on the Resorption Phase of Bone Remodeling? In Compact Bone and Cancellous bone?

A

Osteoclasts breakdown bone and make resorption cavity.

Compact bone= cavity follows longitudional axis of Haversian canal
Cancellous bone=follows surface of trabeculae

77
Q

What two hormones can slow/inhibit creating the resorption cavity in the Resorption Phase of Bone Remodeling?

A

Calcitonin and Estrogen

78
Q

What do post-menopausal women lack that affects bones?

A

Lack Estrogen which allows osteoclasts to continue breaking down bone and prolong resorption.

79
Q

What does Acidosis do to osteoclast resorption?

A

Promotes osteoclast resorption

80
Q

Which cell upregulates and downregulates osteoclast activity?

A

Osteoblasts

81
Q

Bone resorption is performed by which cell? What stimulates it?

A

Performing by active osteoclasts. Stimulates by RANKL, PTH, and other molecules.

82
Q

Bone formation is performed by what two things/processes?

A
  1. Inhibiting osteoclasts

2. Stimulating osteoblasts

83
Q

What inhibits Osteoclasts during bone formation?

A

OPG

84
Q

What does Osteoclast activation stimulate?

A

Bone resportion

85
Q

What are two molecules that stimulate bone resorption?

A
  1. RANKL

2. PTH

86
Q

RANKL ligand is secreted by what two things and where does it bind to? What does it activate?

A

Secreted by Osteoblasts and Tumor Cells. Binds to RANK receptor on osteoclast precursor and mature osteoclast cells.

Activates osteoclasts.

87
Q

What does PTH immediately stimulate in health bone? What does it stimulate in the long term?

A

Immediate=Short-term Ca++ release from bone fluid

Long-term=Stimulates osteoblasts to produce/release RANKL which stimulates osteoclasts

88
Q

PTH can also be secreted by tumor cells and cause what?

A

Excess signaling of osteoclast resorption

89
Q

What does Interluken-1 (IL-1) stimulate and cause? Where found?

A

Stimulates osteoclast differentiation which leads to bone resorption. Found near loose total joint implants which stimulate osteoclasts.

90
Q

What does Osteoclast inhibition do to bones?

A

Decreases bone resorption

91
Q

5 Molecules that inhibit bone resorption?

A
  1. OPG
  2. Calcitonin
  3. Estrogen
  4. IL-10
  5. Transforming Growth Factor Beta
92
Q

What are OPG and how do they work? What produces them?

A

Inhibit bone resorption. Produced by Osteoblasts. Decoy receptors which bind to RANKL. Inhibit osteoclast differentiation, fusion, and activation.

93
Q

What does Calcitonin do?

A

Inhibit bone resorption by decreasing calcium. Inhibit number and activity of osteoclasts.

94
Q

What does Estrogen do to osteoclasts?

A

Inhibit bone resorption. Stimulates bone production and prevents resorption. Suppresses osteoclasts.

95
Q

Osteolytic Bone Metastasis mediated by which pathway? Cancer cells directly produce what?

A

Mediated by RANK and RANKL pathway. RANKL produced directly by cancer cells.