Histo - Bone Ossification Flashcards
(93 cards)
1
Q
What is ossification?
AKA ____
A
ossification aka osteogenesis
is the development of bone tissue
2
Q
What are the two steps in ossification (aka osteogenesis)
A
- development of primary bone (woven, immature) TEMPORARY
2. primary bone replaced by secondary bone (mature, lamellar) PERMANENT
3
Q
Bone tissue is a type of ___
A
connective tissue
4
Q
Bone tissue arises from connective tissue called ____
A
mesenchyme
5
Q
What are the two types of ossification (osteogenesis)?
A
- intramembraneous ossification
2. endochondrial ossificatino
6
Q
Which type of ossification has a hyaline cartilage model precursor?
A
endochondrial ossifiction
7
Q
Which type of ossification follows this pattern:
mesenchyme -> bone
A
intramembraneous ossification
8
Q
Which type of ossification follows this patterm:
mesenchyme -> hyaline -> hyaline cartilage -> bone
A
endochondrial ossification
9
Q
Intramembraneous ossification leads to the production of which type of bones?
A
flat bones of skull and face
10
Q
Which type of ossification leads to the production of flat bones of the skull and face?
A
intramembraneous ossification
11
Q
Endochondrial ossification leads to the production of which type of bones?
A
short and long bones in the body
12
Q
Which type of ossification leads to the production of short and long bones?
A
endochondrial ossification
13
Q
When do intramembraneous ossification and endochondrial ossification each begin?
A
intramembraneous begins to occur ~8weeks gestation
endochondrial
- first hyaline cartilage visible ~6weeks gestation
- ossification centers are present in all long bones of limbs by 12th week gestation
14
Q
What are the 4 steps of intramembranous ossification?
A
- development of ossification center
- calcification
- woven bone and periosteum develop
- replacement of woven bone
15
Q
In intramembranous ossification, explain what happens histologically as mesenchymal cells differenate?
A
elongated, pale staining mesenchymal cell clusters differentiate into osteoprogenitor cells
they become more rounded
cytoplasm changes from acidophilic to basophilic
16
Q
In intramembranous ossification, why does the cytoplasm change from acidophilic to basophilic as mesenchymal cell clusters differentiate into osteoprogenitor cells?
A
addition of rER
17
Q
In intramembranous ossification, the osteoprogenitor cells differentiate into ____
A
osteoblasts
18
Q
In intramembranous ossification, clusters of ___ create the ossification center.
these cells secrete ____
A
osteoblasts.
osteoblasts secrete organic ECM (osteoid)
19
Q
In intramembranous ossification, what do osteoblasts secrete?
A
organic ecm (osteoid)
20
Q
In intramembranous ossification, describe the calcification step.
A
Calcium and other mineral salts are deposited around the framework of collagen fibers in intramembranous ossification
21
Q
In intramembranous ossification, during calcification, cells trapped in calcified osteoid are now called ____
A
osteoclasts in lacunae
22
Q
In intramembranous ossification, when do osteoclasts form? How?
A
osteoclasts are trapped in the calcified osteoid during the calcification step
(calcification step = when calcium and other mineral salts are deposited around framework of collagen fibers)
23
Q
What is appositional growth?
A
growth along the surface
24
Q
In intramembranous ossification, how is woven bone produced?
A
produced in small, irregularly shaped pieces or spicules that increase in size by appositional growth
25
In intramembranous ossification, describe how appositional growth affects how woven bone is formed?
appositonal growth allows small patches of bone production to merge together to produce a labrynth of woven bone
26
In intramembranous ossification, what are spaces between bone spicules of woven bone filled with?
What does that differentiate into?
embryonic blood vessels
will differentiate into red bone marrow
27
In intramembranous ossification, where do embryonic blood vessels go?
What do they differentiate into?
between the bone spicules of woven bone development
will differentiate into red bone marrow
28
In intramembranous ossification, how does periosteum form?
mesenchyme at periphery of bone condenses to form periosteum
29
In intramembranous ossification, mesenchyme at periphery condenses to form ___
periosteum
30
In intramembranous ossification, what is woven bone replaced with?
lamellar bone
31
What are the 6 stages of endochondrial ossification?
