Lecture 3 Bone Flashcards Preview

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Flashcards in Lecture 3 Bone Deck (167)
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1
Q

What is another name for bone tissue?

A

osseous tissue

2
Q

What type of connective tissue has cells, vessels, nerves, and a matrix hardened by minerals (mostly calcium phosphate)?

A

bone tissue

3
Q

What are the units of the skeletal system?

A

bones

4
Q

What makes up individual bones?

A

bone tissue, marrow, periosteum, endosteum, and cartilage

5
Q

What are the functions of the skeletal system? Hint: (S.P.M.B.H. - Sarah Pulls Mary Behind Her)

A

support, protection of other tissues, movement, blood formation, homeostasis of calcium, phosphate, and pH

6
Q

What type of bones provide leverage for movement?

A

long bones

7
Q

What type of bones can move in several directions?

A

short bone

8
Q

What type of bones protect soft organs and/or provide a broad surface for attachment of powerful muscles?

A

flat bones

9
Q

What type of bones can serve multiple, complex functions?

A

irregular bones

10
Q

What is the name of the tightly adhered, vascular membrane that cover bones (except at articular surfaces)?

A

periosteum

11
Q

What is the name of the enlarged end of a long bone and is covered with articular hyaline cartilage?

A

epiphysis

12
Q

What is the outer layer of bone called?

A

compact bone

13
Q

What are long bones filled with?

A

spongy bone and marrow

14
Q

What is the membrane lining the marrow cavity and all internal passages called?

A

endosteum

15
Q

What is also known as the shaft of the bone?

A

diaphysis

16
Q

What is the cylinder of compact bone containing the marrow cavity (medullary cavity) called?

A

diaphysis

17
Q

What is the diaphysis covered with?

A

periosteum

18
Q

What is another name for the meduallary cavity?

A

marrow cavity

19
Q

What cavity contains hematopoeitic bone marrow tissue in young individuals that is progressively replaced by adipose with age?

A

medullary (marrow) cavity

20
Q

What is the medullary (marrow) cavity lined with?

A

endosteum

21
Q

What are the spongy bone covered with a layer of compact bone and hyaline cartilage called? They are also the enlarged ends of the bone

A

epiphyses

22
Q

What is the purpose of enlarged ends of long bones?

A

to strengthen joints and provide attachments for tendons and ligaments

23
Q

What is covered with articular cartilage of smooth, low friction hyaline cartilage that is lubricated with synovial fluid?

A

joint surface

24
Q

What is the layer of vascular, innervated, dense irregular connective tissue attached to the outer non-articular surfaces of bone called?

A

periosteum

25
Q

What is the name of the layer that is continuous with periosteum that is the internal membranes of bone?

A

endosteum

26
Q

What surrounds nutrient arteries and lines the medullary cavity?

A

endosteum

27
Q

What are the type I collagen fibers that connect the periosteum to the bone matrix?

A

Sharpey’s fibers

28
Q

T/F

Spongy bone has no fiber direction.

A

False.

Pattern is present and fiber direction adds structural integrity to the bone.

29
Q

What is the basic structural unit of bone?

A

Osteon (aka Haversian system)

30
Q

What lines the Haversian Canal?

A

Endosteum

31
Q

What structures connect osteocytes?

A

Pseudopods (within canaliculi)

32
Q

What’s another name for Perforating Canals?

A

Volkman’s canals

33
Q

Are circumferential lamellae part of an osteon?

A

No.

They ring the outside of a bone (diaphysis)

34
Q

What structure branches of compact bone to form spongy bone?

A

Trabeculae

35
Q

What connects periosteum to compact bone?

A

Sharpey’s fibers

36
Q

Inner circumferential lamellae are found between _____ and ______ .

A

Spongy bone

Osteons

37
Q

What is the functional unit of the bone?

A

Osteon (Haversian System)

38
Q

Would you ever see an osteocyte in a ground bone preparation?

A

No.

Lacunae only.

39
Q

What is the name of the blood vessels that penetrate into bones called?

A

nutrient arteries

40
Q

What is the name of the blood vessels that carry blood and fluid out of the bone?

A

periosteal veins and lymphatics

41
Q

What are the remnants of old osteons that fill the spaces between new osteons?

A

Interstitial lamellae

42
Q

What are the external and internal surfaces of flat bone composed of?

A

compact bone

43
Q

What is the middle layer of spongy bone called?

A

diploe

44
Q

Which layer of spongy bone can absorb some of the force of a skull fracture providing some additional protection to the underlying brain?

A

diploe

45
Q

What layer covers the outer surface under the scalp?

A

periosteum

46
Q

What are two other names for spongy bone?

