07a: Bone Histogenesis Flashcards Preview

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Flashcards in 07a: Bone Histogenesis Deck (57)
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1
Q

List the bone cell types. Put a star after the ones that are simply different forms of the same cell.

A
  1. Osteoblast*
  2. Osteocyte*
  3. Osteoprogenitor cell*
  4. Bone lining cell*
  5. Osteoclast
2
Q

Principal cell of bone formation:

A

Osteoblast

3
Q

Osteoblasts can be found on the (X) surface of bone. They function as (independent/interconnected) cells.

A

X = free;

Interconnected

4
Q

(X) are capable of (Y) osteolysis. With this process, they’re managers of (Z).

A
X = osteocytes
Y = osteocytic
Z = bone's Ca reservoir
5
Q

(Osteoblasts/osteocytes) are interconnected via (X).

A

Osteoblasts and osteocytes;

X = gap junctions

6
Q

(X) synthesize the osteoid, aka (Y).

A
X = Osteoblasts
Y = organic material of bone
7
Q

Describe process of (X) transitioning into osteocyte.

A

X = osteoblast;

Changes polarity, secretes matrix on its free surface, and becomes entrapped in lacunae

8
Q

(X) are quiescent osteocytes.

A

X = bone lining cells

9
Q

Osteoprogenitor cells are found in/on:

A
  1. Bone marrow cavity

2. Inner cell layer (cambium) of periosteum

10
Q

Which event(s) would lead to osteocytic osteolysis?

A

Decrease in serum Ca levels

11
Q

The dendrites of (X) reside in (Y), which are filled with (Z).

A
X = Osteocytes
Y = canaliculi
Z = canalicular (tissue) fluid
12
Q

Most, (X)%, of the surface of our bones are covered by:

A

X = 90

Bone lining cells

13
Q

How can (X) bone cells detect pressure changes?

A

X = osteocytes;

Hair-like projections (transducers) extend from dendrites to walls of canaliculi and detect changes in fluid

14
Q

Osteocytes interconnect with:

A
  1. Osteocytes
  2. Osteoblasts
  3. Blood vessels
15
Q

Outer layer of periosteum consists of:

A
  1. Fibroblasts

2. Type I collagen

16
Q

Inner layer of periosteum, aka (X), consists of

A

X = cambium

Osteoprogenitor cells

17
Q

Osteoprogenitor cells are (X)-potent. They can become:

A

X = bi

Fibroblasts or osteoblasts

18
Q

Principal cell of bone resorption:

A

Osteoclast

19
Q

Osteoclast formed by:

A

Asynchronous fusion of monocyte progenitor cells

20
Q

List the membrane domains in osteoclast.

A
  1. Ruffled border
  2. Sealing zone
  3. Basal (anti-resorptive) zone
21
Q

Ruffled border of osteoclast contains:

A
  1. Proton pumps (pump H+ into Howship’s lacuna)

2. Cl channels

22
Q

Sealing zone of osteoclast contains:

A

Rich in actin and integrins (link to bone)

23
Q

Basal zone of osteoclast contains:

A

Cl/HCO3 exchangers

24
Q

Cl is entering osteoclast at (X) and leaving osteoclast at (Y).

A
X = basal zone
Y = ruffled border
25
Q

Which key enzyme in (X) cell allows for bone resorption? What does it (degrade/form)?

A

X = osteoclast

Carbonic anhydrase; produces H+ and HCO3-

26
Q

Which ion(s) are pumped into Howship’s lacuna?

A

H+ and Cl-

27
Q

Mineral component of bone removed by (X). Organic component degraded by (Y).

A
X = acid environment
Y = lysosomal cathepsins, collagenases, metalloproteinases
28
Q

What are the forms of bone histogenesis?

A
  1. Intramembranous

2. Endochondral

29
Q

Intramembranous bone formation is:

A

Direct transformation of condensed mesenchyme

30
Q

What are some characteristics of the (X) tissue in which intramembranous bone formation occurs?

A

X = connective

Primitive, highly vascularized

31
Q

In intramembranous bone formation, (X) cells lay down (Y) in locations equidistant between (Z).

A
X = osteoblasts
Y = osteoid
Z = cappilaries
32
Q

T/F: In intramembranous bone formation, some stem cells are retained.

A

True

33
Q

Primary (X) bone grows (more/less/equally as) rapidly than secondary (Y) bone.

A
X = immature, Woven
Y = mature, Lamellar

More

34
Q

(Woven/lamellar) bone is more cellular.

A

Woven

35
Q

(Woven/lamellar) bone resorbs more slowly.

A

Lamellar

36
Q

(Woven/lamellar) bone has more collagen.

A

Lamellar

37
Q

(Woven/lamellar) bone has more ground substance.

A

Woven

38
Q

(Woven/lamellar) bone mineralizes more rapidly and (more/less) completely.

A

Woven; less

39
Q

Give examples of bone that forms via intramembranous bone formation.

A

Flat bones in head, maxilla, mandible, scapula

40
Q

Endochondral bone formation is:

A

bone formation in cartilage model

41
Q

Give examples of bone that forms via endochondral bone formation.

A

Weight-bearing axial and limb bones

42
Q

List the tasks of chondrocytes in endochondral bone formation.

A
  1. Increase local concentrations of PO4- and Ca
  2. Remove inhibitors of mineralization
  3. Provide means to precipitate and bind mineral
43
Q

Which ion(s) is/are important in endochondral bone formation? Explain.

A

PO4- and Ca; bind matrix vesicles (that bud from chondrocyte membrane) and generate crystals

44
Q

In endochondral bone formation, what’s the source of free crystals that bind to (X) fibers?

A

X = type 10 collagen

Matrix vesicles, with accumulated crystals, break apart and leave crystals in matrix

45
Q

Which fiber type(s) are important in mineralization during endochondral bone formation?

A
  1. Type 10 collagen (binds crystals)

2. Type 2 collagen (bound by Type 10)

46
Q

In endochondral bone formation, the (X) chondrocyte synthesizes:

A
  1. Type 10 collagen
  2. Alkaline phosphatase
  3. Pyrophosphatase
47
Q

In endochondral bone formation, once the blood vessel comes into (cartilage/bone), it brings along:

A

Bone;

  1. Osteoprogenitor cells
  2. Hematopoietic SC
48
Q

Primary ossification center forms in (X).

A

X = diaphysis (central part of long bone)

49
Q

Secondary ossification center forms in (X).

A

X = each epiphysis (end of long bone)

50
Q

T/F: Both ossification centers form pre-natally.

A

False - secondary ossification center forms post-natally

51
Q

Bone fracture healing involves (X) bone formation.

A

X = both endochondral and intramembranous

52
Q

First step of fracture healing:

A

Formation of hematoma (clot)

53
Q

Second step of fracture healing: Once (X) forms, (Y) begin to regenerate and, thus, (Z) become available.

A
X = fibrocartilaginous (soft) callus
Y = blood vessels
Z = osteoblasts (formed from cells of endosteum and periosteum)
54
Q

Why/where is endochondral bone formation necessary in bone fracture repair?

A

Middle of bone (blood vessels take awhile to grow into middle)

55
Q

Third step of fracture healing:

A

Bony (hard) callus forms

56
Q

Final step of fracture healing:

A

Bone remodeling (lamellar bone replaces woven bone)

57
Q

Why is the bony callus (small/large) in diameter?

A

New woven bone lacks strength of lamellar bone, so makes it up by increasing diameter of callus