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Pathophys II MHM - Exam 1 > MSK Module 1B > Flashcards

MSK Module 1B Flashcards

1
Q

All connective tissue is composed of:

A
  • Cellular component

- Extracellular matrix (with a non-fibrous and fibrous component)

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2
Q

Bone tissue consists of:

A
  • Cellular component (osteoblasts, osteocytes, osteoclasts)

- Matrix component (collagen, proteoglycans, BMPs, glycoproteins, etc.)

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3
Q

Cell types found in bone:

A

Osteoblasts
Osteoclasts
Osteocytes

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4
Q

What do osteoblasts produce?

A
  • Type 1 collagen

- Non-mineralized bone matrix (osteoid)

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5
Q

Function of osteoblasts

A

Formation of new bone:

  • Produces substances involved
  • Facilitates mineralization of osteoid to complete the process
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6
Q

When is an osteoblast considered an osteocyte?

A

Once the osteoid (surrounding bone matrix) is mineralized

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7
Q

Osteoblasts are located along:

A
  • Trabecular surfaces
  • Inner surface of Haversian canal
  • Inner surface of periosteum
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8
Q

Osteocytes are formed from:

A

Osteoblasts

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9
Q

Where are osteocytes located?

A

Lacunae (small cavity)

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10
Q

Osteocytes make up approx. ___% of cells in mature human skeleton

A

90

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11
Q

Are osteocytes active or inactive?

A

Active in monitoring/maintaining bone status

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12
Q

Functions of osteocytes

A
  • Stimulate remodeling process
  • Serve as mechanism for mechanical stimulus to bone
  • Maintain homeostasis of the mineralized bone
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13
Q

Where are osteoclasts located?

A

Howship’s lacunae

depressions seen in microscopic view that represent areas of bone resorption

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14
Q

How do osteoclasts resorb bone?

A
  • Secrete acid and lytic enzymes to dissolve surrounding bone
  • Elements of bone are resorbed into ossteoclast at base of microvilli
  • Releases bony elements into capillaries to be recycled
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15
Q

What happens to an osteocyte after it is resorbed by osteoclasts?

A

Either degenerates or becomes dormant until needed again

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16
Q

What is bone matrix composed of?

A 
Type 1 collagen (90%)
Proteoglycans
BMP (bone morphic protein)
Glycoproteins
Osteocalcin
Bone albumin
GFs
Bone minerals
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17
Q

What is Type 1 collagen’s function within bone?

A
  • Tensile strength of bones

- Weight bearing (compressive) strength

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18
Q

What are proteoglycans? Function?

A
  • Part of bone matrix
  • Large polysaccharides attached to protein
  • Located b/w collagen fibers
  • Plays role in calcification/fluid balance by attracting calcium
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19
Q

Function of bone morphic proteins (BMP)?

A
  • Promote formation of osteoblasts from stem cells
  • Promote osteogenesis in osteoblasts
  • Promote bone repair
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20
Q

Function of glycoproteins in bone?

A
  • Assist in collagen fiber formation

- May assist in calcification

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21
Q

What is osteocalcin?

A
  • Part of communication b/w osteoblasts and clasts
  • Produced by osteoblast
  • Promotes osteoclast activity
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22
Q

What does bone albumin do?

A
  • Attracts fluids and maintains fluid balance in bone

- Transports hormones, ions, other metabolites to/from bones

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23
Q

What do growth factors (GFs) do in bone?

A

Play role in differentiation, activation, growth, and turnover of bone (and other tissue)

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24
Q

What is calcium hydroxyapatite (HAP) and what does it do?

A
  • Bone mineral
  • An insoluble crystal that deposits within the collagen fibers
  • End stage of calcium crystallization for mineralization
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25
Q

Bone multicellular unit

A
  • Cluster of cells that breakdown an area of bone surface and then fills it with new bone
  • Multiple BMU clusters are activated/inactivated at any given point in time and in different locations
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26
Q

6 steps of bone remodeling

A
  1. Activation of BMU
  2. Initiation of osteoclastic activity
  3. Resorption forms small cavity
  4. Osteoblast maturation/recruitment
  5. Osteoid formation
  6. Maturation of osteoid
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27
Q

What does RANK-L do?

A

Signals pre-osteoclasts to mature into active osteoclasts

28
Q

What does osteoprotogerin do?

A

Inhibits RANK-L

29
Q

How do estrogen and calcitonin affect bone remodeling?

A

Inhibit osteoclast activity

30
Q

How does acidosis affect bone remodeling?

A

Promotes osteoclast resorption

31
Q

What are metabolic disorders of bone?

