Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MSK Final Exam > L1 - Bone > Flashcards

L1 - Bone Flashcards

1
Q

Describe how bones are organs comprised on many tissues

A

Nerves innervate the periosteum and bone
Blood vessels run in canals within bone
Cartilage covers articular surface
Connected to muscles via tendons and to other bones via ligaments
Houses bone marrow cavities containing blood forming cells and fat cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Describe bone as a CT

A

Strong and fracture resistant
Comprised of cells surrounding or embedded in a mineralized EXM
Impregnated with inorganic material but it is a living and dynamic tissue
Formed from mesenchymal SCs
Well vascularized

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the function of bone (as organs)?

A

Provides a structural framework for the body (support), acts as levers for skeletal muscles (movement), protection of underlying organs, reservoir for minerals including 99% of the body’s Ca and blood cell formation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are osteoprogenitors?

A

Mesenchymal stem cells that produce osteoblasts

Found in periosteum and endosteum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What do osteoblasts from from and where are they found?

A

Mesenchymal stem cells and are only found on the bone surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the function of osteoblasts?

A

Produce bone matrix/osteoid

Initiate and control mineralization of osteoid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the organic component of bone matrix?

A

Type I collagen and proteoglycans

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the inorganic component of bone matrix?

A

Ca phosphate and hydroxyapatite crystals (mineral salts) lying between fibers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the different fates for an osteoblast?

A

Become an osteocyte embedded in bone
Become a bone lining cell (flat resting cell on the surface)
Or die by apoptosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are osteocytes?

A

Mature osteoblasts trapped in bone matrix
Located in lacuna
Have spider like long processes that extend in canaliculi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the purpose of the processes found on osteocytes?

A

Allow them to communicate with other cells by gap junctions

Receive nutrient flow via canaliculi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the functions of osteocyte cells?

A

Communicate with osteoblasts to increase deposition of bone matrix
Maintain bone health (mechanosensory cells and control activity of osteoblasts as well as osteoclasts)
Maintain bone matrix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are osteoclasts differentiated from?

A

Fusion of monocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe osteoclasts

A

Multinucleated cell located on bone surfaces
Create Howship’s lacunae
Important endocrine target for regulating Ca levels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the function of osteoclasts?

A

Remove bone tissue (bone resorption) by degrading the matrix by secreting acids and proteases
Exhibit a ruffled border which resorbs bone through H+ and lysosomal proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is an epiphysis?

A

Knobby regions at ends of bone
Compact bone is superficial with trabecular bone deep to the surface
Contains epiphyseal plate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is a diaphysis?

A

Elongated shaft of long bone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is a metaphysis?

A

Between the diaphysis and epiphysis of long bone
Adjacent to growth plate
Consists of spongy bone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is a the epiphyseal line?

A

Within the metaphysis

Hyaline cartilage within children and adults

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is a medullary (marrow) cavity?

A

Cylinders also space in the diaphysis containing bone marrow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is periosteum?

A

Dense irregular CT covering the external surface of bone
Does not cover articular cartilage
Neurovascular
Anchored by perforating fibers embedded in the bone matrix
Contains osteoblasts and osteoblast precursors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is endosteum?

A

CT lining of all trabeculae and marrow cavity

Contains osteoprogenitor cells, reticular fibers of bone marrow and CT fibers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is an osteon?

A

A cylindrical layered structure comprising of mature compact bone
Runs parallel to the diaphysis
Consists of concentric lamellae (bone matrix surrounding a central canal)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Describe an osteon

A

Has a central canal containing BVs and nerves providing osteocytes with a source of nutrition and O2
Osteocytes are arranged in concentric layers (concentric lamellae) surrounding the vessels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What are lacunae?

A

Where osteocytes reside within an osteon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What are canaliculi?

A

Channels for osteocyte processes and reach to the central blood vessel of the osteon
Interconnected by gap junctions with those of other osteocytes

27
Q

What is the cement line?

A

Outer boundary of the osteon

28
Q

What are circumferential lamellae?

A

Line entire inner and outer circumference of the diaphysis

29
Q

What are interstitial lamellae?

A

Remnants of previous concentric lamellae

30
Q

What are the two major types of bone?

A

Cortical (compact)

Trabecular (spongy or cancellous)

31
Q

Describe cortical (compact) bone

A

Forms outer walls of bone
Primary structures: lamellar (layers) either as circumferential arrangement (osteon) or partial rings (interstitial lamellae)

32
Q

Describe trabecular (cancellous or spongy) bone

A

Forms a network of bony plates or rods
No osteons
Proximal and distal ends of long bones
Can be woven or lamellar bone arrangement

33
Q

What are the two types of bone arrangement?

A

Woven or lamellar

34
Q

What is woven bone?

A

Immature or primary bone
Quickly laid down bone made of irregular and random arrangements of cells and loose collagen with lower mineral content and higher cell density
Usually first bone formed in response to fracture repair

35
Q

Where is woven bone found?

A

In alveolar sockets and where tendons insert into bone

36
Q

Describe lamellar bone

A

Mature
Laid down in highly organized layers with higher mineral content
Replaces woven bone during remodeling and in maintaining compact bone

37
Q

What are the two types of ossification that can occur?

