DSA: Bone Flashcards
(114 cards)
1
Q
What are the 2 major functions of bone?
A
1) Support and protection of the body and its organ 2) A reservoir for calcium and phosphate ions
2
Q
What type of bone is tubular?
A
Long bones
3
Q
What type of bone is cuboidal and found only in the tarsus and carpus?
A
Short bones
4
Q
What type of bone usually serves protective functions?
A
Flat bones
5
Q
What type of bone are the bones of the face?
A
Irregular - Irregular bones are various shapes other than long, short or flat
6
Q
What do sesamoid bones protect tendons from?
A
Excessive wear and other change the angle of the tendons as they pass to their attachments
7
Q
_________ is a layer of specialized CT with osteopenia potential that surrounds most bones
A
Periosteum
8
Q
________ is the marrow wall of the diaphysis and is lined with osteoprogenitor cells
A
Endosteum
9
Q
What are the organic components of bone?
A
Type I collagen Proteoglycans Noncollagenous proteins
10
Q
What are teh 3 main noncollagenous proteins found in bone?
A
Osteocalcin
Osteopontin
Osteonectin
11
Q
What are the inorganic components of bone?
A
Calcium Hydroxyapatite
Magnesium
Potassium
Sodium
Fluoride
12
Q
What classification of bone has an outer solid cortex of bone which encloses an inner layer of spongy bone, and is lamellar?
A
Compact bone
13
Q
What classification of bone has an inner layer of spongy bone with spaces for bone marrow, is lamellar or woven, and contains trabeculae?
A
Spongy
14
Q
Lamellar bone is also known as what classification of bone?
A
Compact
15
Q
Trabecular or cancellous bone is also known as what classification of bone?
A
Spongy
16
Q
________ bone is adult bone, where as _________ bone is immature bone.
A
Lamellar; woven (non-lamellar)
17
Q
________ bone is mechanically strong and forms slowly, whereas ________ bone is mechanically weak and forms rapidly
A
Lamellar; woven
18
Q
Is lamellar bone visible in H&E?
A
No -> dried or ground sections only
19
Q
How are collagen fibers arranged in lamellar bone?
A
Regular parallel arrangement
20
Q
How are collagen fibers arranged in woven bone?
A
Loose arrangement
21
Q
What is woven bone replaced by?
A
Lamellar
22
Q
What is the mineral and cell content like in woven bone?
A
Lower mineral content, more cells
23
Q
What type of bone forms during fracture repair and remodeling?
A
Woven
24
Q
________________ are observed between osteons and separated from them by a thin layer known as the cement line
A
Interstitial lamellae
25
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ are visualized at the external surface of the compact bone under the periosteum
Outer circumferential lamellae
26
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ are seen on the internal surface of lamellar bone subjacent to the endosteum
Inner circumferential lamellae
27
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ is a longitudinal canal that houses capillaries and post capillary venules in the center of the osteon
Haversian canal
28
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ is a transverse or oblique canal connecting Haversian canals with one another, containing blood vessels derived from the bone marrow and some from the periosteum
Volkmann's canal
29
\_\_\_\_\_\_\_\_\_\_ are trapped in the calcified matrix and occupies a lacuna and is responsible for maintenance and turnover of the bone matrix
Osteocytes
30
\_\_\_\_\_\_\_\_\_\_ are pockets in bone that contain osteocytes and are found between lamellae
Lacunae
31
\_\_\_\_\_\_\_\_\_\_\_ connect osteocytes to each other and to the Haversian canal
Canaliculi
32
\_\_\_\_\_\_\_\_\_\_\_ found in bone has a high binding affinity for hydroxyapatite and is a blood biochemical marker of osteogenesis
Osteocalcin
33
\_\_\_\_\_\_\_\_\_\_ found in bone binds to type I collagen and hydroxyapatite
Osteonectin
34
\_\_\_\_\_\_\_\_\_\_ found in bone participates in anchoring of osteoclasts to bone by formation of a sealing zone before resorption
Osteopontin
35
Osteocalcin and osteopontin increase following stimulation with what?
Active vitamin D
36
\_\_\_\_\_\_\_\_\_\_\_\_\_ bones develop when additional ossification centers appear and form extra bones.