1. Development of fetal cartilage model
2. Bone collar forms and cartilage begins to calcify
3. Primary ossification center forms in diaphysis
4. Secondary ossification center forms in epiphysis
5. Hyaline cartilage retained for articular cartilage & epiphyseal plate
6. Epiphyseal plate ossifies into line
32
In endochondrial ossification, mesenchyme differentiates into ____
chondroblasts
33
In endochondrial ossification, chondroblasts (differentiated from ___) secrete what? produces what?
chondroblasts are differentiated from mesenchyme
They secrete matrix (type II collagen)
Produces hyaline cartilage model
34
In endochondrial ossification, what specifically produces hyaline cartilage?
the chondroblasts (differentiated from mesenchyme) secrete matrix (type II collagen) and PRODUCE HYALINE CARTILAGE MODEL
35
In endochondrial ossification, hyaline cartilage continues to grow via what type of growth?
both appositional and interstitial growth.
interstitial growth because chondrocyte activity in lacunae
appositional growth because of chondroblasts activity at surface
36
In endochondrial ossification, how does hyaline cartilage grow via appositional growth?
chondroblast activity at surface
37
In endochondrial ossification, how does hyaline cartilage grow via interstitial growth?
chondrocyte activity in lacunae
38
In endochondrial ossification, bone collar forms around ___.
diaphysis
39
In endochondrial ossification, while the bone collar is forming around the diaphysis, the cartilage of the ___ begins to calcify
shaft
40
In endochondrial ossification, progenitor cells from what region differentiate into osteoblasts?
progenitor cells from the perichondrium of the midregion of cartilage
differentiate into osteoblasts
41
In endochondrial ossification, progenitor cells from the perichondrium of the midregion of cartilage differentiate into ___
osteoblasts
42
In endochondrial ossification, once progenitor cells from midregion perichondrium differentiate into osteoblasts, what is it called?
periosteum
43
In endochondrial ossification, when is the periochondrium called the periosteum?
once the progenitor cells from the perichondrium from midregion differentiate into osteoblasts
44
In endochondrial ossification, osteoblasts that are produced along the surface of the midregion secrete ___
osteoid which is calcified
creates bone collar around midregion of hylaine cartilage model
45
In endochondrial ossification, how is osteoid secreted?
from osteoblasts that are produced along the surface of the midregion
46
In endochondrial ossification, what specifically creates the bone collar around the midregion of hyaline cartilage model?
the osteoblasts that are produced along the surface of the midregion
47
In endochondrial ossification, the bone collar forms along the ___
diaphyseal portion of the bone
48
In endochondrial ossification, what is the first bone seen in ossification?
the bone collar
49
In endochondrial ossification, bone collar impedes on ____
diffusion of oxygen and other nutrients
50
In endochondrial ossification, what impedes on diffusion of oxygen and nutrients?
bone collar
51
In endochondrial ossification, chondrocytes accumular ___ and undergo ____
glycogen and undergo hypertrophy
52
In endochondrial ossification, what accumulates glycogen and undergoes hypertrophy?
chondrocytes
53
In endochondrial ossification, what produces alkaline phosphatase?
What does this do?
chondrocytes produce alkaline phosphatase
| this makes the matrix calcify
calcified cartilage is not bone
54
In endochondrial ossification, what does alkaline phosphatase do? What is it from?
alkaline phosphatase makes the matrix calcify
it is produced from chondrocytes
55
In endochondrial ossification, what is the difference histologically between calcified cartilage and bone?
calcified cartilage is blue/purple
newly formed bone is pink or red
56
In endochondrial ossification, the calcified matrix means that there is no diffusion, so ____ subsequently die.
chondrocytes
57
In endochondrial ossification, why do the chondrocytes die?
because calcified matrix means no diffusion of oxygen or nutrients to chondrocytes
58
In endochondrial ossification, when chondrocytes die, what does this create?
a porous, 3D structure of cartilage is created in shaft of diaphyseal plate
59
In endochondrial ossification, what creates the primary ossification center?
capillaries and osteoprogenitor cells from new periosteum penetrate bone collar and grow into disintegrated calcified cartilage center
60
In endochondrial ossification, _____ penetrate the bone collar and grow into disintegrating calcified center to create primary ossification center
capillaries and osteoprogenitor cells
61
In endochondrial ossification, capillaries and osteoprogenitor cells penetrate the ____ and grow into _____ to create primary ossification centers
penetrate the bone collar and grow into the disintegrated calcified center
62
In endochondrial ossification, the blood vessels brought into primary ossification centers at core of diaphysis will differentiate into ____
red bone marrow
63
In endochondrial ossification, osteoprogeitor cells brought into primary ossification centers will differentiate into ___
osteoblasts
64
In endochondrial ossification, osteoblasts in primary ossification center begin to deposit ____
bone matrix against remnants of calcified cartilage
65
In endochondrial ossification, where is the primary ossification center found? Where is the remaining hyaline cartilge?
primary ossification center found in diaphysis
remaining hyaline cartilage at epiphyses of developing bone
66
In endochondrial ossification, how secondary ossification centers develop in comparison to primary ossification centers?
very similarly, but secondary ossification centers are in the epiphysis of developing bone
67
In endochondrial ossification, where is the hyaline cartilage retained? for what purpose?
retained at ends of hyaline cartilage model for articular cartilage
this is for the cushioning of the bone ends participating in joints
68
In endochondrial ossification, the remnant of hyaline cartilage between epiphysis and metaphysis is called what?
what is it responsible for?
epiphyseal plate
responsible for lengthwise growth in long bones
69
In endochondrial ossification, the epiphyseal plate is a remnant of what?