A

Trabecular

Cancellous

47
Q

What type of cells are in the endosteum and periosteum membranes?

A

osteogenic cells

48
Q

What type of cells arise form embryonic mesenchymal cells and become the only source of new osteoblasts?

A

osteogenic cells

49
Q

What type of cells multiply continuously and differentiate into osteoblasts in response to growth, stress, or healing of fractures?

A

osteogenic cells

50
Q

What type of cells produce an extracellular matrix of collagen (mostly type I) and minerals (mostly calcium phosphate)?

A

osteoblasts

51
Q

What type of cells are fully differentiate osteoblasts that are completely surrounded by the matrix they produced?

A

osteocytes

52
Q

What are small, thin, isolated, pieces of bone, as in the development of bone or as in a fragment of bone?

A

spicules

53
Q

What completely surrounds the osteocytes?

A

bone matrix

54
Q

What are the pits in the matrix occupied by the cells?

A

lacunae

55
Q

What is the function of osteoclasts?

A

Resorb and remodel bone.

56
Q

What are the different types of pseudopods?

A

filopodia, cytoplasmic extensions, dendritic processes

57
Q

What are the tiny canals in the bone matrix that contain the filopods?

A

canaliculi

58
Q

What type of cells are arranged in rings in the bone matrix around a central canal that contains blood vessels and nerves?

A

osteocytes

59
Q

What type of junction interconnects the tips of pseudopods of adjacent osteocytes?

A

gap junctions

60
Q

What type of cells use the gap junctions to communicate and to nourish each other?

A

osteocytes

61
Q

Endochondral ossification replaces what connective tissue?

A

Hyaline cartilage

62
Q

What does organic matter of bone matrix consist of?

A

type I collagen, proteoglycans, noncollagenous proteins

63
Q

What are proteoglycans rich in?

A

chondroitin sulfate, keratin sulfate, and hyaluronic acid

64
Q

What are the different types of noncollagenous proteins?

A

osteocalcin, osteopontin, and bone sialoprotein

65
Q

T/F

Only matrix can be seen in a ground section.

A

True

66
Q

What is the difference between an osteocyte and a lacunae?

A

Osteocytes are cells

Lacunae is the matrix surrounding osteocytes.

67
Q

What are the remnants of old osteons that fill the spaces between new osteons?

A

Interstitial lamellae

68
Q

Which noncollagenous protein has a high bonding affinity for hydroxyapatite and is required for bone mineralization?

A

osteocalcin

69
Q

What regulates the expression of osteocalcin?

A

Vitamin D3

70
Q

Which noncollagenous protein regulates the formation and remodeling of mineralized tissues and mediates the formation of the osteoclast sealing zone?

A

osteopontin

71
Q

Which noncollagenous protein mediates binding of osteoblasts to the extracellular matrix through integrins?

A

bone sialoprotein

72
Q

What does inorganic matter of bone matrix consist of?

A

85% hydroxyapatite, 10% calcium carbonate, 5% other minerals

73
Q

What are the crystals that are distributed along collagen fibers and organized by osteocalcin?

A

hydroxyapatite

74
Q

What two materials make bones both strong and resilient?

A

minerals and collagen

75
Q

Which material of bone resist compression?

A

minerals

76
Q

Which material of bone adds resilience?

A

collagen

77
Q

Which type of bone does not have any hollow spaces in the bone matrix?

A

compact bone

78
Q

What type of bone forms the thick-walled tube of the shaft (or diaphysis) of long bones, which surrounds the marrow cavity (medullary cavity)?

A

compact bone

79
Q

What are the other names for spongy bone?

A

cancellous bone and trabecular bone

80
Q

What type of bone consists of a delicate network of trabeculae which branch and intersect to form a sponge-like tissue?

A

spongy bone

81
Q

What type of bone are the ends of long bones filled with?

A

spongy bone

82
Q

What can be seen in a decalcified slide of compact bone?

A

Osteocytes, connective tissue, and vasculature.

83
Q

In compact bone, what canals house neurovascular bundles?

A

Volkman’s Canals and

Haversian Canals

84
Q

What encases osteocyte filopods?

A

Canaliculi

85
Q

T/F

The newest matrix in bone is found furthest from the Haversian Canal.

A

False.

New growth is found in the middle.

86
Q

What are two other names for spongy bone?

A

Trabecular

Cancellous

87
Q

Name the zones of cartilage endochondral ossification from diaphysis to epiphysis.

A

bone deposition, calcification, hypertrophy, proliferation, reserve cartilage

88
Q

In metaphysis, what is the zone where macrophages remove dead chondrocytes and calcified cartilage matrix creating voids that are filled with growing blood vessels surrounded by connective tissue that contains fibroblast-like cells that differentiate into osteoblasts.

