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KIN 267 > Chapter 6 > Flashcards

Chapter 6 Flashcards

1
Q

(6) important functions of skeletal system:

A
  1. **support **(structural framework) & **point of attachment **for tendons & ligaments
  2. **protect **internal organs
  3. assist **body movement **
  4. **store **& **release **calcium & phosphorus
  5. blood cell production (hematopoiesis)
  6. store **triglycerides **in adipose cells of yellow marrow
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2
Q

Bone is **dynamic tissue **… it is always ___

A

**remodeling **- building up & breaking down

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3
Q

(2) major **bone tissues **

A

1) bone (osseous tissue)
2) cartilage

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4
Q

Bone

A

highly vascularized CT with hard mineralized ECM found in 2 different arrangements

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5
Q

(2) different arrangements of bone

A

1) spongy
2) compact

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6
Q

Compact bone

  • functions
  • forms?
A

protection & support

  • forms **diaphysis **of long bones & **external layer ** of all bones
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7
Q

Spongy Bone

  • functions
  • forms?
A

lightweight

provides tissue support

forms most of epiphysis & internal cavity of long bones

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8
Q

Articular Cartilage

  • location
  • purpose
A

thin layer of hyaline cartilage covering epiphysis of long bones

  • covers part of epiphysis where bone forms joint
  • reduces friction & absorbs shock
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9
Q

Periosteum

A

membrane covering bone surface not covered by articular cartilage

  • attached to bone by Sharpey’s fibers
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10
Q

Periosteum - **purposes (4) **

A

1) protect bone
2) assist in fracture repair
3) nourish bone tissue
4) attachment point for ligaments/tendones

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11
Q

(2) layers of Periosteum

A

1) tough **outer **sheath of dense, irregular CT
2) inner **osteogenic **(bone stem cells) layer

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12
Q

How is **periosteum **attached to the bone?

A

by Sharpey’s Fibers

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13
Q

Medullary Cavity

A

space within diaphysis of long bones that contains **fatty yellow bone marrow **in adults

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14
Q

Endosteum

A

membrane that lines medullary cavity

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15
Q

Various cells in **Osseous tissues **

A

osteogenic cells → osteoblast → osteocyte

osteoclast (WBC)

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16
Q

Osteogenic cells

A

undergo cell division & develop into osteoblasts

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17
Q

Osteoblasts

A

bone building cells

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18
Q

Osteocyte

A

mature bone cells

principal cells of bone tissue

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19
Q

Osteoclasts

A

derived from monocytes & serve to break down bone tissue

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20
Q

Chemical Constituents of Bone

A

25% water

25% organic proteins

50% mineral salts (hydroxyapatite crystals).

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21
Q

**Organic constituents **of bone

  • functions
A

**collagen fibers **

  • provide flexibility & tensile strength
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22
Q

**Inorganic **constituents of bone

A

**Hydroxyapatite crystals (mineral salts) **

  • Calcium Phosphate (Ca3PO4)2
  • Calcium Carbonate (CaCO3 – marble)
  • Other trace elements: Mg, F, sulphate
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23
Q

Bone Structure

A

diaphyses

epiphyses

metaphyses

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24
Q

Diaphysis

A

shaft or body of a long bone

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25
Q

Epiphyses

A

forms distal & proximal ends of a long bone

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26
Q

Metaphyses

A

areas where epiphyses & diaphysis join

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27
Q

Until end of active growth, epiphysis of long bones contains? forms?

A

hyaline cartilage & forms “epiphyseal growth plate”

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28
Q

In adults, epiphyseal cartilage is?

A

** no longer present** & elongation of bones has stopped

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29
Q

Compact Bone (cortical bone)

  • contains?
A

contains units osteons (Haversian systems) formed from concentric lamellae (rings of calcified matrix) arranged around **central canal **

  • interstitial lamellae
  • outer circumferential lamellae
  • inner circumferential lamellae
  • lacunae
  • canaliculi
  • **perforating canals **
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30
Q

**Interstitial **lamellae

A

left over fragments of older osteons between osteons

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31
Q

Outer circumferential lamellae

A

encircle bone beneath periosteum

  • connect to peristeum by **perforating (sharpey’s) fibers **
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32
Q

Inner circumferential lamellae

A

encircle medullary cavity

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33
Q

Lacunae

A

small spaces between lamellae which house osteocytes

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34
Q

Canaliculi

A

small channels filled with extracellular fluid connecting lacunae

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35
Q

Central canal

A

canal in center of osteons

  • blood & lymphatic vessels
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36
Q