A

Intramembranous and endochondral

38
Q

Describe intramembranous ossification

A

Osteoblasts differentiate directly from mesenchyme and begin secreting osteoid
No cartilage involvement

39
Q

Which bones form via intramembranous ossification?

A

Flat bones of the skull (calvaria), most facial bones and mandible, central part of the clavicle

40
Q

What is endochondral ossification?

A

Develops initially on a hyaline cartilage model
All bones except some bones of the skull and central clavicles
Complete in early childhood
Responsible for lengthening bones

41
Q

Describe the process of endochondral ossification

A
  1. Bone collar forms around the diaphysis of the hyaline cartilage model
  2. Cartilage in the center of the diaphysis calcifies and then develops cavities
  3. The periosteal bud invades the internal cavities and spongy bone begins to form
  4. The diaphysis elongates and a medullary cavity forms as ossification continues
  5. Secondary ossification centers appear in the epiphysis
  6. The epiphyses ossify
42
Q

What occurs in both intramembranous and endochondral bone formation?

A

Woven bone is formed first and then replaced by lamellar bone

43
Q

What is appositional growth?

A

Only way to law down bone
Osteoblasts lay down a layer of bone matrix on top of another layer
Initial bone that is formed is woven which then matures into lamellar

44
Q

Describe bone growth in diameter

A

Growth in circumference of long bones occurs via osteoblasts in the periosteum
Begins with formation of the bone collar on the cartilaginous diaphysis
Accompanied by enlargement of the marrow cavity by activity of osteoclasts in the endosteum

45
Q

What is the purpose of bone remodeling?

A

Repair of micro damage

Ca metabolism: 500mg of Ca may enter or leave the adult skeleton each day

46
Q

What is coupled activity?

A

Resorption by osteoclasts is followed by formation by osteoblasts
Resorption must be linked to formation in order to maintain bone

47
Q

Describe remodeling in trabecular bone

A

Replaced every 3-4 years

Osteoclasts remove bone matrix and then signal osteoblasts to come in and deposit fresh new bone

48
Q

Describe remodeling of compact bone

A

Replaced every 10 years
Osteoclasts tunnel through old bone forming a remodeling tunnel and signal for BVs to follow
Along with BVs osteoblast precursors (osteoprogenitors) flow
Osteoblasts begin depositing concentric rings of lamellar bone at the back end of the tunnel until the tunnel is filled back in leaving a central BV
Thus a new osteon is formed

49
Q

Describe bone fracture repair

A

Torn blood vessels within fracture release blood -> clots and produces fracture hematoma
Hematoma removed by macrophages —> replaced by fibrocartilage like mass, soft callus
If the periosteum is torn, periosteum re-established continuity over soft callus
Procallus invaded by blood vessels and osteoblasts
Fibrocartilage is gradually replaced by woven bone —> forms hard callus
Woven bone is remodeled as compact and cancellous bone
Vasculature is re-established

50
Q

What is the epiphyseal growth plate?

A

Hyaline cartilage found between the primary and secondary ossification centers
Damage to this plate during growth will disrupt lengthening of bone

51
Q

What is the zone of proliferation?

A

Chondrocytes within this plate undergo mitosis and increase cell numbers forming stacks of chondrocytes

52
Q

What is the zone of hypertrophy?

A

Chondrocytes deposit ECM spreading them apart from one another while they also increase in size (interstitial growth)
These cells produce factors that initiate vascular invasion of the cartilage which pushes the epiphysis away from the diaphysis thereby lengthening the bone

53
Q

What is the zone of calcification?

A

Cartilage cells then calcify the surrounding matrix and die

54
Q

What is the zone of ossification?

A

Invading blood vessels bring in osteoprogenitor cells that differentiate into osteoblasts and cover hardened cartilage with woven bone matrix

55
Q

What is the correct order of zones at the epiphyseal plate?

A
  1. Zone of proliferation
  2. Hypertrophic zone
  3. Calcification zone
  4. Ossification zone
56
Q

What is achondroplasia?

A

Autosomal dominant mutation in FGFR3 which is an important mediator of chondroblast proliferation
Most common form of dwarfism
Shortening of long bones, small mid face (defects in cranial base) and altered spinal curvature

57
Q

What is osteoporosis?

A

Characterized by low bone mass due to resorption occurring faster than bone deposition
Occurs most often in women after menopause primarily due to estrogen loss but also in the elderly
Strong genetic component

58
Q

What is estrogen replacement therapy for prevention of osteoporosis after menopause controversial?

A

Due to associated increased risks of heart attack, strokes and cancer

59
Q

What is vitamin D required for?

A

Ca absorption

Deficiency leads to osteomalacia and rickets

60
Q

What is osteomalacia?

A

Occurs in adults

Bones are inadequately mineralized and bones are soft

61
Q

What is rickets?

A

Occurs in children - analogous to osteomalacia but is more severe
Weakened long bones, abnormal head and rib cage

62
Q

What is an osteoclast’s fate?

A

Eventual cell death by apoptosis

63
Q

What do active osteoblasts become?

A

Cuboidal mononuclear cells

MSK Final Exam (26 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions