CH 6 - Skeletal System Flashcards

1
Q

What are the components of the skeletal system?

A

Bones, cartilages, joints, connective tissues

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2
Q

Osteology

A

The study of bone structure and treatment of bone disorders

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3
Q

What are the functions of the skeletal system?

A

Support

Store minerals and lipids

Blood cell production

Protection

Leverage

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4
Q

Hematopoiesis (hemopoiesis)

A

Process of producing blood cells

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5
Q

What are examples of long bones?

A
Phalanges
Metacarpals
Metatarsals
Femur
Tibia
Fibula
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6
Q

What are examples of irregular bones?

A
Vertebrae
Pelvic bones
Sacrum
Sphenoid
Ethmoid
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7
Q

What are examples of flat bones?

A

Ribs
Scapula
Cranial bones
Sternum

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8
Q

What are examples of short bones?

A

Talus
Carpals
Tarsals

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9
Q

Diaphysis

A

The shaft of a long bone, made of compact bone

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10
Q

Medullary cavity

A

Central space within a long bone that contains yellow bone marrow

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11
Q

Epiphysis

A

The wide ends of a long bone that articulates with other bones, made of spongy bone

*May contain red or yellow bone marrow

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12
Q

Cortical bone (cortex)

A

A layer of compact bone that surrounds spongy bone

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13
Q

Epiphseal growth plate

A

Residual hyaline cartilage allowing the bones to grow longer

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14
Q

Epiphyseal line

A

The ossified bone tissue product once the epiphyseal growth plate is done growing

*Adult height is reached

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15
Q

Describe the structure of a flat bone.

A

Spongy bone between two layers of cortical bone

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16
Q

Diploë

A

Spongy bone layer within the cranium

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17
Q

Osseous tissue

A

A type of supporting connective tissue that contains specialized cells, ground substance, and extracellular protein fibers that form the matrix of bone tissue

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18
Q

What is the organic matrix of bone comprised of?

A

Collagen fibers and bone cells

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19
Q

What does the organic matrix of bone do?

A

Provide strength & flexibility

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20
Q

What is the inorganic matrix of bone comprised of?

A

Calcium salts

  • calcium phosphate
  • calcium hydroxide
  • calcium carbonate

Minerals

  • sodium
  • magnesium
  • fluoride
  • phosphorus
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21
Q

What does the inorganic matrix of bone do?

A

Provide rigidity & compression strength

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22
Q

What are osteocytes?

A

Amitotic, mature bone cells within a lacuna

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23
Q

What are the functions of osteocytes?

A

Maintain protein/mineral content of bone matrix

Participate in repairs of damaged bone

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24
Q

Canaliculus

A

Gap junctions that provide osteocytes with nutrients and oxygen

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25
Q

What do osteoblasts do?

A

Produce & release proteins/organic components of the organic bone matrix

Promote calcification to produce new bone

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26
Q

What is osteogenesis (bone deposition) and what are the 2 steps involved?

A

Process of forming bone

  1. Ossification
  2. Mineralization
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27
Q

Ossification

A

Replacing tissue with bone

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28
Q

Calcification

A

Accumulation of calcium salts in the organic matrix

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29
Q

Mineralization

A

The addition of calcium and other minerals to osteoid

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30
Q

What are osteoprogenitor (osteogenic) cells?

A

Connective tissue stem cells that arise from mesenchymal cells

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31
Q

What do osteoprogenitor (osteogenic) cells do?

Where are they found?

A

Produce & maintain population of osteoblasts

Cell (osteogenic) layer of periosteum, endosteum

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32
Q

What are osteoclasts?

A

Giant cells with 50+ nuclei, derived from stem cells that produce leukocytes

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33
Q

What do osteoclasts do?

A

Osteolysis/bone resorption

Secretes acids to dissolve calcium salts, and collagenase to dissolve collagen fibers, in order to destroy/erode bone

*Releases stores minerals into blood

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34
Q

Why do osteoclasts have ruffled borders?

A

To increase their surface area

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35
Q

Osteon (haversian system)

A

The basic unit of bone

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36
Q

Central canal (Haversian canal)

A

Hollow tube in the middle of the osteon that contains an artery, a vein, and a nerve

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37
Q

Perforating canals (volkmann’s canals)

A

Hollow tubes running perpendicular to the central canal that carry blood vessels and nerves into bone

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38
Q

Concentric lamallae

A

Thin layers of bone matrix produced by osteoblasts around the central canals of compact bone

*Osteocytes are arranged in concentric lamellae which forms the osteon

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39
Q

Circumferential lamellae

A

Layers of bone matrix found at the external and internal bone surfaces that enclose the osteons and is covered by the periosteum or endosteum

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40
Q

Interstitial lamellae

A

Remnants of recycled osteons that fills in the spaces between existing osteons

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41
Q

Trabeculae

A

A meshwork of supporting thin columns (bony struts) that are covered by the endosteum

*Grows and adapts throughout life

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42
Q

Describe the structure of spongy bone.

A

Trabeculae allows for stress in many directions.

Spaces between trabeculae are filled with red or yellow bone marrow.

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43
Q

Periosteum

A

An external membrane that covers all external bone surfaces except parts enclosed in joint capsules or articular cartilage

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44
Q

What are the 2 layers of the periosteum?

A

Outer, fibrous layer

Inner, cellular layer (osteogenic layer)
*No osteocytes, but all others

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45
Q

Perforating fibers

A

Thick bundles of collagen fibers of the periosteum that secure it to underlying bone

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46
Q

What are the functions of the periosteum?

A

Isolate bone from urrounding tissue

Provide entrance for blood vessels & nerves

Participates in bone growth/repair/remodeling

Attachment point for tendons/ligaments

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47
Q

Endosteum

A

An internal membrane composed of a single layer of endosteal cells

48
Q

Endosteal cells

A

Osteoblasts, osteoprogenitors, and osteoclasts

*No osteocytes

49
Q

Where is the edosteum?

A

Lining of medullary cavity

Lining of inner surface of central canals/perforating canals

Covers trabeculae of spongy bone

50
Q

What is the function of the endosteum?

A

Participates in bone growth, repair, and remodeling

51
Q

What are the 4 types of bone formation?

A

Initial bone formation of a fetus

Pre-adult bone growth

Bone remodeling

Repair of fractures

52
Q

When does bone begin to develop in a fetus? When is it complete?

A

Bony skeleton begins forming 6 weeks after fertilization

Fetal skeleton is complete after 3 months but is made primarily of cartilage

53
Q

What are the 2 forms of ossification?

A

Intramembranous ossification &

Endochondral ossification

54
Q

Intramembranous ossification

A

Bones form directly within mesenchyme

  • Occurs in flat bones of the cranium
  • Starting tissue: dense fibrous connective tissue
55
Q

Endochondral ossification

A

Bone forms within hyaline cartilage

  • Occurs in all bones
  • Starting tissue: hyaline cartilage
56
Q

Describe the steps of intramembranous ossification.

A
  1. Ossification center develops, osteoblasts secrete organic ECM
  2. Calcification of ECM with added calcium salts/minerals
  3. ECM > trabeculae > spongy bone
  4. Periosteum develops from mesenchyme
57
Q

Describe the steps of endochondral ossification. 🙃

A
  1. Insterstitial (length) & appositional (width) growth of cartilage
  2. Chondroblasts produce a cartilage model surrounded partially by perichondrium
  3. Perichondrium of diaphysis becomes periosteum, bone collar produced, cartilage calcifies
  4. Ossification center forms, blood vessels/osteoblasts invade cartilage, osteoblasts lay down bone matrix, spongy bone forms
  5. Step 4 continues, epiphyses/medullary cavity form
  6. Secondary ossification centers form in epiphyses
  7. Unossified cartilage becomes epiphyseal plate and articular cartilage
  8. Epiphyseal plate becomes epiphyseal line, bone fully formed
58
Q

Interstitial growth

A

Increase in the length of bones (longitudinal or vertical) at the epiphyseal growth plate

59
Q

What are the 5 zones of interstitial growth?