A

zone of bone deposition

89
Q

In metaphysis, what is the zone of resting hyaline cartilage called?

A

zone of reserve cartilage

90
Q

In metaphysis, what is the zone of that has a layer of chondrocytes that multiply forming columns of flattened lacunae?

A

zone of cell proliferation

91
Q

In metaphysis, what is the zone that has a region of swollen chondrocytes?

A

zone of hypertrophy

92
Q

In metaphysis, what is the zone where the cartilage matrix calcifies and the chondrocytes die?

A

zone of calcification

93
Q

In metaphysis, what is the zone where macrophages remove dead chondrocytes and calcified cartilage matrix creating voids that are filled with growing blood vessels surrounded by connective tissue that contains fibroblast-like cells that differentiate into osteoblasts.

A

zone of bone deposition

94
Q

What fills spaces between trabecular in spongy bone?

A

Marrow and adipose tissue

95
Q

Name 3 types of bone marrow.

A

Red, Yellow, gelatinous

96
Q

Which bone marrow is hematopoietic?

A

Red

97
Q

Why are many elderly people anemic?

A

The replacement of hematopoietic tissues (red marrow) with yellow and gelatinous marrows.

98
Q

What do megakaryocytes produce?

Where are they found?

A

platelets

Red Marrow

99
Q

What are the two types of ossification processes?

A

Intramembranous

Endochondral

100
Q

What respective tissues are replaced in Intramembranous and Endochondral ossification?

A

Intramembranous replaces Embryonic CT

Endochondral replaces Hyaline Cartilage

101
Q

What bones go through Intramembranous ossification?

A

Mostly flat bones

skull, clavicle, mandible body

102
Q

What is the function of osteoclasts?

A

Resorb and remodel bone.

103
Q

What is the first step in intramembranous ossification?

A

Condensation of mesenchyme

104
Q

What does matrix replace?

A

Osteoid

105
Q

When does an osteoblast become an osteocyte?

A

When it is surrounded by matrix.

106
Q

Osteoclasts are syncicia of ________.

A

macrophages

(and multinucleated)

107
Q

The soft regions of irregular CT present in the skull at birth are called…

A

Fontanels

108
Q

Endochondral ossification replaces what connective tissue?

A

Hyaline cartilage

109
Q

What initiates endochondral ossification?

A

vasculature invades and stimulates chondrocytes in hyaline cartilage

110
Q

How is the primary marrow space formed in endochondral ossification?

A

chondrocytes lay down matrix (suffocating themselves) and it is removed by macrophage.
(space then filled with osteoblasts)

111
Q

What seeds osteoblasts in endochondral ossification?

A

fibroblasts connected to invading membranes

112
Q

In a longbone, where are the primary and secondary ossification centers?

A

Primary - diaphysis

Secondary - epiphysis

113
Q

When does secondary ossification centers begin to form in the epiphyses of long bones?

A

near the time of birth

114
Q

T/F Bone development proceeds all the way to the end of the bone.

A

False; Hyaline cartilage remains over the epiphysis as the articular cartilage of the joint surface

115
Q

What is the transitional zone that is at the junction of the diaphysis and epiphysis and forms an epiphyseal plate?

A

metaphysis

116
Q

What is the cartilaginous tissue between the primary and secondary ossification centers?

A

metaphysis

117
Q

What is the cartilaginous tissue that remains between the medullary cavity (marrow cavity) and the spongy bone in the epiphyses until bone growth ends?

A

epiphyseal plate

118
Q

T/F Bones grow and remodel throughout life.

A

True

119
Q

What type of growth increases the length of bones at the epiphyseal plate?

A

interstitial growth

120
Q

What type of growth increases the width of bones produced by new osteons?

A

appositional growth

121
Q

Why do girls grow faster?

A

Estrogen

122
Q

Growth hormone causes…

A

Bone elongation

123
Q

thyroid hormone increases metabolic rate of…

A

Osteoblasts

124
Q

Name two functions of Calcitonin

A

Deposits Calcium into bone

Inhibits Osteoclasts

125
Q

What stimulates osteoclast growth and increases blood Ca+ levels?

A

PTH

126
Q

Glucocorticoids are increased by…

A

Stress

cause bone loss / impair growth

127
Q

What gland secretes GH (growth hormone)

A

Anterior Pituitary

128
Q

Why are multiple samples necessary to determine GH levels?

A

Pulsatile Secretion

129
Q

Thickening of hand, foot, jaw, and brow bones throughout life is called…

A

Acromegaly (hormone disorder)

130
Q

How many types of dwarfism are there?