Perforating (Volkmann’s) canals

A

allow transit of vessels in Central Canal to outer cortex of bone

  • allows vessels & nerves from periosteum to penetrate compact bone
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37
Q

Spongy bone

A

lacks osteons → lamellae arranged in lattic of thin columns (trabeculae)

make up interior bone tissue & houses red bone marrow

**lacunae **contain osteocytes (nourish mature bone tissue from blood circulating through trabeculae)

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38
Q

Spongy Bone → Trabeculae

A

structural unit of spongy bone

-lamellae arranged in lattice of thin columns

  • contain **lacunae **→ contain osteocytes that nourish bone tissue from blood circulating through trabeculae
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39
Q

Purpose of spongy bone

A

reduces overall weight

support/protect red bone marrow → site of hemopoiesis

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40
Q

Blood & Nerve Supply of Bone → periosteal arteries & veins

A

supply periosteum & compact bone

enter diaphysis through **perforating **(Volkman’s) canals

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41
Q

Blood and Nerve Supply of Bone → **nutrient **artery

A

near center of **diaphysis **

passes through nutrient foramen

enters medullary cavity & divides proximal & distal branches

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42
Q

Blood & Nerve Supply of Bone

A

nerves may accompany blood vessels

  • periosteum is rich in sensory nerves
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43
Q

Bone formation

A

**ossification **or **osteogenesis = **process of formaing new bone

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44
Q

ossification or osteogenesis

  • occurs in (4) situations
A

process of formaing new bone

1) formation of bone in embryo
2) growth of bones until adulthood
3) **remodeling **of bone
4) **repair **of fracture

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45
Q

Osteogenesis

  • occurs by?
  • when does it begin?
A

occurs by 2 different methods

beginning about 6th week of embryonic development

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46
Q

**Osteogenesis **- (2) methods

A

1) **Intra-membranous **ossification
2) **Endochondral **ossification

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47
Q

1) **Intra-membranous **ossification

A

produces spongy bone

  • subsequently**, **be remodeled to form compact bone
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48
Q

2) Endochondral ossification

A

process whereby cartilage is replaced by bone

forms both **compact **& **spongy **bone

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49
Q

Intramembranous Ossification

  • forms?
  • forms from?
A

used in forming flat bones of skull, mandible & clavicle

bone forms from mesenchymal cells -without going through cartilage stage

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50
Q

Intra-membranous Ossification

  • steps (4)
A

1) Development of ossification centre
2) Calcification
3) Formation of trabeculae
4) Development of periosteum

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51
Q

Intra-membranous ossification

1) Development of ossification centre

A

chemical msgs cause mesenchymal cells to cluster (**ossification centre) ** & differentiate into osteogenic cells → osteoblasts - secrete ECM until surrounded

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52
Q

Intramembranous Ossification

2) Calcification

A

secretion of ECM stops

now osteocytes lie in lacunae & extend cytoplasmic processes into canaliculi that radiate in all directions

within few days: calcium & other mineral salts deposited & ECM calcifies (hardens)

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53
Q

Intramembranous Ossification

3) Formation of trabeculae

A

As bone ECM forms, develops into trabeculae that fuse to form spongy bone around network of blood vessels

CT asociated with blood vessels differentiates in red bone marrow

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54
Q

Intramembranous Ossification

4) Development of periosteum

A

In conjunction with formation of trabeculae
mesenchyme condenses into periosteum

eventually, thin layer of compact bone replaces surface spongy bone layers

Much of newly formed bone is remodeled (destroyed and reformed) as bone is transformed into its adult size & shape.

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55
Q

Endochondral Ossification

  • steps (6)
A

1) Development of Cartilage model
2) Growth of Cartilage Model
3) Development of primary ossification centre
4) Development of medullary cavity
5) Development of secondary ossification centre
6) Formation of articular cartilage & epiphyseal (growth) plate

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56
Q

Endochondral Ossification

1) Development of Cartilage model

A

chemical msgs cause mesenchymal cells to crowd into general shape of bone

→ develop into chondroblasts - secrete cartilage ECM → produce cartilage model (hyaline)

  • perichondrium develops around
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57
Q

Endochondral Ossification

2) Growth of Cartilage Model (4)

A

once chondroblasts buried in cartilage ECM → chondrocytes

- interstitial/appositional growth

as model grows, chondrocytes in mid-region hypertrophy (increase in size) & surrounding cartilage ECM calcifies