A
  1. Zone of resting cartilage
    • non dividing chondrocytes
  2. Zone of proliferating cartilage
    • chondrocytes actively divide
  3. Zone of hypertrophic cartilage
    • chondrocytes hypertrophy
  4. Zone of calcified cartilage
    • calcified cartilage forms
    • chondrocytes die & leave open space
  5. Zone of ossification
    • osteoblasts fill open spaces
    • osteogenesis begins

*Zone 5 will be closest to medullary cavity and zone 1 will be closest to articular cartilage of each epiphysis

60
Q

Appositional growth

A

An increase in the diameter and thickness of bone

61
Q

What are the steps of appositional growth?

A
  1. Osteoblasts beneath periosteum lay down bone in ridges to form grooves for blood vessels
  2. Groove is transformed to a tunnel when bone of adjacent ridges meet, periosteum of groove becomes endosteum of tunnel
  3. Appositional growth by osteoblasts from endosteum forms new concentric lamellae
  4. Additional concentric lamellae fills tunnel and forms osteon
62
Q

Osteolysis (bone resorption)

A

Removal of minerals and collagen fibers by osteoclasts

63
Q

Bone remodeling

A

Bone resorption & bone deposition

  • Must balance or will end up with over/undergrowth
  • Life-long process
  • No osteoprogenitor cells, but all others
  • Appositional growth
64
Q

Calcitriol

A

The active form of vitamin D3

*Helps absorb calcium and phosphorus from the digestive tract

65
Q

What does vitamin C do for bones?

A

Collagen synthesis

Stimulation of osteoblasts differentiation

66
Q

What do calcium and phosphorus do for bones?

A

Harden bone ECM

67
Q

What do growth hormone, thyroxine, estrogens and androgens do for bones?

A

Stimulate osteoblasts

68
Q

What do calcitonin and parathyroid hormone do for bones?

A

Regulate calcium and phosphate levels

69
Q

What is the normal range of blood calcium?

A

8mg/dL - 11mg/dL

70
Q

Hypercalcemia

A

A blood calcium content above 11mg/dL

71
Q

Hypocalcemia

A

A blood calcium content below 8mg/dL

72
Q

What are the functions of calcium?

A

Bone development/maintenance

Nerve impulse transmission

Muscle contraction

Blood clotting

73
Q

What is calcium homeostasis maintained by?

A

Calcitonin and parathyroid hormone control the storage, absorption, and excretion of calcium

74
Q

How does parathyroid hormone increase blood calcium ion levels? Where does this happen?

A
  1. Stimulate osteoclasts
  2. Increase intestinal absorption of calcium
  3. Decrease calcium excretion from kidneys
  4. Increase calcitriol secretion by kidneys

Parathyroid glands

75
Q

How does calcitonin decrease blood calcium ion levels? Where does this happen?

A
  1. Inhibit osteoclasts activity
  2. Decrease intestinal absorption of calcium
  3. Increase calcium excretion by kidneys
  4. Decrease calcitriol secretions by kidneys

Thyroid gland

76
Q

What is a fracture?

A

A crack or break in bone

77
Q

What are the 4 steps of the bone repair process?

A
  1. Fracture hematoma
  2. Fibrocartilaginous callus
  3. Bony callus
  4. Remodeling
78
Q

Describe a fracture hematoma.

A

A mass of clotted blood (from broken blood vessels within the bone) that forms within 6-8 hours

79
Q

Describe a fibrocartilaginous callus.

A

A fibrocartilage callus fills the space between the ends of broken bone for 3 weeks and tissue repair begins

*Cartilage is present due to avasularity from broken blood vessels

80
Q

Describe a bony callus.

A

Osteoblasts produce trabeculae of spongy bone, and fibrocartilage callus is converted to a bony callus joining the broken bones

*3-4 months

81
Q

Describe bone remodeling.

A

Osteoblasts build compact bone to form the bone collar, then osteoclasts absorb the spongy bone to create a medullary cavity

82
Q

What is an avulsion fracture?

A

Complete severing of a body part

83
Q

What is a colles fracture?

