Bone Metabolism

Question 1

What type of bone is most susceptible to Osteoporosis? Why?

Answer 1

Trabecular; turn over quicker (break down/rebuild cycle); With age, build up cannot keep up with break down

Question 2

Which bones are Trabecular bones

Answer 2

Hips, feet, hands, elbows, vertebrae, wrists

Question 3

What is the function of Osteoblasts

Answer 3

Bone formation

Question 4

What is the function of Osteoclasts

Answer 4

Break down bones

Question 5

What is the function of Calcitonin

Answer 5

Lowers blood Calcium by opposing PTH, inhibiting Osteoclast activity and increasing Calcium secretion in urine

Question 6

What is the function of Osteocalcin

Answer 6

Attracts Calcium to be deposited into bones; secreted by Osteoblasts

Question 7

What is the function of Glucocortids in Bone Metabolism

Answer 7

Reduce Calcium absorption & Osteoblast activity; anti-inflammatory steroids

Question 8

What secretes Osteocalcin

Answer 8

Osteoblasts

Question 9

What are Glucocortids

Answer 9

Anti-inflammatory steroids; long-term exposure can lead to Osteomalacia or growth failure in children

Question 10

What is the function of Thyroid Hormone in Bone Metabolism

Answer 10

Increase bone resorption

Question 11

What is the function of Growth Hormone in Bone Metabolism

Answer 11

Stimulate Calcium deposition into bones

Question 12

What is the function of Estrogen in Bone Metabolism

Answer 12

Inhibits Osteoclast activity when bound to bones

Question 13

What secretes Calcitonin

Answer 13

Thyroid

Question 14

What activates Bone Turnover Cycle

Answer 14

Osteoclasts secrete lysosymes to breakdown (dissolve) calcium phosphate (hydroxyapatite) in bones; also secrete collagenase to dissolve protein backbone; “Cement of bones”; bone resorption

Question 15

How long does osteoclast activity last in Bone Turnover Cycle

Answer 15

10-20 days

Question 16

What is the next step in the Bone Turnover Cycle after Osteoclast activity (Step 2)

Answer 16

Osteoblasts deposit minerals; bone formation

Question 17

How long does osteoblast activity last in the Bone Turnover Cycle

Answer 17

3-6 months

Question 18

What is the next step in the Bone Turnover Cycle after Osteoblast activity (Step 3)

Answer 18

Resting phase

Question 19

How long does the resting phase last in the Bone Turnover Cycle

Answer 19

months-years before resorption begins again

Question 20

What are markers of bone formation (in the blood)

Answer 20

Osteocalcin, Bone-specific alkaline phosphatase, Procollagen peptides

Question 21

What are markers of bone resorption (in the urine)

Answer 21

Hydroxyproline, Hydroxylsine glycosides, Pyridinium crosslinks

Question 22

What does high Osteocalcin in the blood indicate

Answer 22

Bone formation

Question 23

What does Hydroxyproline in the urine indicate

Answer 23

Bone resorption (collagen breakdown)

Question 24

When does Osteoporosis occur

Answer 24

When there is more bone break down than build up

Question 25

What are the health concerns with Osteoporosis

Answer 25

Increased risk of breaking bones; potentially effect blood Calcium and other Calcium functions; hunching could effect lung capacity, increasing pneumonia risk

Question 26

What is the concern with bone breaking in Osteoporosis patients

Answer 26

Bone healing takes a long time, decreases quality of life, muscle atrophy, decreases mortality

Question 27

At what stage do the size of bones stop growing

Answer 27

Puberty

Question 28

At what stage does the density of bones stop building (peak bone mass)

Answer 28

Age 30

Question 29

Why is fracture threshold higher in women

Answer 29

Bone mass lower to begin with, experience steeper decline rate

Question 30

How does smoking effect bones

Answer 30

Encourages osteoclasts

Question 31

How can osteoblasts be stimulated

Answer 31

Pressure - weight training/exercise

Question 32

What is BMD compared with for measuring Osteoporosis during DXA testing

Answer 32

Compare current measurement with someone younger, same gender for osteoporosis diagnosis; Within age, gender and ethnicity group also measured

Question 33

Osteoporosis vs Osteomalacia

Answer 33

Remodeling imbalance;more breakdown than buildup vs Remineralization low;supply problem (VitD or Calcium;intake or kidney/liver function impaired)

Question 34

What is similar between Osteoporosis and Osteomalacia

Answer 34

Low bone mineral density (BMD)

Question 35

What can be tested to differentiate between Osteoporosis and Osteomalacia

Answer 35

Dietary intake, serum Hydroxyprolene, serum VitD, PTH levels