  • chondrocytes die & spaces left behind merge into small cavities (lacunae)
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58
Q

2a) Interstitial (endogenous) growth

A

grows in length by continual cell division of chondrocytes & further secretions of cartilage ECM

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59
Q

2b) Appositional (exogenous) growth

A

growth in thickness due to deposition of ECM on cartilage model surface by new chondroblasts developed from perichondrium

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60
Q

Endochondral Ossification

3) Development of primary ossification centre (4)

A

primary ossification proceeds inward from external bone surface

  • nutrient artery penetrates perichondrium & calcifying cartilage model through nutrient foramen → stimulates osteogenic cells in perichondrium to differentiate into osteoblasts
  • (once perichondrium starts to form bone - known as periosteum)*
  • near middle of model, periosteal capillaries grow into calcified cartilage & induce growth of primary ossification center (region where bone tissue will replace most of cartilage)

osteoblasts deposit bone ECM over remnants of calcified cartilage → forms trabeculae

  • eventually, most of diaphysis wall replaced by compact bone
61
Q

Endochondral Ossification

4) Development of medullary cavity

A

as primary ossification centre grows towards ends of bone, osteoclasts break down trabeculae leaving medullary cavity in shaft

eventually, most of diaphysis wall replaced by compact bone

62
Q

Endochondral Ossification

5) Development of secondary ossification centre

A

when branches of epiphyseal artery enter epiphyses → secondary ossification centres develop (around time of birth)

bone formation similar to primary oss. centres but:

spongy bone remains in interior of epiphysis (no medullary cavity formed) & secondary ossification proceeds outwards from centre of epiphysis to outer bone surface

63
Q

Endochondral Ossification

6) Formation of articular cartilage & epiphyseal (growth) plate

A

hyaline cartilage that covers epiphyses become articular cartilage

before adulthood, hyaline cartilage remains b/w diaphysis & epiphysis as epiphyseal (growth) plate (region responsible for lengthwise growth of long bones)

64
Q

During infancy, childhood, and adolescence, bones throughout the body grow in thickness by?

and long bones lengthen by?

A

appositional growth

interstitial growth - addition of bone material on the diaphyseal side of epiphyseal plate

65
Q

Growth in Length

  • (2) major events
A

1) Interstitial growth of cartilage on epiphyseal side of epiphyseal plate
2) Replacement of cartilage with bone on diaphyseal side of epiphyseal plate

66
Q

Growth in Length

  • epiphyseal (growth) plate has (4) zones
A

1) Zone of Resting Cartilage
2) Zone of Proliferating Cartilage
3) Zone of Hypertrophic Cartilage
4) Zone of Calcified Cartilage

67
Q

Epiphyseal (growth) plate

1) Zone of Resting Cartilage

A

nearest epiphysis

  • consists of small, scattered chondrocytes
  • do not function in bone growth
  • anchor epiphyseal plate to epiphysis of bone
68
Q

Epiphyseal (growth) plate

2) Zone of Proliferating Cartilage

A

slightly larger chondrocytes arranged like stacks of coins

  • undergo interstitial growth as they divide & secrete ECM

→ divide to replace those that die at diaphyseal side of plate

69
Q

Epiphyseal (growth) plate

3) Zone of Hypertrophic Cartilage

A

consists of large, maturing chondrocytes arranged in columns

70
Q

Epiphyseal (growth) plate

4) Zone of Calcified Cartilage

A

final zone → only few cells thick

  • mostly dead chondrocytes b/c ECM around them is calcified
  • osteoclasts dissolve calcified cartilage
  • osteoblasts & capillaries from diaphysis invade area
  • osteoblasts lay down bone ECM (replacing calcified cartilage by endochondral ossification)
  • becomes new diaphysis firmly cemented to rest of diaphysis of bone
71
Q

Ossification contributing to bone length usually completed by?

A

18-21 years old

72
Q

Even after epiphyseal growth plates have closed, bones still continue to? are capable of?

A

thicken & are capable of repair

73
Q

Only way diaphysis can increase in length?

