5.1 - Intro to Cartilage and Bone Flashcards
1
Q
What are chondroblasts?
A
Cells that secrete cartilage matrix
2
Q
What are chondrocytes?
A
Cells that secreted cartilage matrix and became embedded in it
3
Q
What type of cell produces cartilage matrix?
A
Chondroblasts
4
Q
What type of cell is a component of cartilage matrix?
A
Chondrocytes
5
Q
From which embryonic tissue does cartilage originate?
A
Mesenchyme
6
Q
From which embryonic tissue do chondroblasts originate?
A
Mesenchyme
7
Q
What are the 2 main components of cartilage?
A
- Cells (chondroblasts and chondrocytes)
2. ECM (collagen and proteoglycan complexes)
8
Q
What are the 2 types of cells found in cartilage?
A
- Chondroblasts
2. Chondrocytes
9
Q
What are the 2 components of cartilage’s ECM?
A
- Collagen
2. Proteoglycan complexes
10
Q
Large proteoglycan molecules have numerous side chains of ___.
A
GAGs (glycosaminoglycans)
11
Q
GAGs have strong negatively charged surfaces. What is the impact on this re: their water binding properties?
A
Strongly hydrophilic
12
Q
Why is water attracted to highly charged molecules?
A
It is polarized
13
Q
Why is cartilage well-hydrated?
A
ECM contains many GAGs, which are negatively charged and attract water molecules
14
Q
Wet cartilage swells to form a hydrated gel. What restricts the swelling of this gel?
A
Tension in the collagen network
15
Q
What is the name for the layer of dense irregular connective tissue surrounding certain types of cartilage?
A
Perichondrium
16
Q
What is the perichondrium?
A
Layer of dense irregular connective tissue surrounding certain types of cartilage
17
Q
Compare the two layers of perichondrium.
A
Outer: fibrous, contains fibroblasts, produces collagen
Inner: chondrogenic, undifferentiated, produces chondroblasts or chondrocytes
18
Q
What is the fetal precursor to bone?
A
Hyaline cartilage
19
Q
Most hyaline cartilage in the embryo is replaced by bone. What is the fate of remaining hyaline cartilage?
A
Forms growth plates and articular cartilage
20
Q
What tissue is found in nearly all joints, between bones, and in structures that must be deformable, but strong?
A
Cartilage
21
Q
What is chondrification?
A
When mesenchymal cells differentiate into chondroblasts to form cartilage
22
Q
What is a primary ossification centre?
A
First area of a bone to start ossifying
23
Q
What is a secondary ossification centre?
A
An area of ossification that appears after a primary officiation centre
24
Q
Compare primary and secondary ossification centres.
A
Primary: first site of ossification, prenatal development, located on diaphyses
Secondary: appears after primary site, postnasal and adolescent years, located on epiphyses
25
When do primary ossification centres tend to appear?
Prenatal development
26
When do secondary ossification centres tend to appear?
Postnatal and adolescent years
27
On which part of the bone do primary ossification centres usually appear?
Diaphyses
28
On which part of the bone do secondary ossification centres usually appear?
Epiphyses
29
In children, primary ossification centres appear in the diaphyses and secondary ossification centres spear in the epiphyses. Which structure separates them?
Epiphyseal growth plate
30
Bone elongation halts once the growth plates close. How are bones still able to thicken?
Mesenchymal reservoir in the periosteum capable of differentiating into osteoblasts (i.e., intramembranous ossification)
31
What cells extend the epiphyseal growth plates?
Stacks of proliferating chondrocytes
32
What are the 4 zones of bone elongation at epiphyseal growth plates?
1. Proliferation zone (cartilage cells proliferate, lengthening the bone)
2. Hypertrophic zone (older cartilage cells hypertrophy, compressing the matrix)
3. Calcification zone (matrix calcifies)
4. Ossification zone (osteoblasts lay down osteoid)
33
Which bones of the developing body are first to ossify?
Clavicles
34
What is the most commonly broken bone in the body?
Clavicle
35
Compare the epiphysis, metaphysis, and diaphysis.
Epiphysis: rounded end of a long bone
Metaphysis: narrow portion of the long bone between the epiphysis and diaphysis
Diaphysis: shaft of a long bone
36
What are the 3 types of cartilage?
1. Hyaline
2. Elastic
3. Fibrocartilage
37
What type of collagen forms hyaline cartilage?
Type II
38
What type of collagen forms elastic cartilage?
Type II
39
What type of collagen forms fibrocartilage?
Type I
40
What is the most common type of cartilage?
Hyaline
41
Is cartilage a living tissue?
Yes
42
Is cartilage innervated?
No
43
Is cartilage vascularized?
