Bone Flashcards
1
Q
What is cartilage surrounded by?
A
A membrane called the pericondrium
2
Q
What causes the strength in cartilage?
A
Collagen fibres
3
Q
What causes the resilience in cartilage?
A
Chondroitin sulfate
4
Q
What is cartilage nourished by?
A
Diffusion of gases and nutrients
5
Q
Are lymphatic vessels or blood vessels present in cartilage?
A
No
6
Q
What does cartilage consist of?
A
- Cells
- Fibers
- Matrix
7
Q
What type of cells are present in cartilage?
A
Chondrocytes
8
Q
Where do cells occur in cartilage?
A
Within spaces in the matrix called lacunae
9
Q
What do fibres consist of?
A
A dense network of collagen and/or elastin fibres
10
Q
What is the matrix in cartilage composed of?
A
- Proteoglycans
- Ground substance
11
Q
What is it called when a structure has no blood vessels?
A
Avascular
12
Q
Where is the only place where blood vessels/nerves are present in cartilage?
A
Perichondrium
13
Q
What is the function of mesenchymal cells in bone?
A
Differentiate into chondroblasts
14
Q
What is the function of chondroblasts?
A
Synthesise ground & substance & matrix (cartilage)
15
Q
What are chondrocytes embedded in?
A
In matrix
16
Q
What type of cells are chondrocytes
A
Mature cells
17
Q
What is the term for the formation of cartilage?
A
Chondrification
18
Q
NB!! What are the 5 steps in the formation of cartilage?
A
- Mesenchymal cells differentiate chondroblast
- Chondroblasts proliferate & synthesise ground substance & fibrous extracellular matrix
- Chondroblasts separate into spaces (lacunae)
- More divisions form clusters (isogenous grps)
- These chondrocytes are embedded in extracellular matrix
19
Q
What is the term for when cartilage is replaced by bone?
A
Ossification
20
Q
In embryogenesis where is the skeletal system derived from?
A
Mesoderm germ layer
21
Q
In embryogenesis what is most of the skeleton comprised of?
A
Cartilage
22
Q
Name the two methods of growth in cartilage
A
- Appositional
- Interstitial
23
Q
What is appositional growth?
A
An increase in girth or width
24
Q
What is an interstitial growth?
A
An increase in length
25
What happens during appositional growth?
Chondroblasts deposit collagen/matrix on surface of pre-existing cartilage
26
What is interstitial growth specific for?
For endochondral bone formation
27
What happens during interstitial growth?
Chondrocytes divide and secrete matrix from within their lacunae
28
Where do chondrocytes occupy?
Hallow space
29
What are chondrocytes surrounded by?
By its own secreted matrix
30
What do chondrocytes synthesise?
- Ground substance
| - Fibrous elements
31
What does elastic cartilage contain?
Many elastic fibres
32
Where is elastic cartilage present?
In ear and epiglottis
33
What can elastic cartilage tolerate?
Repeated bending
34
What is the most abundant cartilage?
Hyaline cartilage
35
What is the appearance of hyaline cartilage?
Glassy
36
What does hyaline cartilage provide?
Support through flexibility
37
Where is hyaline cartilage present (x 5)?
- Articular cartilages
- Costal cartilage
- Larynx
- Trachea
- Nose
38
Where is fibrocartilage present (x 2)?
- Intervertebral discs
| - Pubic symphysis
39
What can fibrocartilage resist?
Strong compression and strong tension
40
What is fibrocartilage in comparison to other cartilages?
An intermediate between hyaline and elastic cartilage
41
Does cartilage have many repair capabilities?
No, limited
42
Damage of elastic and fibrocartilage
Show less damage or ageing
43
Damage of hyaline cartilage
Easily damaged & has limited repair
44
Damage of articular cartilage
Do not repair
45
What can't chondrocytes bound in hallow spaces do?
They cannot migrate to damaged areas to make new matrix
46
What is damaged cartilage replaced by?
By fibrocartilage scar tissue
47
Are they any issues of rejection in cartilage transplantation?
No
48
Why are there/ aren't there any issues of rejection in cartilage transplantation?
no issues of rejection because:
- Antigenic power of cartilage is low
- Immune system cells poorly diffuse cartilage
49
Give five diseases of cartilage
- Arthritis
- Dwarfism
- Herniated disk
- Tumors
- Scurvy
50
What happens in arthritis?
Degeneration of cartilage joints (articular cartilage)
51
What happens in dwarfism?
Reduced proliferation of chondrocytes
52
What happens in a herniated disk?
Ruptures disk cartilage ring, pushing into spine
53
What happens in tumours?
Cartilage cells give rise to benign (chondroma) tumours.
54
Do malignant tumours usually occur in cartilage?