Accessory (supernumerary) bones - Many bones develop from several centers of ossification and the separate parts normally fuse. Sometimes one of these centers fails to fuse with the main bone, giving the appearance of an extra bone -\> careful study shows that the apparent extra bone is a missing part of the main bone
37
Circumscribed areas of bone are often seen along the structures of the cranium where the flat bones abut, particularly those related to the parietal bone. These small, irregular, worm-like bones are _________ bones.
Structural bones (wormian bones)
38
It is important to know that accessory bones are common in what structure to avoid mistaking them for bone fragments in radiographs and other medical images?
The foot
39
Bones sometimes form in soft tissues where they are not normally present. Horse riders often develop _____________ bones in their thighs (rider's bones), probably because of chronic muscle strain resulting in small hemorrhagic areas that undergo calcification and eventually ossification.
Heterotropic bones
40
Trauma to a bone may break it. For the fracture to heal properly, the broken ends must be brought together, approximating their normal position. What is this called?
Reduction of a fracture
41
During bone healing, the surrounding ____________ proliferate and secrete collagen which forms a collar of ________ to hold bones together
Fibroblasts; callus - Bone remodeling occurs in the fracture area and the callus calcifies
42
Why are fractures more common in children than adults?
Because of the combination of their slender, growing bones and carefree activities
43
Fractures are more common in children than in adults. Many fractures that occur in children are what type of fracture?
Green stick fractures -\> incomplete breaks caused by bending of the bones \*\*Fractures in growing bones heal faster than those in adults\*
44
During the aging process, the organic and inorganic components of bone both decrease, often resulting in what?
Osteoporosis -\> a reduction in the quantity of bone, or atrophy of skeletal tissue - Bone becomes brittle, loses its elasticity and fracture easily - Bone scanning is an imaging method used to assess normal and diminished bone mass
45
Examination of bone marrow provides valuable information for evaluating what kind of diseases?
Hematological (blood) diseases
46
Because it lies just beneath the skin and is easily accessible, the __________ is a commonly used site for harvesting bone marrow.
Sternum
47
The age of a young person can be determined by studying the ________________ in bones
Ossification centers
48
The fusion of epiphysis with the diaphysis occurs 1-2 years earlier in what gender
Girls
49
How does starvation and illness affect growing bone?
Proliferation of cartilage at the metaphysics slows down but the degeneration of cartilage cells in the columns continues, producing a dense line of provisional calcification -\> these lines later become bone with thickened trabeculae or lens of arrested growth
50
Loss of arterial supply to an epiphysis or other parts of a bone results in avascular necrosis. After every fracture, small areas of adjacent bone undergo necrosis. In some fractures, avascular necrosis of a large fragment of bone may occur. In a number of clinical disorders of epiphyses in children result from avascular necrosis, these disorders are referred to as what?
Osteochondroses
51
Label A-D
A) Interstitial lamellae
B) Outer circumferential
C) Osteon/Haversian system
D) Lacuna
52
Label E-I
53
What type of bone is found where tendons insert, such as teeth sockets?
Woven bone
54
What is characteristic of the inner layer of periosteum?
Preosteoblasts (osteoprogenitor cells)
Osteogenic layer
55
What is characteristic of the outer layer of periosteum?
Rich in blood vessels and nerves
Fibroblasts and collagen fibers
Sharpeys fibers
56
What are sharpeys fibers?
Anchoring collagen fibers that penetrate the outer circumferential lamellae
57
Which layer of the periosteum is highly innervated and is why breaking bones hurts?
Outer layer
58
What part component of bone covers spongy walls, extends into all cavities of bones, and contains osteoprogenitor cells, reticular stromal cells of bone marrow and connective tissue fibers?
Endosteum
59
What do osteoprogenitor cells give rise to?
Osteoblasts
60
What are osteoprogenitor cells?
They are precursor cells that self-replicate, or differentiate into bone-forming cells
61
What are osteoblasts?
Bone-forming cells that deposit osteoid and control subsequent mineralization
62
What are osteocytes?
Modified osteoblasts that become surrounded by newly formed bone
63
What are osteoclasts?
