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DPT 503 > Bone Physiology > Flashcards

Bone Physiology Flashcards

1
Q

organic material

A

collagen and ground substance that give flexibility and resilience to bone

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2
Q

inorganic material

A

calcium and phosphate that make bones stiff

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3
Q

functions of the skeletal system

A

storage: calcium, phosphorus, bone marrow, immune cells (B and T cells), fat, and growth factor

support and protect: the body structures and internal organs

anchorage: muscles and ligaments

hematopoeisis: RBC production in red bone marrow cavity

hormones: osteocalcin from osteoblasts that regulates metabolism and insulin secretion

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4
Q

cortical (compact) bone

A

outer layer of diaphysis

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5
Q

spongy (cancellous, trabecular) bone

A

inside of cortical bone

trabeculae: 3D latticework of thin pieces of bone

benefit: make bones much lighter

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6
Q

epiphysis

A

ends of long bones

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7
Q

diaphysis

A

shaft of long bones

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8
Q

bones are oriented along lines of stress. can these lines of stress change over time?

A

yes, repetition of activity, aging, pregnancy, and growth can change lines of stress

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9
Q

ossification begins in what week of gestation?

A

week 8

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10
Q

endochondral ossification

A

formed by replacing hyaline cartilage and making it bone

forms all bones except skull and clavicles

beings at primary ossification center in the diaphysis where mesenchymal cells specialize into osteoblasts

requires breakdown of hyaline cartilage first

epiphyseal plate: cartilage separating epiphysis and diaphysis (calcified by about 18-21)

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11
Q

intramembranous ossification

A

w/in the membrane

formation of osteocytes

replacing fibrous membranes w/bones

forms skull and clavicles

calcification occurs later (allows easier passage through the birth canal)

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12
Q

where is the primary ossification center?

A

diaphysis (shaft of long bone)

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13
Q

where is the secondary ossification center?

A

epiphysis (ends of long bone)

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14
Q

interstitial growth

A

growth lengthwise

requires epiphyseal plate

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15
Q

appositional growth

A

growth in thickness

bone thickens in response to increases stress (Wolff’s Law)

osteoblasts beneath the periosteum secrete bone matrix

osteoclasts remove bone on the endosteal surface

can occur throughout life

osteoblasts activity>osteoclast activity (bone formation>bone resorption)

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16
Q

epiphyseal plate

A

growth plate

calcified by 18-21 but can go until 25

maintains constant thickness
- cartilage growth on one side is balanced by bones replacement on the other

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17
Q

epiphyseal plate: 5 zones (from epiphyseal side to diaphysis side)

A

resting zone: area on epiphyseal side

proliferation zone: growth zone
- starts mitosis
- new cells pushed away from this zone
- young cartilage cells

hypertrophic zone: cells become bigger

calcification zone: chondrocytes dying
- chondrocytes deteriorate to become bones
- cartilage matrix becomes calcified

ossification zone: calcified cartilage replaced by ossified bone tissues

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18
Q

growth hormone during youth

A

too much=giantism

too little=dwarfism

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19
Q

thyroid hormone during youth

A

increases metabolic rate, insulin regulation, cortisol, heart function, thermoregulation

20
Q

testosterone and estrogen during youth

A

promote growth spurts

end growth by inducing epiphyseal plate closure

21
Q

age related changes in bone

A

children and adolescents:
- osteoblasts>osteoclasts (bone formation>bone resorption)
- higher bone mass in boys

young adults:
- balanced bone formation and resorption

adults (over 40 y/o):
- osteoclasts>osteoblasts (bone resorption>bone formation)
- bone mass, mineralization, and healing abilities decrease w/age
- increased bone loss in white females (can reduce the trend w/exercise)

22
Q

lifelong bone remodeling and repair

A

5-7% bone mass is recycled each week

spongy bone replaced every 3-4 years

cortical bone replaced every 10 years

occurs at surfaces of both periosteum and endosteum

23
Q

osteoclasts

A

bone resorption

24
Q

osteoblasts

A

bone formation

25
Q

hormones

A

determines whether/when remodeling occurs

parathyroid hormone, calcitonin, estrogen, leptin, and serotonin

26
Q

parathyroid hormone

A

responds to low blood calcium and dumps calcium from the bone into the blood.

stimulates osteoclasts to resorb bone

secretion stops when homeostatic calcium levels are reached

27
Q

calcitonin

A

in humans, it has negligible activity but can lower blood calcium temporarily

28
Q

estrogen

A

regulates osteoclasts’ and blasts’ activities

29
Q

leptin

A

released by adipose tissue

regulates appetite

inhibits osteoblasts (less bone formation)

30
Q

serotonin

A

same as leptin

more of a neurotransmitter

inhibits osteoblasts (less bone formation)

31
Q

biomechanical stress

A

weight, growth, body mechanics, etc.

determines where remodeling occurs

32
Q

aging

A

increases osteoclast activity (overall bone loss)

33
Q

nutrition

A

little calcium and vitamin D=weaker bones

34
Q

metabolic and disease processes

A

substance use can lead to brittle bones

osteomalacia

35
Q

lines of force in the body

A

usually no straight lines

compressive force medially, tensive force laterally on the femur
- no force in middle
- thickness greater at mid-shaft where the loads are the greatest

36
Q

Wolff’s Law

A

bones thicken in response to increases stresses

larger bony projection are due to the muscles pulling on them

cortical bone is thickest where bending stress is greatest

application of new forces increases osteoblast activity

reduction of usual forces increases osteoclast activity, resulting in decreased bone mass
- decreased WB/muscle activity=weaker bones bc the bone remodels to adapt to decreased stress

right handed-bones thicker in right arm

37
Q

spurring

A

muscles pulling on bone causes new tuberosity

common in the heel w/plantar fasciitis

38
Q

stress strain curve of cortical bone vs spongy bone

A

cortical bone is stiffer=more vertical curve=less likely to deform upon stress

spongy bone is more compliant=more horizontal curve=more likely to deform upon stress

39
Q

longitudinal loading

A

stiffer

40
Q

transverse loading

A

bone is weaker and won’t be able to w/stand as much force as longitudinal loading

more compliant

41
Q

fast loading

A

bones act stiffer than slow loading

42
Q

stress and strain with large load over short time

A

high stress, low strain

43
Q

stress and strain with low loads over long time

A

low stress, high strain

stress fx

44
Q

response to compression

A

bone withstands greater compression than tension

structure shortens and widens

failure occurs in response to oblique cracking of osteons

45
Q

osteons

A

structural and functional unit of bone that looks like concentric rings

46
Q

response to tension

A

failure occurs in response to de-bonding at cement lines in b/w osteons and pulling out of osteons

avulsion fx

47
Q

influence of muscles on stress distribution in bone

A

muscle contractions alters stress distribution of bone

ski boot injury: overall compressive force from compressive force produced by gastrocs leads to fracture

DPT 503 (22 decks)

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