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

Bone Phys Flashcards

1
Q

An osteon is asst. with what type of bone?

A

Compact/cortical bone

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2
Q

Trabeculae are asst. with what type of bone?

A

Spongey/cancellous bone

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3
Q

What is the composition of bone?

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

What is the organic matter of the bone?

A

Bone cells, collagen fibers, blood vessels and nerves

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5
Q

What is the inorganic matter of the bone?

A

Ca++ and PO4 salts –> Hydroxyapatite crystals

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6
Q

What is the bony matrix of the bone?

A

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

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7
Q

What is an osteoprogenitor cell?

A 
Osteoprogenitor cells (type of stem cell)
periosteum, endosteum and epiphyseal plates osteoblasts
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8
Q

What is an osteocyte?

A

mature bone cells maintaining bony matrix

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9
Q

What is an osteoblast?

A

bone-building cells

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10
Q

What is an osteoclast

A

bone-destroying cells (phagocytic lineage)

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11
Q

What are the functions of the bones?

A
  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
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12
Q

Define tensile strength

A 
Tensile strength (collagen fibers)
strength to endure stretching forces
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13
Q

Define Compressional strength

A 
Compressional strength (calcium salts)
strength to endure squeezing forces
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14
Q

Define Bone remodeling

A
  1. Lifelong process
    A. Bone resorption and new bone formation (ossification)
    B. Micro-damage to bones during nl activity
  2. Following fractures
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15
Q

What are bone turnover markers?

A
  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
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16
Q

Why is bone remodeling a dynamic process?

A

Bone resorption (osteoclasts) and bone formation (osteoblasts)

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17
Q

What is hyaline cartilage?

A
  1. Most abundant, 80% is H2O w/in gel structure

2. Articular cartilage

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18
Q

What is fibrocartilage?

A

Intervertebral disks, areas of tendons connected to bone, menisci

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19
Q

Where is a primary ossification center?

A

Diaphysis

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20
Q

Where is a secondary ossification center?

A

Epiphysis

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21
Q

Define diaphysis

A

Central area of the bone

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22
Q

Define epiphysis

A

Ends of the bone

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23
Q

What system regulates bone physiology?

A

Endocrine system maintains plasma and bone calcium and phosphate balance:

24
Q

What hormones are involved in maintaining bones?

A

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

Phys: Bone & Gen Med: Ortho (14 decks)

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