Macrophage-type cells that resorb bone in the remodeling process
64
What do osteoclasts have high levels of?
Acid phosphatase and collagenase
65
Where do osteoclasts come from?
Circulating monocytes
- Will fuse together (multinucleated)
66
When osteoclasts are attached to bone they have a ruffled edge called what?
Howship's lacunae -\> a small resorption bay/pit
67
How are osteoblasts and osteoclasts different based on size?
Osteoclasts are much bigger/multinucleated
68
Where do osteoclasts attach to the bone for resorption?
Howship's lacunae
69
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ is a disorder of bone, characterized by decreased mineralization of newly formed osteoid at sites of bone turnover (bone become soft)
Osteomalacia
\*\*ONLY ADULTS\*\*
70
What 3 things cause osteomalacia?
Dietary vitamin D deficiency
Lack of sun exposure
In the US GI disease
71
Bone and joint pain, muscle weakness, fracture, difficulty walking and waddling gait, and muscle spasms and cramps are all signs and symptoms of what bone related disorder?
Osteomalacia
72
How does GI disease contribute to osteomalacia?
Unable to absorb Ca2+, PO4+ and vitamin D
73
What cells are most affected in osteomalacia and why?
Osteoblasts because this is a problem with mineralizing the bone. You have osteocalcin binding Ca2+ and an osteonectin binding the type I collage in bone as well as Ca2+, both of these protein secreted by osteoblasts. To secrete these proteins you need vitamin D and here you have a deficiency so osteoblasts are most affected
74
What lab values of calcium, phosphorus and alkaline phosphatase would be expected in osteomalacia?
Calcium = decreased or normal
Phosphorus = decreased or normal
Alkaline phsophatase = increased
75
Why would alkaline phosphatase levels be increased in a pt with osteomalacia?
Osteoblasts are trying but cant mineralize bone
76
What would you expect bone to look line on an X-ray of a pt with osteomalacia?
You will see a bunch of pseudofractures, not true fractures. Milkman pseudofractures
77
What would restore the milkman pseudofractures seen in pts with osteomalacia?
Restoring vitamin D
78
In what developmental stage is osteogenesis happening?
In embryo
79
What form of ossification uses a mesenchymal template?
Intramembranous ossification
80
What form of ossification uses a cartilage template?
Endochondral ossification
81
What form of ossification forms the frontal and parietal bones and part of the occipital, temporal, mandible, maxilla and clavical?
Intramembranous ossification
82
Which form of ossification forms the portions of the basicranium, long bones, pelvic and pectoral girdles and ribs?
Endochondral ossification
83
During intramembranous ossification, mesenchyme will differentiate into \_\_\_\_\_\_\_\_\_\_, which will secrete osteoid, as osteoid becomes mineralized it will trap these cells now called ___________ and will start formation of _________ bone
Osteoblasts; osteocytes; woven
84
During intramembraneous bone formation, at the same time osteoid deposition is occuring, the mesenchyme will start to condense to form the __________ and \_\_\_\_\_\_\_. This CT will be forming at the same time
Periosteum and endosteum
85
Toward the end of intramembranous ossification, osteoid is continually laid down forming spongy bone trabeculae that will eventually convert the spongy bone to what?
Compact bone
86
During intramembranous ossification, where do osteocytes become trapped?
within the calcified osteoid
87
What are the 4 main steps of intramembranous ossification?
1) Condensation of mesenchyme into soft sheet permeated with blood capillaries
2) Deposition of osteoid tissue by osteoblasts on mesenchymal surface; entrapent of first osteocytes; formation of periosteum
3) Honeycomb of bony trabeculae formed by continued mineral deposition; creation of spongy bone
4) Surface bone filled in by bone deposition, converting spongy bone to compact bone; persistence of spongy bone in the middle layer
88
What are the 6 main steps of endochondral ossification?
1) Mesenchum devleops into a body of hyaline cartilage covered with a fibrous perichondrium (will grow in thickness)
2) Perichondrium stops producing chondrocytes and starts producing osteoblasts
3) Blood vessels penetrate the bony collar and invade the primary ossification center
4) devleopment of the medullary cavity
5) Chondrocyte enlargement and death create a secondary ossification center in the epiphysis
6) The epipysis will fill with spongy bone
89
Where do chondrocytes begin to die in endochondral ossification?