A
  • Osteoporosis
  • Osteomalacia
  • Paget’s disease
32
Q

Name the osteochondroses

A
  • Osteonecrosis (avascular)

- Apophysitis (epiphysitis)

33
Q

Osteopenia

A
  • Low bone mineral density (BMD)

- Between 1 and 2.5 SD below the young adult mean

34
Q

Osteoporosis

A
  • Severe decrease in BMD
  • 2.5 SD or more below young adult mean
  • Osteoclast activity is greater than osteoblast activity
35
Q

Osteomalacia

A
  • “Softening” of the bone

- Insufficient mineralization (no loss of bone)

36
Q

Osteopetrosis

A

Increased BMD

37
Q

Primary osteoporosis

A
  • Unrelated to any underlying disease
  • Type 1 (postmenopausal, cancellous bone)
  • Type 2 (age related, both cortical and cancellous bone)
38
Q

Secondary osteoporosis

A

Secondary to medication or disease

39
Q

3 phases of bone mass

A

Growth - 90% of bone density is reached here
Consolidation - remaining 10% of bone density gained
Involution - gradual loss of bone

40
Q

When is peak bone mass commonly reached?

A

By 30 years old

41
Q

Age related rate of bone density loss is greater in males, less in males, or equal between both?

A

Equal

42
Q

How much bone mass is loss per year due to age?

A

Approx. 0.5-1% each year

43
Q

Rate of bone loss in women is ___ after menopause

A

Accelerated (approx. 3-5% per year)

44
Q

Estrogen loss in menopause affects which players in bone remodeling?

A
  • Higher levels of RANK-L (promotes maturation of osteoclasts)
  • Reduced levels of OPG (inhibits maturation)
45
Q

Menopause affects which type of bone most significantly?

A

Cancellous (trabecular)

*Vertebrae, metaphysis of long bones

46
Q

Which drugs in particular can cause secondary osteoporosis?

A
  • Corticosteroids

- Immunosuppressants

47
Q

Why is trabecular bone very sensitive to conditions that alter osteoblast/clast activity?

A
  • Larger surface area and not as large mass to begin with compared to cortical bone
  • Experiences greater loss
48
Q

How does tobacco increase risk for osteoporosis?

A

Impairs bone progenitor cells (inhibiting osteoblast activity)

49
Q

How does alcohol increase risk for osteoporosis?

A
  • Impairs osteoblast activity
  • Impairs Ca absorption
  • Increases renal excretion of Ca
50
Q

What is the female triad?

A
  • Eating disorder
  • Amenorrhea
  • Osteoporosis
51
Q

A decrease in 1 SD of BMD will increase risk of fracture by:

A

1.5 to 3x

52
Q

What is the gold standard for diagnosing osteoporosis?

A

DEXA

53
Q

Why is x-ray a poor screening tool for osteoporosis?

A

It only detects bone loss after significant loss has occurred

54
Q

What is Rickets?

A

Childhood osteomalacia

55
Q

What type of fractures are seen with osteomalacia?

A

“Looser’s zones” or milkman’s pseudofractures

56
Q

Describe Paget’s disease and epidemiology

A
  • Disease that results in bone deformation
  • Excessive resorption is followed by excessive bone formation
  • Onset 50+ yo
  • Males more than females
57
Q

Describe osteonecrosis (avascular necrosis)

A
  • Death of bone due to loss of blood supply
  • Often no symptoms
  • Femoral head is MC site
58
Q

What is apophysitis and what are common examples?

A
  • A traction apophysitis of the secondary ossification center
  • Osgood-Schlatter disease (patella tendon pulling on tibial tuberosity)
  • Olecranon (throwing athletes)
  • Sever’s disease (Achille’s)
59
Q

What is osteomyelitis?

A

Inflammation of bone caused by bacteria or other infectious agents

60
Q

What is exogenous osteomyelitis?

A

Trauma exposes bone to bacteria and other foreign material

61
Q

What is endogenous osteomyelitis?

A

Infection spreads to bone from pre-existing systemic infection (S. aureus is common)

62
Q

How does osteomyelitis occur?

A
  • The physical arrangement of bone contains regions that immune defense mechanisms are unable to access
  • This makes bones susceptible to infection if bacteria gains access
63
Q

How does osteomyelitis form in children?

A

Sequestrum (piece of dead bone) and involucrum (layer of new bone) formation

64
Q

How does bone respond to a primary benign tumor?

A

Forms a sclerotic rim in order to contain the tumor

*These do NOT tend to cause pain like malignant tumors

65
Q

Bone tumor descriptions on imaging

A
  • Geographic (well defined margins)
  • Moth eaten (less defined margins)
  • Permeative (poor margins)

Pathophys II MHM - Exam 1 (9 decks)

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