No, in bone
55
What causes scurvy?
Lack of vitamin c required to process collagen
56
What does scurvy cause?
Defective cartilage and bone
57
Why is vitamin c required by cartilage?
To process collagen
58
How many bones are in adults?
206
59
How many bones are in infants?
About 300
60
Give six functions of bones
1. Support, Movement and Protection
2. Hematopoiesis
3. Mineral storage
4. Acid-base balance
5. Detoxification
6. Sound transduction
61
What occurs in hematopoiesis?
Red blood cells produced in red bone marrow
62
What occurs in mineral storage?
A calcium reservoir maintains calcium and phosphorus equilibrium
63
What occurs in an acid-base balance?
Blood is buffered against excessive pH changes by absorbing or releasing alkaline salts
64
What does detoxification do?
Stores heavy metals and foreign elements
65
What aspect of hearing is sound transduction involved in?
Mechanical
66
Give a physical description of cortical bones
Dense protective shell
67
Give a physical description of cancellous bones
Rigid lattice designed for strength
68
What are interstices in cancellous bone filled with?
Marrow
69
What is the location of cortical bone?
Around all bones, beneath periosteum, primarily in the shafts of long bones
70
Give location for cancellous bone?
In vertebrae, flat bones (e.g. pelvis) and the ends of long bones
71
What percentage of skeletal mass does cortical mass make up?
80%
72
What percentage of skeletal mass does cancellous mass make up?
20%
73
What is the bone matrix composed of?
- 20% Organic materials
- 70% Inorganic materials salts
- 10% Water
74
What is the name of the organic material in the bone matrix and where is it from?
Osteoid from osteoblasts
75
What is osteoid comprised of?
- Type I Collagen fibers (90% of organic osteoid part)
- Glycosaaminoglycans
- Ground substance proteoglycans
76
What are the inorganic materials in the bone matrix composed of?
Mainly Calcium & Phosphate (in form of hydroxyapatite crystals)
77
What are the four types of bone cells?
1. Osteoprogenitor cells
2. Osteoblasts
3. Osteocytes
4. Osteoclasts
78
What type of cells are Osteoprogenitor cells?
Bone stem cells
79
What is the function of Osteoprogenitor cells?
Generate osteoblasts and osteocytes
80
What type of cells are osteoblasts?
Immature bone forming cells
81
Where are osteoblasts derived from?
Mesenchymal stem cells
82
What is the most abundant cell found in bone?
Osteocytes
83
What is an osteocyte?
An inactive osteoblast
84
What type of cells are osteoclasts?
Phagocytic cells
85
What is the function of osteoclasts?
Erode bone, bone resorption and remodelling.
86
What do osteoblasts contain?
Contain lots of rough ER for collagen synthesis
87
What do osteoclasts secrete?
Secrete organic acids and lysosomal proteolytic enzymes to erode bone
88
NB! What are the six types of fixed macrophages?
1. Dust/Alveolar type (lungs)
2. Histiocytes (connective tissue)
3. Kupffer cells (liver)
4. Microglial cells (nervous)
5. Osteoclasts (bone)
6. Sinusoidal lining cells (spleen)
89
What can osteoclasts clear from the bone?
Dead osteocytes
90
What are osteoclast capable of with bone collagen
Capable of phagocytosis of bone collagen
91
What are bones?
Solid network of living cells
92
What are the four steps in the formation of bone?
1. Osteoblasts synthesise & secrete collagen & organic matrix (osteoid)
2. Osteoid then becomes calcified (i.e. calcium deposition)
3. Osteoblasts secrete vesicles of alkaline phosphatase (AP)
4. AP causes matrix mineralisation (gives rigidity & strength)
93
Mineral issues in rickets and chronic renal failure
Inadequate calcium and phosphate ions in osteiod tissue and mineralisation is slow
94
Name two types of mature bone
- Compact
| - Spongy
95
How is compact bone arranged?
In Haversian systems
96
Where is compact bone found?
Found as dense layer on outside of bones
97
Where is spongy bone found?
In interior of bone
98
Give the appearance of spongy bone
Trabecular appearance
99
Immature bone is also known as ....
Woven
100
What has more cells and ground substance, mature or immature bone?
Immature
101
What does immature bone stain more intensely with and why?
Hematoxylin as it's not mineralized
102
What is the name for the arrangement of immature bone?
Nonlamellar
103
Describe the arrangement of immature bone
Irregularly arranged collagenous fibers in proteoglycan matrix
104
Where is immature bone initially deposited?
In skeleton of fetal life or following fracture
105
Give two types of bone
- Long
| - Flat
106
How does growth occur in long bones
By endochondral ossification
107
Give two examples of long bones
- Tibia
| - Metacarpals
108
How does growth occur in flat bone?