A

activity of epiphyseal plate

74
Q

Order of Zones in Epiphyseal plate from epiphysis to diaphysis

A

Zone of:

Resting cartilage

Proliferating cartilage

Hypertrophic cartilage

Calcified cartilage

75
Q

Growth in Thickness/Width by appositional growth

A

periosteal cells differentiate into osteblasts → secrete ECM

  • become surrounded → osteocytes
  • forms grooves around periosteal blood vessel → becomes tunnel
  • periosteum becomes endosteum that lines tunnel
  • osteoblasts in endosteum deposit bone ECM forming new concentric lamellae

→ proceeds inward, filling in tunnel

  • as osteon forms, osteoblasts under periosteum deposit new circumferential lamellae (further increasing thickness of bone)
  • osteoclasts of endosteum destroy bone lining forming medullary cavity
76
Q

Human Growth Hormone (HGH)

  • functions (secretion)
A

one of body’s many anabolic hormones

Secretion of HGH stimulates:

  • bone growth
  • muscle growth
  • loss of fat
  • increase glucose output by liver
    *
77
Q

Bone remodeling

  • involves? (2)
A

ongoing replacement of old bone tissue by new bone tissue

involves: bone resorption & bone deposition

78
Q

Bone Remodeling

a) Bone resorption
b) Bone deposition

A

a) removal of minerals & collagen fibers from bone by osteoclasts

(results in destruction of bone ECM)

b) addition of minerals & collagen fibers to bone by osteoblasts

(results in formation of bone ECM)

79
Q

At any given time, __% of total bone mass in body is being remodeled

A

5%

80
Q

renewal rate for compact bone tissue is about ___% per year

A

4%

81
Q

renewal rate for spongy bone tissue is about __% a year

A

20%

82
Q

Benefits of Remodeling
(3)

A

1) since strength of bone is related to degree to which it is stressed, if newly formed bone is subjected to heavy loads, it will grow thicker and therefore be stronger than old bone.
2) shape of a bone can be altered for proper support based on the stress patterns experienced during remodeling process
3) new bone is more resistant to fracture than old bone

83
Q

Bone Growth and Remodeling

  • balance must exist between..
A

actions of osteoclasts & osteoblasts

84
Q

Imbalance between actions of osteoclasts & osteoblasts can result in? (4)

A

1) acromegaly

2) osteoporosis

3) rickets

4) osteomalacia

85
Q

1) acromegaly

A

bone becomes abnormally thick & heavy b/c too much new tissue is formed

86
Q

2) osteoporosis

A

excessive loss of calcium weakens bones - osteoclast activity

87
Q

3) rickets
4) osteomalacia

A

excessive loss of calcium causes bones to be too flexible/soft

88
Q

Factors Affecting Bone Growth and Bone Remodeling

  • normal bone metabolism depends on (3)?
A

adequate dietary intake of:

1) Minerals
2) Vitamins

sufficient levels of:

3) Hormones

89
Q

Factors Affecting Bone Growth and Bone Remodeling:

1) Minerals

A

large amounts of Ca, P

smaller amounts of Mg, F & Mn

  • required for bone growth & remodeling
90
Q

Factors Affecting Bone Growth and Bone Remodeling

2) Vitamins (5)

A

Vitamin A

Vitamin C

Vitamin D

Vitamin K

Vitamin B12

91
Q

Vitamin A

A

stimulates activity of osteoblasts

92
Q

Vitamin C

A

needed for synthesis of collagen

93
Q

Vitamin D

A

promotes absorption of calcium from foods in GI tract into blood

94
Q

Vitamins K & B12

A

needed for synthesis of bone proteins

95
Q

3) Hormones (6)

A

1) HGH
2) insulinlike growth factors (IGFs)
3) estrogen
4) testosterone
5) Parathyroid hormone (PTH)
6) Calcitonin

96
Q

3) Hormones - most important to bone growth in childhood?

A

Human Growth Hormone (HGH - produced by pituitary gland

Growth Factors (IGFs) - produced by liver

97
Q

3) Hormones
- HGH & IGFs both… (3)

A

stimulate osteoblasts

promote cell division at epiphyseal plate

enhance protein synthesis

98
Q

3) Hormones - Thyroid hormones (a) & Insulin (b)

A

promote bone growth
by stimulating osteoblast activity (a) & increasing synthesis of proteins (b)

99
Q

3) Hormones - Sex Hormones (4)

A

At puberty - secretion of estrogen & testosterone

Responsible for:

  • increased osteoblast activity
  • synthesis of bone ECM
  • sudden “growth spurt” that occurs during teen years
  • closing down epiphyseal plates

Estrogen promotes widening of pelvis in females

100
Q

During adulthood, sex hormones contribute to? by?

A

bone remodeling by slowing resorption of old bone & promoting deposition of new bone

  • Estrogen slows resorption by promoting apoptosis (programmed death) of osteoclasts
101
Q

3) Hormones - PTH & calcitonin

A

critical for balancing levels of Ca & P between blood & bone

102
Q

Why does maintaining a normal serum Ca2+ level take precedence over mineralizing bone?