A

Fracture at the distal end of the radius

84
Q

What is a comminuted fracture?

A

Bone is splintered into several small pieces between the main parts

85
Q

What is a complete fracture?

A

Bone is broken into two or more pieces

86
Q

What is a compound (open) fracture?

A

Broken ends of the bone protrude through the skin

87
Q

What is a compression fracture?

A

Bone is squashed

88
Q

What is a depressed fracture?

A

Broken part of the bone forms a concavity

89
Q

What is a displaced fracture?

A

Fractured bone parts are out of anatomic alignment

90
Q

What is an epiphyseal fracture?

A

Epiphysis is separated from the diaphysis at the epiphyseal plate

91
Q

What is a greenstick fracture?

A

Partial fracture where one side of the bone breaks while the other is bent

92
Q

What is a hairline fracture?

A

Fine crack in which sections of bone remain aligned

93
Q

What is an impacted fracture?

A

One fragment of bone is firmly driven into the other

94
Q

What is an incomplete fracture?

A

Partial fracture extends only partway across the bone

95
Q

What is a linear fracture?

A

Fracture is parallel to the long axis of the bone

96
Q

What is a nondisplaced fracture?

A

Bone fragments retain their anatomic position

97
Q

What is an oblique fracture?

A

Diagonal fracture at an angle

98
Q

What is a pathologic fracture?

A

Weakening of a bone caused by disease or infection

99
Q

What is a pott fracture?

A

Fracture is at distal ends of the tibia and fibula

100
Q

What is a simple (closed) fracture?

A

Bone does not break through the skin

101
Q

What is a spiral fracture?

A

Fracture spirals around axis of long bone due to twisting stress

102
Q

What is a stress fracture?

A

Thin fractures due to repeated/stressful impact

103
Q

What is a transverse fracture?

A

Fracture is at right angles to long axis of bone

104
Q

Osteopenia

A

A condition that occurs when the body undergoes more more resorption that deposition

  • Bones become thinner/weaker with age, beginning at 30-40 years
  • Women lose 8% of bone mass per decade, men 3%
105
Q

Osteoporosis

A

Significant reduction of bone mass that compromises normal function

106
Q

Bone mineral density (BMD)

A

The total amount of bone mass in a defined area

  • For a specific bone, total amount of mineral content (calcified bone tissue) measured in grams per centimeter squared
  • High BMD means strong bone
107
Q

Dual energy x-ray absorptiometry (DEXA)

A

A DEXA scanner passes 2 x-ray beams through the body to determine BMD

  • Can measure 1% changes in BMD
  • Focuses on hip joint and vertebrae
108
Q

Fibrodysplasia ossificans progressiva (FOP)

A

A rare genetic disease that replaces muscle tissue with bone

109
Q

Gigantism

A

A condition caused by overproduction of growth hormones BEFORE the closure of the epiphyseal plate

110
Q

Acromegaly

A

A condition caused by the overproduction of growth hormones AFTER the closure of the epiphyseal plate in which bones become abnormally thick

111
Q

Osteitis deformans (paget disease)

A

A chronic disorder that results in enlarged/weak/deformed bones due to excessive bone resorption & regrowth

112
Q

Achondroplasia

A

A genetic disorder of bone growth causing cartilage to be abnormally converted to bone

*Epiphyseal growth plate prematurely ossifies preventing the bones from lengthening

113
Q

Osteogenesis imperfecta (brittle bone disease)

A

Genetic disorder of bone characterized by extreme fragility of bones due to a defect in collagen deposition

*Babies can be born with bone fractures

114
Q

Osteosarcoma (osteogenic sarcoma)

A

A type of cancer that starts in bone

115
Q

Rickets

A

A disease that affects the bones of children/adolescents caused by the failure of the osteoid to calcify, resulting in soft/weak bones from extreme vitamin D deficiency

116
Q

Osteomalacia

A

Adult version of rickets

117
Q

Osteomyelitis

A

A bone infection usually caused by Staph. bacteria

*Can begin from an open fracture, infection after surgery, or infection of another body part that has spread to bone