A

Over 200

131
Q

What type of dwarfism is characterized by normal sized head and short longbones?

A

Achondroplastic dwarfism

132
Q

What is pituitary dwarfism characterized by?

A

Normal proportions

133
Q

What is primordial dwarfism?

A

growth proportional but severely delayed

134
Q

What are the four types of bone cells?

A

osteoprogenitor, osteoblasts, osteocytes, and osteoclasts

135
Q

What cell secretes osteocalcin and what does it do?

A

Osteoblasts

Directs hydroxyapatite and forms mineralized matrix

136
Q

What binds osteoblast to the matrix through itegrins?

A

Sialoprotein

137
Q

What are the two main components of bone and how do osteoclasts break them down?

A

Matrix - HCl

Collagan fibrils - Acid Phosphatase (released by lysosomes)

138
Q

________ are stimulated by increased pressure and ________ are stimulated by decreased pressure.

A

OsteoClasts

OsteoBlasts

139
Q

What seals the Osteoclast plasma membrane to the mineralized surface of the bone?

A

The “ruffled border”

140
Q

What is the eroded cavity created by osteoclasts called?

A

Howship’s lacuna

also called “resorption bays”

141
Q

Why is the osteoclast considered a “polarized” cell?

A

The ruffled end is much different than the smooth end.

142
Q

What is an important component of the sealing zone in an osteoclast?

A

Osteopontin - binds to an integrin

143
Q

What is the pH of the acidic environment eroding matrix at the ruffled end of an Osteoclast?

A

4.5

144
Q

What follows the cutting zone of osteoclasts in compact bone remodeling?

A

Blood vessel medially and osteoprogenitor cells cortically

145
Q

Osteoblasts fill in the space behind the osteoclast cutting zone with what material?

A

Osteoid (organic bone matrix)

146
Q

What happens to the organic components of matrix after degradation by osteoclaststs?

A

Packaged into endocytotic vesicles and either used by the osteoclast or exocytosed.

147
Q

What induction surface molecule on osteoblasts bind to preosteoclast to initiate differentiation into osteoclast.

A

RANKL

148
Q

What receptor binds RANKL on preosteoclasts?

A

RANK

149
Q

What is a ligand?

A

a binding protein

150
Q

Does PTH stimulate OsteoBlasts?

A

this is a stupid trick question.
Yes, it stimulates osteoblasts to release M-CSF ligand, which binds macrophage, which ends up producing osteoclast, which resorbs bone.

151
Q

How does the drug denosumab work?

A

Interrupts communication between RANK and RANKL

152
Q

What is paradoxical about giving some patients low and intermittent doses of PTH?

A

It can INCREASE osteoblast activity in some patients

mechanism unknown - 2nd messenger system apparently complex

153
Q

What can low calcium levels (hypocalcemia) lead to?

A

muscle excitability, spasms, tremors, tetany

this increases membrane excitability

154
Q

What can high calcium levels (hypercalcemia) lead to?

A

Depresses nervous system activity

this decreases membrane excitability

155
Q

What is Calcitriol?

A

Activated Vitamin D

156
Q

What is the pathway that leads to activated Vitamin D?

A

UV acts on 7-dehydrocholesterol > cholecalciferol > calcidiol (liver) > calcitriol (kidney)

157
Q

What are 3 actions of calcitriol?

A

Stimulates intestines to absorb calcium and phosphate
Promotes urinary resorption of Ca+
Promotes osteoclast activity

158
Q

Where is Calcitonin produced?

A

By C cells in the thyroid

remember ultimobranchial body

159
Q

What does calcitonin do?

A

Reduce osteoclast activity
Increase osteoblast activity
(TONES down CALcium)

160
Q

T/F

Calcitonin has equal effects in children and adults.

A

False

Powerful effect in children not seen in adults

161
Q

How does PTH mobilize Calcium from bone?

A

Stimulates osteoblasts to release osteoclast stimulating factor that promotes osteoclast multiplication and activity

162
Q

Why does PTH inhibit collagen synthesis?

A

It takes a lot of calcium to make collagen, and the point of PTH is to free up calcium and increase its levels in the bloodstream.

163
Q

What class of drug is given as treatment for osteoporosis?

A

Bisphosphonates

164
Q

How do bisphosphonates work, and what bone does it protect?

A

Binds hydroxyapatite sites necessary for osteoclast attachment. This protects old bone.

165
Q

What is the progression of bone fracture healing?

A

Hematoma > Soft Callus > Hard Callus > Remodeling

166
Q

How long does it take to heal a bone fracture?

A

8-12 weeks

167
Q

What is the disease that causes excessive bone production that entombs the body in bone?

A

Fibrodysplasia Ossificans Progressiva