Ch 13: Bone Health,

Question 1

trabecular/spongy bone

Answer 1

• more porous, less dense found inside bone

- affected more by osteoporosis

Question 2

cortical/compact bone

Answer 2

more dense found on outside of bone

Question 3

bone mineral density = ?

Answer 3

bone strength

Question 4

bone composition

Answer 4

55% mineral for strength

45% collagen for flexibility

Question 5

how long do bones grow for?

Answer 5

bone density accrues into early adulthood

Question 6

osteoblast

Answer 6

builds bone

Question 7

osteoclast

Answer 7

breaks down bone

with age, clast activity > blast activity

Question 8

roles of calcium

Answer 8

• most abundant mineral in the body (99% found in bone)
  
  • forms matrix w collagen (hydroxyapatite)
• roles in hypertension and weight management
• 1% intra/extracellular components
• • hormones maintain its blood concentration

Question 9

factors affecting absorption of calcium

Answer 9

enhancers: acid, vitamin D

Question 10

stages in life where calcium is absorbed

Answer 10

adults 30%
pregnancy 50%
children 50-60%
peak bone mass occurs during early twenties

Question 11

osteoclast

Answer 11

breaks down bone

with age, clast activity > blast activity

Question 12

nutrients for bone health

Answer 12

calcium
magnesium
vitamin D
phosphorus

Question 13

what is the vitamin D recommendation?

Answer 13

• assume no vitamin D synthesis from the sun

- take 600-800IU or more, no toxicity levels

Question 14

hormones involved in calcium homeostasis

Answer 14

calcitonin, PTH (parathyroid hormone), vitamin D (not a hormone but involved)

Question 15

the role of vitamin D in calcium homeostasis

Answer 15

stimulates calcium reabsorption

Question 16

PTH

Answer 16

parathyroid hormone

• stimulates the activation of vitamin D
• stimulates calcium reabsorption

Question 17

phosphorus

Answer 17

deficiencies are rare

- combines w calcium to make hydroxyapatite, gives bones strength

Question 18

calcitonin

Answer 18

• prevents calcium reabsorption,

- inhibits activation of vitamin D

Question 19

osteomalacia vs osteoporosis

Answer 19

osteomalacia - bones are very soft, and it becomes painful

osteoporosis - bones becomes weak due to loss of bone density

Question 20

vitamin D

Answer 20

deficiency rare, insufficiencies are common

• deficiency can result in rickets in children (bowed legs, growth retardation, etc)
• elderly at risk of deficiency
• • sunlight required to activate vitamin D (5-10 min 3x/wk)

Question 21

what is the DRI for calcium?

Answer 21

1000 mg/day

Question 22

magnesium

Answer 22

half of what’s in our body is found in our bones
linked to lots of enzymes involved in metabolism, muscle contraction
- deficiencies and toxicities rarely occur

Question 23

vitamin K

Answer 23

blood clotting, bone health

deficiencies and toxicities are rare

Question 24

osteoporosis

Answer 24

44% of patients hospitalized w fractures as a result of osteoporosis never return home
- it’s important to accrue lots of bone mass in your early years so that you have more in your later years

Question 25

risk factors for osteoporosis

Answer 25

female gender: menopause and loss of estrogen

older age: less bone density