By intramembranous ossification
109
Give the four parts of long bones
- Diaphysis
- Epiphysis
- Metaphysis
- Epiphyseal plate
110
What is the diaphysis of long bone?
A shaft consisting of marrow cavity surrounded by compact bone (little spongy bone between compact bone & marrow)
111
What is the epiphysis of long bone?
The expanded end; mainly spongy bone surrounded by thin outer shell of compact bone
112
What is the metaphysis of long bone?
The flared portion between diaphysis & epiphysis
113
What is the epiphyseal plate of long bone?
Cartilage that separates epiphyseal & diaphyseal cavities which maintains growth process
114
Give two examples of flat bone
Skull and sternum
115
Describe flat bone
Thin and plate-like
116
Name the two bone forms
- Woven (immatute)
| - Lamellar (adult)
117
What do osteoblasts produce?
Osteoid (rapidly)
118
What do osteoblasts form?
Forms random collagen fibres in osteoid
119
What does lamellar do and why? (development)
Replaces woven bone as it's stronger
120
Describe lamellar bone
Regular parallel collagen sheets
121
What does woven bone have a role in?
- Fetal bone development
- Healing fracture
- Paget's disease
122
What are the 6 zones where the transition between cartilage and new bone occurs?
1. Reserve cartilage
2. Proliferation
3. Maturation
4. Hypertrophy / calcification
5. Cartilage degeneration
6. Osteogenic
123
What does the reserve cartilage zone consist of?
Chondrocytes
124
Does proliferation occur in the reserve cartilage zone?
No
125
What happens in the proliferation zone?
Chondrocytes undergo mitotic divisions
126
What happens in the maturation zone?
Chondrocytes increase in size
127
What happens in the hypertrophy / calcification zone?
Chondrocytes and lacunae are enlarged & matrix calcified
128
What happens in the cartilage degeneration zone?
Chondrocytes degenerate
129
What happens in the osteogenic zone?
Osteoblasts commence bone formation – deposit osteoid on exposed cartilage
130
What are the five types of fractures
- Simple
- Compound/impacted
- Comminuted
- Greenstick
- Stress
131
Give the 5 steps in a bone fracture
1. Blood clot forms at fracture site (6-8h)
2. Replaced by collagen tissue
3. Chondroblasts lay down cartilage (provisional callus) (2-3 weeks)
4. Osteoblasts lay down woven bone (bony callus) (3-4 months)
5. Bony callus then remodelled to mature lamellar bone
132
What are the two types of ossification / osteogenesis
- Intramembranous ossification
| - Endochondral ossification
133
What occurs in intramembranous ossification?
Direct chondrocytes lay down bone
134
What is endochondral ossification most common in?
In fracture healing
135
What are fractures of long bones treated by?
Plaster of Paris
136
What does endochondral ossification involve as a precursor?
Involves cartilage as a precursor
137
What can fractiures be treated with in intramembranous ossification?
With internal fixation with screws/pins
138
What percentage of the bodies calcium is in bone?
99%
139
What are the two calcium compartments called?
- Bone fluid
| - Mineralised bone
140
What type of exchange occurs in bone fluid?
Fast exchange by pumps
141
What type of exchange occurs in mineralised bone?
Slow exchange by bone resorption
142
What happens in mineralised bone?
The osteoclasts phagocytic activity is increased and Ca2+ is released during low Ca2+ levels
143
What is the function of vitamin D in bone growth?
To promote osteoblast differentiation
144
What is the function of growth hormone in bone growth?
To promote osteoblast function
145
What is the function of oestrogen in bone growth?
To inhibit osteoclast
146
What is the function of calcitonin in bone growth?
To inhibit osteoclast
147
What is the function of cortisol in bone loss?
To promote osteoblast death (apoptosis)
148
What is the function of parathyroid hormone (PTH) in bone loss?
To activate osteoclast
149
What is the function of the thyroid in bone loss?
To activate osteoclast
150
What is the function of vitamin A in bone loss?
To activate osteoclast
151
What happens in bone growth?
Osteoblast is activated and osteoclast is inhibited
152
What happens in bone loss?
Osteoblast is inhibited and osteoclast is activated
153
What are the three cartilage cells?
- Mesenchymal cells
- Chondroblasts
- Chondrocytes
154
What are the four bone cells?
- Osteoprogenitor cells
- Osteoblasts
- Osteocytes
- Osteoclasts
155
What are the three different parts of development and growth of cartilage?
1. Chondrification (development)
2. Interstitial Growth (mass)
3. Appositional Growth (thickness)
156
What are the two parts in development and growth of bone?
1. Intramembranous Ossification
| 2. Endochondral Ossification
