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Histology > Lecture 1-Bone > Flashcards

Lecture 1-Bone Flashcards

1
Q

How is bone elastic and dynamic?

A

Secretory and regulatory functions.
Ca homeostasis for body
Self-repairing
Storage and production of blood and immune system components

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2
Q

Bones plastic properties are _______

A

absorbs and stores compressional forces

absorbs, transmits, and stores tensile forces

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3
Q

what is bone composed of?

A

calcium and phosphorus crystals in framework of protein fibers (primarily collagen)

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4
Q

Composition of bone breaks down to ______

A

70% mineral
5% water
30% organic compounds

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5
Q

3 bone cells

A

osteoblasts
osteoclasts
osteocytes

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6
Q

What do osteoblasts do?

A
  • produce structural and noncollagenous proteins to rapidly build osteoid matrix
  • produce regulatory factors that degrade ECM and prepare it for calcification
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7
Q

What are the proteins and regulatory factors produced by osteoblasts?

A

Proteins - Type I collagen, proteoglycans

Factors - cytokines, growth factors, prostaglandins, enzymes

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8
Q

What do osteocytes do?

A

Continues producing osteoid matrix

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9
Q

What do osteoclasts do?

A

bone dissolution and absorption

maintain normal blood calcium homeostasis

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10
Q

Function of Marrow?

A

Fills intratrabecular space

primitive stem cell site from which all cellular elements of blood derive

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11
Q

Two type of marrow

A

Red and Yellow

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12
Q

Yellow marrow function

A
  • stores energy and hormones which make bone a storage organ capable of converting fat to energy
  • reserves hematotrophic tissue to be delivered to blood in case of injury
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13
Q

2 types of bone

A

cortical

trabecular

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14
Q

More vulnerable to disturbances in bone remodeling process.

Compression is predominant external force

A

trabecular bone

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15
Q

Structural unit of compact bone?

A

osteon

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16
Q

composed of vascular channels circumferentially surrounded by lamellar bone

A

Haversion bone

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17
Q

Most responsive to bending and torsional forces

A

cortical bone

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18
Q

Bone metabolism and structure responds to two signals….

A

piezoelectric and streaming potentials

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19
Q

what produces potentials in piezoelectric materials?

A

strain (stretch)

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20
Q

what produces streaming potentials?

A

deformation as a result of electrolyte fluid flow

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21
Q

positive charges stimulates _________

A

osteoblastic activity for new bony matrix

22
Q

negative charges stimulates _________

A

osteoclastic activity = bone resorption

23
Q

3 chemicals that maintain tight control on bone homeostasis…

A

Vitamin D3 metabolites
PTH
calcitonin

24
Q

optimal stimulus for formation and regeneration of bone…..

A

modified compression in the line of stress

line of stress is internal trabecular system

25
Q

Factors that stimulate bone synthesis

A 
WB and use of anti-gravity muscles
Estrogen
Testosterone
Growth Hormone
Thyroid Hormone
Nutrition
Vitamin D/sunshine
26
Q

Factors associated with bone absorption

A

Lack of WB and decreased use of anti-gravity muscles
Glucocortoids (decrease Ca absorption)
Excessive Thyroid hormone
PTH

27
Q

PTH stimulates __________

A

osteoclasts

28
Q

what is a pseudoarthosis?

A

false joint, articular cartilage can develop on two surfaces of fracture line due to OSR for cartilage taking place

29
Q

two dysfunctional bone remodeling responses

A

bone spurs, osteophytes

30
Q

How is an osteophyte formed?

A

abnormal shearing forces when attempting to stabilize a region.

31
Q

How is a bone spur formed?

A

as ligaments attempt to restrict an unstable joint, increased tension on the bone will lead to growth along line of ligaments pull

32
Q

osteoporosis associated with an accelerated and disproportionate trabecular bone loss

A

Type I

33
Q

osteoporosis associated with proportionate loss of both cortical and trabecular bone

A

Type II

34
Q

Common age-related changes affecting bone loss are:

A
  • gradual increase in PTH as result of chronic Ca deficiency
  • decreased intestinal absorption of elemental CA
  • lower circulating calcitonin
  • decreased sunlight exposure and vit D in diet
  • decreased ovarian function
  • increase production of bone resorbing cytokines
35
Q

1 determinant of age related bone loss in men

A

decreased mechanical loading

36
Q

How does fat play a role in osteoporosis?

A

Androgen chemically converts estrogen in fatty tissues
more fat = more estrogen can be produced
reduces a risk in osteoporosis

37
Q

Factors that aggravate age-related bone loss

A 
Thyroid imbalance
Hyperparathyroidism
Glucocorticoid therapy
Malabsorption syndromes
Excessive use of aluminum-containing antacids
Certain diseases
38
Q

Factors that can contribute to increased risk of fx

A 
Slender build
fair skin
family history
small muscle mass
sedentaryt
small peak adult bone mass
low Ca intake
smoking
excessive protein, Na, and alcohol
one or more prior osteoporotic fx
while female reaches ago 60
increase likelihood of falls
oral contraception
39
Q

Primary prevention of osteoporosis before age 30 is

A

increasing peak adult bone mass

40
Q

Contraindicated exercises for someone who are known or expected to have osteoporosis are…..

A

forceful jumping or twisting movements
flexion exercises
trunk rotation exercises or sports
forceful unguarded movements

41
Q

What is the effect of weight bearing on bone resorption?

A

WB influences the activity of osteoblasts

42
Q

What is the effect of abnormal stresses on bone remodeling?

A

Results in osteophytes and bone spurs

43
Q

What are the effects of genetics on rate of bone loss?

A

heavy boned persons are relatively immune to osteoporotic fxs

44
Q

What are the effects of mechanics on rate of bone loss?

A

increased loading generally results in increased bone mass and decreased loading results in decreased bone mass

45
Q

How does estrogen effect bone remodeling?

A

Regulates interleukin-1 which stimulates bone resorption and IL-6 (powerful bone resorbing cytokine
- prevents bone loss by suppressing the release of cytokines

46
Q

How does PTH effect bone remodeling?

A
  • Released PTH leads to more efficient intestinal absorption of ingested Ca and renal reabsorption of Ca
  • Elevated PTH increase basal rate of bone remodeling
  • Increase PTH follows a decrease in Ca intake.
  • Bone remodeling rate will be enhanced but there will be bone loss
47
Q

How does growth hormone effect bone remodeling?

A

General trophic effect on skeleton

Stimulates remodeling

48
Q

What is the most common ways for measuring bone mass and rate of bone loss?

A

Bone mineral density scans
BMD correlated with bone strength
BMD correlated with fracture risk

49
Q

Secondary way of preventing osteoporosis….

A

limiting the rate of bone loss later in life especially through dietary measures, vitamins, and exercise

50
Q

How does low does estrogen replacement therapy provide an effective way of reducing bone loss with menopause?

A

It enhances conservation of ingested calcium

51
Q

What non-hormonal meds are sometimes used as therapy for post-menopausal osteoporosis?

A

Microcrystalline Hydroxyaptite

Calcium Citrate

Histology (2 decks)

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