A

too high Ca2+ → cardiac arrest

too low Ca2+ → respiratory arrest (stop breathing)

103
Q

Ca2+ exchange is regulated by hormones, the most important of which is?

A

Parathyroid Hormone (PTH)

104
Q

PTH

  • effect on Ca2+ level
A

increases blood Ca2+ level

operates via negative feedback system

105
Q

Negative Feedback System of PTH

A

stimulus causes decrease in blood Ca2+ level

PT gland cells (receptors) detect change → increase production of cAMP (input)

detected by gene for PTH within nucleus of PT gland cell (control center)

increased PTH synthesis (output) →released into blood

stimulates osteoclasts (effectors) → bone resorption

release of Ca2+ from bone into blood

106
Q

How else does PTH increase Ca2+ level?

A

PTH acts on kidneys (effectors) to decrease Ca2+ loss in urine

PTH stimulates formation of calcitroil (active form of vitamin D) → promotes absorption of calcium from food in GI tract into blood

107
Q

What Hormone works to decrease blood Ca2+ level?

How?

A

Calcitonin (CT)

increase in blood Ca2+ level → parafollicular cells in thyroid gland secrete CT → inhibits osteoclast activity, increase blood Ca2+ uptake by bone & Ca2+ deposition into bone

108
Q

What hormones stimulate osteoclast activity & lower serum calcium level?

A

Calcitonin

HGH & sex hormones (to lesser exent)

109
Q

Calcium Homeostasis

A

high blood Ca2+ level → thyroid gland parafollicular cells release more CT → CT inhibits osteoclasts → decreases Ca2+ level → stimulates parathyroid chief cells to release more PTH

(1) → PTH promotes release of Ca2+ from bone ECM into blood & slows loss of Ca2+ in urine

(2) → PTH stimulates release of calcitriol from kidneys → stimulates increased absorption of Ca2+ from food

→ increases Ca2+ level

110
Q

Fractures
- different criteria for naming (3)

A

1) anatomical appearance
2) disease/mechanism which produced fracture
3) common pattern of injury

111
Q

Fractures named by anatomical appearance (10)

A
  1. Partial
  2. Complete
  3. Closed (simple)
  4. Open (compound)
  5. “Green stick”
  6. Impacted
  7. Comminuted
  8. Spiral
  9. Transverse
  10. Displaced
112
Q

1) Partial

A

incomplete break of bone

113
Q

2) complete

A

fracture all the way through bone

114
Q

3) closed (simple)

A

broken bone does NOT puncture skin

115
Q

4) open (compound)

A

broken ends of bone puncture skin

116
Q

5) Greenstick

A

partial fracture in which one side of bone is broken & other side bends

  • similar to breaking green twig
  • occurs only in children (bones not fully ossified & contain more organic than inorganic material)
117
Q

6) Impacted

A

one end of fracture bone forcefully driven into interior of other

  • distal part shoved up into proximal part
118
Q

7) Comminuted

A

bone is splintered/crushed/broken into pieces at site of impact

119
Q

8) spiral

A

occurs when rotating force applied along axis

120
Q

9) Transverse fracture

A

broken straight across

121
Q

10) displaced fracture

A

both ends of broken bone seperated

122
Q

Fractures classified by disease/mechanism which produced fracture

(3)

A

1) Pathological
2) Compression
3) Stress

123
Q

1) Pathological

A

caused by disease that led to weakness of bone structure

-chronic disease like osteoporosis or cancer weakens bone

124
Q

2) Compression

A

produced by extreme forces such as in trauma

125
Q

3) Stress

A

produced by repeated strenuous activites such as running

- series of microscopic fissures in bone that form without any evidence of injury to other tissues

126
Q

Fractures described by common pattern of injury (2)

A

1) Colles’
2) Pott’s

127
Q

1) Colles’ fracture
- usually occurs by?

