Lecture 1-Bone

Question 1

How is bone elastic and dynamic?

Answer 1

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

Question 2

Bones plastic properties are _______

Answer 2

absorbs and stores compressional forces

absorbs, transmits, and stores tensile forces

Question 3

what is bone composed of?

Answer 3

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

Question 4

Composition of bone breaks down to ______

Answer 4

70% mineral
5% water
30% organic compounds

Question 5

3 bone cells

Answer 5

osteoblasts
osteoclasts
osteocytes

Question 6

What do osteoblasts do?

Answer 6

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

Question 7

What are the proteins and regulatory factors produced by osteoblasts?

Answer 7

Proteins - Type I collagen, proteoglycans

Factors - cytokines, growth factors, prostaglandins, enzymes

Question 8

What do osteocytes do?

Answer 8

Continues producing osteoid matrix

Question 9

What do osteoclasts do?

Answer 9

bone dissolution and absorption

maintain normal blood calcium homeostasis

Question 10

Function of Marrow?

Answer 10

Fills intratrabecular space

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

Question 11

Two type of marrow

Answer 11

Red and Yellow

Question 12

Yellow marrow function

Answer 12

• 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

Question 13

2 types of bone

Answer 13

cortical

trabecular

Question 14

More vulnerable to disturbances in bone remodeling process.

Compression is predominant external force

Answer 14

trabecular bone

Question 15

Structural unit of compact bone?

Answer 15

osteon

Question 16

composed of vascular channels circumferentially surrounded by lamellar bone

Answer 16

Haversion bone

Question 17

Most responsive to bending and torsional forces

Answer 17

cortical bone

Question 18

Bone metabolism and structure responds to two signals….

Answer 18

piezoelectric and streaming potentials

Question 19

what produces potentials in piezoelectric materials?

Answer 19

strain (stretch)

Question 20

what produces streaming potentials?

Answer 20

deformation as a result of electrolyte fluid flow

Question 21

positive charges stimulates _________

Answer 21

osteoblastic activity for new bony matrix

Question 22

negative charges stimulates _________

Answer 22

osteoclastic activity = bone resorption

Question 23

3 chemicals that maintain tight control on bone homeostasis…

Answer 23

Vitamin D3 metabolites
PTH
calcitonin

Question 24

optimal stimulus for formation and regeneration of bone…..

Answer 24

modified compression in the line of stress

line of stress is internal trabecular system

Question 25

Factors that stimulate bone synthesis

Answer 25

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

Question 26

Factors associated with bone absorption

Answer 26

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

Question 27

PTH stimulates __________

Answer 27

osteoclasts

Question 28

what is a pseudoarthosis?

Answer 28

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

Question 29

two dysfunctional bone remodeling responses

Answer 29

bone spurs, osteophytes

Question 30

How is an osteophyte formed?

Answer 30

abnormal shearing forces when attempting to stabilize a region.

Question 31

How is a bone spur formed?

Answer 31

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

Question 32

osteoporosis associated with an accelerated and disproportionate trabecular bone loss

Answer 32

Type I

Question 33

osteoporosis associated with proportionate loss of both cortical and trabecular bone

Answer 33

Type II

Question 34

Common age-related changes affecting bone loss are:

Answer 34

- 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

Question 35

#1 determinant of age related bone loss in men

Answer 35

decreased mechanical loading

Question 36

How does fat play a role in osteoporosis?

Answer 36

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

Question 37

Factors that aggravate age-related bone loss

Answer 37

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

Question 38

Factors that can contribute to increased risk of fx

Answer 38

``` 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 ```

Question 39

Primary prevention of osteoporosis before age 30 is

Answer 39

increasing peak adult bone mass

Question 40

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

Answer 40

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

Question 41

What is the effect of weight bearing on bone resorption?

Answer 41

WB influences the activity of osteoblasts

Question 42

What is the effect of abnormal stresses on bone remodeling?

Answer 42

Results in osteophytes and bone spurs

Question 43

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

Answer 43

heavy boned persons are relatively immune to osteoporotic fxs

Question 44

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

Answer 44

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

Question 45

How does estrogen effect bone remodeling?

Answer 45

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

Question 46

How does PTH effect bone remodeling?

Answer 46

- 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

Question 47

How does growth hormone effect bone remodeling?

Answer 47

General trophic effect on skeleton | Stimulates remodeling

Question 48

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

Answer 48

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

Question 49

Secondary way of preventing osteoporosis....

Answer 49

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

Question 50

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

Answer 50

It enhances conservation of ingested calcium

Question 51

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

Answer 51

Microcrystalline Hydroxyaptite | Calcium Citrate