In the primary ossification center
- This is where they are in the middle and enlarge and die
90
What produces the primary marrow cavity during endochondral ossification?
Blood vessels penetrating the bony collar and invading the primary marrow cavity
91
What cell type forms the thin collar of bone during endochondral ossification?
Osteoblasts
92
During endochondral ossification, after the primary marrow cavity is formed ________ line the cavity and deposit osteoid and form the spongy bone. A wave of cartilage death progresses toward the endof the the bone and __________ follow the wave enlarging the marrow cavity of the diaphysis
Osteobasts; osteoclasts
93
\_\_\_\_\_\_\_\_\_ growth happens at the epiphyseal plates in children. Only _________ growth can occur in adults
Interstitial; appositional
94
During endochondral ossification, cartilage is limited to what?
The epiphyseal plate
95
\_\_\_\_\_\_\_\_ refers to deficient mineralization of cartilage at the growth plate, as well as architectural disruption of this structure
Rickets
96
What type of rickets is caused by calcium deficiency?
Calcipenic rickets
97
What are the 2 things that can cause calcipenic rickets?
- Insufficient intake or metabolism of vitamin D
- INsufficient intake or absorption of calcium in the setting of normal vitamin D levels
98
Delayed closure of the fontanelles, parietal and frontal bossing, craniotabes (soft skul bones), widening of the wrist and bowing of the distal and radius ulna and progressive lateral bowing of the femur and tibia are all signs of what disease?
Rickets
99
What cells would be most affected in rickets and why?
Chondrocytes because chondrocytes arent able to start the initial calcification in the zone of cell hypertrophy so they will be unable to move down into zones 4 and 5
100
What lab values would you expect for calcium, phosphorus and alkaline phosphatase in patients with rickets?
Calcium = decreased or normal
Phosphorus = decreased or normal
Alkaline phosphatase = increased
101
What is the most common skeletal dysplasia causing short-limb dwarfism?
Achondroplasia
102
What type of bones are affected in achondroplasia?
Long bones are affected while the cranial and vertebral bones are spared
103
What is the mutation causing achondroplasia?
FGFR3 (fibroblast growth factor receptor 3) mutation on chromosome 4
\*normally controls as signal that stops chondrogenesis\*
104
How does the FGFR3 mutation lead to dwarfism?
FGFR3 becomes overactive -\> inhibits cartilage synthesis resulting in decreased endochondral bone formation and premature ossification of the growth plates
105
What zone of endochondral ossification is most affected in pts with achondroplasia?
Proliferative zone (zone 1)
- stopped it from starting to stack into the columns
106
What are the 4 steps in the conversion of trabecula into an osteon?
1) ridges in periosteum create groove for periosteal blood vessel
2) Periosteal ridges fuse, forming an endosteum-lined tunnel
3) Osteoblasts in endosteum build new concentric lamellae inward toward center of tunnel, forming new osteon
4) Bone grows outward as osteoblasts in periosteum build new circumferential lamellae. Osteon formation repeats as new periosteal ridges fold over blood vessels
107
Why do we need to form an osteon from trabecula?
to develop lamellar bone so that its stronger, more mature, and more stable
108
What are the 4 general steps of compact bone remodeling within an osteon?
1) activation
2) Resorption
3) Reversal
4) formation
109
What bone disease is characterized by low bone mass, microarchitecture disruption, and skeletal fragility, resulting in decreased bone strength and an increased risk of fracture?
Osteoporosis
110
What populations of individuals does osteoporosis commonly occur in?
Postmenopausal caucasian women and the elderly
111
What are the signs of osteoporosis?
No clinical manifestations occur until there is a fracture
112
What cells would be most affected in an individual with osteoporosis and why?
Osteoclast activity outplaces osteoblast activity
- There is typically a balance between osteoblasts and osteoclasts, but the osteoclast activity is starting to be the primary mechanism, which will be breaking down more bone than is being formed
113
What would the lab values of calcium, phosphorus, and alkaline phosphatase be in an individual with osteoporosis?
All normal!
114