Where on a long bone specifically is it located?
hyaline cartilage from the hyaline cartilage model
located between epiphysis and metaphysis
70
In endochondrial ossification, when are secondary ossification centers developed?
shortly after birth
71
In endochondrial ossification, when does the epiphyseal plate turn into the epiphyseal line?
at the end of puberty
| which marks the end of growth in terms of height
72
In endochondrial ossification, what causes the epiphyseal plate to become the epiphyseal line?
changes in hormone at end of puberty cause the cartilage to be replaced with bone
73
In endochondrial ossification, what is the remnant of the last location of the epiphyseal plate?
the epiphyseal line
74
What are the 5 zones of bone growth?
```
1 resting reserve cartilage
2 proliferating cartilage
3 hypertrophic cartilage
4 calcified cartilage
5 ossification
```
75
Describe zone I:
- Name?
- What can we see here?
- What's occurring?
resting reserve cartilage
closest to epiphysis
can see chondrocytes singular or in small groups
no active ECM production, no mitosis underway
76
Describe zone 2:
- Name?
- What can we see?
- What's occurring?
proliferating cartilage
chondrocytes undergo mitosis (stack like coins) on long axis (stacks are called ISOGENOUS GROUPS) actively produce ecm
this pushes epiphysis away from diaphysis to lengthen
77
Which zone of bone growth are isogenous groups found? what do they do?
zone 2: proliferating cartilage
they are stacks of chondrocytes undergoing mitosis and actively producing ECM aka pushing epiphysis away from diaphysis (growing)
78
Zone 3:
- Name?
- What can we see?
- What's occurring?
hypertrophic cartilage
chondrocytes increase in size (hypertrophy) so matrix is compressed/thinned because of cell expansion
cytoplasm if chondrocytes accumulate glycogen
79
Zone 4:
- Name?
- What can we see?
- What's occurring?
Calcified cartilage
(basophilic)
calcified through formation of hydroxyapetite crystals
chondrocytes can no longer recieve nutrients because calcified cartilage... so they die.
80
Zone 5:
- Name?
- What can we see>
- What's occurring?
ossification
next to diaphysis, directly in contact with marrow tissue
blood vessels, osteoprogenitor cells, osteoclasts go into space where chondrocytes were
woven bone is laid down by osteoblasts where cartilage spicules were
primary bone is eroded by osteoclasts to create secondary bone
81
Bone grows width-wise through ___ growth.
appositional
82
At what two surfaces does the bone grow width wise?
periosteal surface and endosteal surface
83
What is the difference between periosteal appositional growth and endosteal appositional growth?
both grow bone width-wise
periosteal surface - osteoblasts secrete bone matrix
endosteal surface - osteoclasts break down bone matrix
84
In terms of bone growing wide, at which surface do osteoblasts secrete matrix? Where do osteclasts breakdown matrix?
osteoblasts at periosteal
osteoclasts at endosteal
85
Why should the rate of osteoblast activity equal the rate of ostaclast activity?
to keep bones from becoming too heavy or thin
86
What are the two controls impacting bone remodeling?
What do they each control? (Where/When)?
Negative feedback loop controls WHEN remodeling occurs
(calcitonin and parathyroid hormone)
Bone's response to mechanical stress and gravity determines WHEN remodeling occurs
87
If too much calcium is in the blood, ___ secrete ____.
parafollicular cells in thyroid gland secrete calcitonin
88
What does calcitonin do?
inhibits osteoclasts
encourages calcium to be deposited in ECM, thus increases osteoblast activity
lowers evevated blood Ca levels by removing Ca from blood to put into bone
89
Where is calcitonin released from?
parafollicular cells in thyroid gland
90
When is calcitonin released?
when there is too much calcium in blood
91
If too little calcium is in the blood, ____ secretes ____
parathyroid gland secrete parathyroid hormone
92
What does parathyroid hormone do?
stimulates osteoclasts to resorb bone
releases Ca from bone storage to enter bone
raises low blood calcium elvels back to normal
93
Where is parathyroid hormone released from?
parathyroid gland