A

Fracture of distal end of lateral forearm bone (radius) in which distal fragment is displaced posteriorly

  • commonly caused by falling onto hard surface with outstretched hand
128
Q

2) Pott’s fracture

A

Fracture of distal end of lateral leg bone (fibula), with serious injury of distal tibial articulation

129
Q

Fracture & Repair

  • steps (4)
A

1) Formation of fracture hematoma
2) Fibrocartilaginous callus formation
3) Bony callus formation
4) Bone remodeling

130
Q

Fracture repair:

1) Formation of fracture hematoma

A

blood vessels crossing fracture line broken - in peristeoum & osteons

leaking blood forms mass (usually clotted) around site of fracture → fracture hematoma

  • usually forms 6-8 hours after injury

lack of blood circulation →nearby bone cells die → swelling & inflammation

→ produces additional cellular debris →removed by phagocytes & osteoclasts

131
Q

Fracture Repair

2) Fibrocartilaginous callus formation

A

fibroblasts from periosteum invade fracture side → produce collagen fibers

cells from periosteum develop into chondroblasts → produce fibrocartilage

  • lead to development of fibrocartilaginous (soft) callus (mass of repair tissue consisting of collagen & cartilage that bridges broken ends of bone)
  • takes about 3 weeks (can take up to 6 months)
132
Q

Fracture Repair

3) Bony callus formation

A
  • In areas closer to well‐vascularized healthy bone tissue:* osteogenic cells develop into osteoblasts → produce spongy bone trabeculae

trabeculae joins living & dead portions of original bone fragments

fibrocartilage converted to spongy bone →callus referred to as a bony (hard) callus

  • lasts about 3 to 4 months.
133
Q

Fracture Repair

4) Remodeling

A

dead portions of original broken bone fragments resorbed by osteoclasts

compact bone replaces spongy bone around fracture periphery

  • fracture line disappears but thicken area on surface remains as evidence
134
Q

Bone Tissue & Mechnical stress

A

bone tissue has limited ability to alter strength in response to changes in mechanical stress

  • when stressed, can become stronger through increased mineral salt deposition & production of collagen fibers by osteoblasts
135
Q

Main mechanical stresses on bone (2)

A

pull of skeletal muscles

pull of gravity

136
Q

Unstressed bones

A

become weaker

  • can have dramatic bone loss (up to 1% per week)
137
Q

Aging & Bone Tissue

A

decrease in bone mass occurs as level of sex hormones diminishes during middle age

138
Q

As the level of sex hormones diminishes during middle age… what happens?

  • especially for who?
A

bone resorption (by osteoclasts) outpaces bone deposition (by osteoblasts)

  • especially for womejn after menopause
139
Q

Why does loss of bone mass in old age typically have a greater adverse effect in females?

A

women’s bones generally smaller & less massive to begin with

  • contributes to higher incidence of osteoporosis in females
140
Q

(2) principal effects of aging on bone tissue

A

1) Loss of bone mass
2) Brittleness

141
Q

Effects of Aging:

1) Loss of bone mass

  • results from?
A

Demineralization - loss of calcium & other minerals from bone ECM

  • usually begins after age 30 in females
  • accelerates greatly around age 45 (as estrogen levels decrease)
  • continues until as much as 30% of calcium in bones is lost by age 70
142
Q

Once bone loss begins in females, about ___% of bone mass is lost every 10 years

A

8%

143
Q

For men:

Calcium loss typically does not begin until ___ , and about __% of bone mass is lost every 10 years

A

after age 60

3%

144
Q

Effects of Aging

2) Brittleness
- results from?

A

decreased rate of protein synthesis

  • organic part of bone ECM (mainly collagen fibers) gives bone its tensile strength
  • loss of tensile strength causes bone to become brittle & susceptible to fracture
  • collagen fiber synthesis slows partly due to diminished HGH production*
145
Q

Osteoporosis

  • often due to? (2)
A

condition where bone resorption outpaces bone deposition

  • often due to depletion of calcium from body OR inadequate intake
146
Q

Estrogen & Osteoporosis

- both sexes

A

Estrogen maintains density in both sexes (inhibits resorption)

Men: testes & adrenal glands produce estrogen

Women: rapid loss after menopause if:

  • body fat too low

OR

  • with disuse during immobilization
147
Q

Osteoporosis

- Treatment

A

Estrogen Replacement Therapy (ERT)

  • slows bone resorption but increases risk of breast cancer, stroke & heart disease

Best Treatment = prevention - exercise & calcium intake (1000-1300 mg/day) between ages 9 and 71+

  • milk = ~300 mg/250 ml
  • Vitamin D - ~600 IU per day*

40** IU/100 ml milk **by law

148
Q

Bone difference in late adulthood of:

1) retired athlete
2) control

A

1) 2 hypotheses

  • # 1 → larger circumference but thinner (FALSE)
  • # 2 → larger circumference & thicker (TRUE)

2) smaller circumference & thinner

149
Q
A

KIN 267 (12 decks)

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