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Phys: Bone & Gen Med: Ortho > Bone Phys > Flashcards

Flashcards in Bone Phys Deck (56):
1

An osteon is asst. with what type of bone?

Compact/cortical bone

2

Trabeculae are asst. with what type of bone?

Spongey/cancellous bone

3

What is the composition of bone?

1. Mineral matrix of calcium and phosphate salts
2. Collagen fibers and water
3. Organic matter
4. Inorganic matter
5. Bony matrix

4

What is the organic matter of the bone?

Bone cells, collagen fibers, blood vessels and nerves

5

What is the inorganic matter of the bone?

Ca++ and PO4 salts --> Hydroxyapatite crystals

6

What is the bony matrix of the bone?

Dense cortical tissue w/ inner elastic trabecular tissue w/in marrow spaces

7

What is an osteoprogenitor cell?

Osteoprogenitor cells (type of stem cell)
periosteum, endosteum and epiphyseal plates osteoblasts

8

What is an osteocyte?

mature bone cells maintaining bony matrix

9

What is an osteoblast?

bone-building cells

10

What is an osteoclast

bone-destroying cells (phagocytic lineage)

11

What are the functions of the bones?

1. Provide rigidity, hardness, strength & support for body
2. Protects vital internal organs
3. Stores lead and other heavy metals*
A. Released later for excretion
4. Stores minerals calcium & phosphorus
Role in calcium balance

12

Define tensile strength

Tensile strength (collagen fibers)
strength to endure stretching forces

13

Define Compressional strength

Compressional strength (calcium salts)
strength to endure squeezing forces

14

Define Bone remodeling

1. Lifelong process
A. Bone resorption and new bone formation (ossification)
B. Micro-damage to bones during nl activity
2. Following fractures

15

What are bone turnover markers?

1. serum and urine
A. Nl process of bone resorption results in release of bone mineral and osteoid (unmineralized bone, which is composed of collagen

16

Why is bone remodeling a dynamic process?

Bone resorption (osteoclasts) and bone formation (osteoblasts)

17

What is hyaline cartilage?

1. Most abundant, 80% is H2O w/in gel structure
2. Articular cartilage

18

What is fibrocartilage?

Intervertebral disks, areas of tendons connected to bone, menisci

19

Where is a primary ossification center?

Diaphysis

20

Where is a secondary ossification center?

Epiphysis

21

Define diaphysis

Central area of the bone

22

Define epiphysis

Ends of the bone

23

What system regulates bone physiology?

Endocrine system maintains plasma and bone calcium and phosphate balance:

24

What hormones are involved in maintaining bones?

Parathyroid hormone (PTH)*
Calcitriol (1,25- (OH)2 vitamin D3)**: most active metabolite of VD
Calcitonin

25

How is estrogen related to bone density?

Estrogen supports normal bone metabolism by stimulating osteoblastic activity and limiting osteoclastic activity

26

What is PTH secretion regulated by?

PTH secretion follows negative feedback regulation
 Ca++ stimulates PTH release

27

Where is 99% of the body's calcium located?

Bones

28

How does the parathyroid gland maintain bone density?

1. When serum Ca++ , PTH is secreted by chief cells of gland
A. inc Bone Resorption
stimulates osteoclast activity to release stored Ca++ ions and PO4
B. Inc Intestinal absorption of Ca++ by enhancing the action of calcitriol
C. inc Ca++ reabsorption and dec PO4 reabsorption @ kidneys

29

How does the thyroid gland maintain bone density?

1. When serum Ca++ inc, calcitonin is released from parafollicular (or C) cells of gland
2. dec Bone Resorption (inhibits osteoclast activity)
3. No effect on intestines
4. inc excretion of Ca++

30

Describe VD3

Cholecalciferol

31

Describe VD2

Ergocalciferol

32

True/faslse: vitamin D is not a vitamin

True: steroid hormone

33

How much of calcium is active/free?

½ of circulating calcium is bound to albumin
Free, ionized calcium is physiologically active

34

What are the sources of vitamin D?

1. Skin production (d3) from UVB/A rays (90%)
2. jejunal absorption (D2 and D3) 10%

35

What is the role of calcitonin?

1. Calcitonin inhibits D3 production by the kidney
2. Inhibit bone resorption

36

How is inactive D3 metabolized to active D3?

Inactive form D3 --> liver 25 (OH)D3 --> Kidneys -->1,25(OH)2D3

37

What is the active form of Vitamin D3?

1,25(OH)2D3 = calcitriol

38

What are the sxs of hypocalcemia?

1. Paresthesias
A. Perioral, hands, feet
2. muscle cramps or spasms
3. bradycardia
4. lightheadedness

39

What is Chvostek's sign?

Tap over the facial nerve
Positive: twitch

40

What is Trousseau's sign?

Carpal pedal spasm when BP cuff is on and inflated above systolic bp

41

What are the sxs of hypercalcemia?

1. Kidney stones
2. Bone pain, osteoporosis
3. GI upset
A. N/V
B. PUD
4. “thrones”- polyuria and constipation
5. CNS effects
A. Lethargy, fatigue, depression, psychosis, delirium, coma

42

What is the Mnemonic: for hypercalcemia?

“Stones, bones, abdominal groans, thrones and psychiatric moans”

43

What is the cause of hypercalcemia?

Cause of hypercalcemia is primary hyperparathyroidism caused by parathyroid adenoma

44

Define osteopenia/osteoporosis

1. Low bone mass/ Very low bone mass
2. Osteoclast activity > osteoblast activity
A. Weak bones
B> inc risk of fractures

45

When is peak bone mass?

Peak bone mass 25-29 yo, plateaus, then decreases perimenopausally (in men, age 60?)

46

What can osteopenia/osteoporosis be caused by?

hyperparathyroidism

47

Define osteomalacia

1. “Softening of bones”
2. Weak and flexible bones d/t defective mineralization of bones

48

What are the 2 main causes of osteomalacia?

1. Insufficient Ca++ absorption from intestines d/t lack of dietary Ca++ or a deficiency of or resistance to vitamin D
2. PO4 deficiency caused by inc renal losses or dec intestinal absorption
3. Can result from kidney failure or hyperparathyroidism also

49

What is metabolic rickets?

Metabolic bone disorder d/t defective mineralization of growing bones in children --> permanent bone deformities

50

What is nutritional rickets?

inadequate exposure to sunlight and/or inadequate intake of vitamin D, calcium or phosphate

51

What can nutritional rickets be caused by?

1. Underdeveloped countries
2. Prolonged breast-feeding w/o vit D supplementation
3. Soy or rice beverages not fortified w/ vit D

52

What are the physical signs of rickets?

Femurs bend laterally and affected person has bowlegged appearance (genu varum)

53

What are the daily requirements of vitamin D?

Vitamin D3 800-1,000 IU Daily

54

What are the calcium carbonate/citrate daily requirements?

A. >50 yo 1,200 mg
B. 19-50 yo 1,000 mg
C. 9-13 yo 1,300 mg
D. 4-8 yo 800 mg
E. 1-3 yo 500 mg
Where can calcium carbonate be found? Tums

55

Why does kidney failure lead to osteomalacia?

Inactive VD3 cannot be converted into active VD3, increased risk of fracture

56

How much calcium can a person absorb at one time?

500-600 mg