No
44
Cartilage is living, but avascular. How does it receive its nutrients?
Hyaline/Elastic: diffusion from perichondrium
| Fibrocartilage: diffusion from surrounding tissues
45
What type of connective tissue makes up the perichondrium?
Dense irregular
46
Hyaline cartilage receives its nutrients via diffusion from the ___.
Perichondrium
47
Perichondrium is usually found at the margins of hyaline cartilage. Which surface is an exception?
Articular surfaces
48
Why wouldn’t you find perichondrium lining hyaline cartilage at articular surfaces?
The perichondrium highly vascularized and innervated; the compression and movement in the area would aggravate it
49
List 2 places where you would find perichondrium.
1. Elastic cartilage
| 2. Hyaline cartilage (except on joint surfaces)
50
What type of cartilage calcifies with old age?
Hyaline
51
What is the result of articular cartilage degeneration?
Osteoarthritis
52
What is the result of articular cartilage destruction by granulating synovial membrane tissue?
Rheumatoid arthritis
53
What causes a slipped disc?
Rupture of intervertebral disc capsule
54
What type of cartilage is found in menisci?
Fibrocartilage
55
How does weight-bearing exercise protect against osteoporosis?
Encourages remodelling
56
Compare the histological appearance of hyaline cartilage, elastic cartilage, and fibrocartilage.
Hyaline: smooth ECM
Elastic: prominent elastic fibres in ECM
Fibrocartilage: prominent collagen fibres in ECM
57
Compare the location of chondroblasts and chondrocytes.
Chondroblasts: close to perichondrium
Chondrocytes: throughout ECM
58
Compare the histological appearance of chondroblasts and chondrocytes.
Chondroblasts: flattened, irregular, close to perichondrium
Chondrocytes: ovular, in lacunae, throughout ECM
59
Which cartilage cell is flat and irregular?
Chondroblasts
60
Which cartilage cell is ovular and enclosed by lacunae?
Chondrocytes
61
List 4 places where you would find elastic cartilage. (Hint: all begin with “e.”)
1. Eustachian tube
2. Ear canal
3. External ear
4. Epiglottis
62
What type of cartilage would you find in the Eustachian tube?
Elastic
63
What type of cartilage would you find in the ear canal?
Elastic
64
What type of cartilage would you find in the external ear?
Elastic
65
What type of cartilage would you find in the epiglottis?
Elastic
66
What is the name for the flap that diverts passage to the trachea or the esophagus?
Epiglottis
67
List 4 places where you would find hyaline cartilage.
1. Articular surfaces
2. Rib margins
3. Respiratory passageways
4. Tip of the nose
68
What type of cartilage would you find on articular surfaces?
Hyaline
69
What type of cartilage would you find at rib margins?
Hyaline
70
What type of cartilage would you find in the respiratory passageways?
Hyaline
71
What type of cartilage would you find in the larynx?
Hyaline
72
What type of cartilage would you find in the trachea?
Hyaline
73
What type of cartilage would you find at the tip of the nose?
Hyaline
74
List 6 places where you would find fibrocartilage.
1. Pubic symphysis
2. Menisci
3. Articular discs
4. Intervertebral discs
5. Shoulder labra
6. Hip labra
75
What type of cartilage would you find in the pubic symphysis?
Fibrocartilage
76
What type of cartilage would you find in the menisci?
Fibrocartilage
77
What type of cartilage would you find in the articular discs?
Fibrocartilage
78
What type of cartilage would you find in the intervertebral discs?
Fibrocartilage
79
What type of cartilage would you find in the shoulder labra?
Fibrocartilage
80
What type of cartilage would you find in the hip labra?
Fibrocartilage
81
What is the main function of hyaline cartilage?
Firm, flexible support
82
What is the main function of elastic cartilage?
Tolerate distortion without damage
83
What is the main function of fibrocartilage?
Strong, rigid support
84
What is endochondral ossification?
Osteoblasts from circulating osteoprogenitors invade hyaline cartilage to lay down osteoid
85
What are osteoprogenitor cells and where do they originate?
Cells that can differentiate into osteoblasts or chondrocytes
Originate from mesenchymal stem cells
86
What is osteoid?
The organic, un-mineralised portion of the bone matrix
87
What type of cells secrete osteoid?
Osteoblasts
88
What is the main component of osteoid?
Type I collagen
89
What is intramembranous ossification?
When osteoblasts differentiate from local mesenchymal cells to deposit osteoid
90
Where does intramembranous ossification take place?
Mesenchymal tissue
91
Compare endochondral ossification and intramembranous ossification.
Endochondral: osteoblasts from circulating osteoprogenitors invade hyaline cartilage to lay down osteoid
Intramembranous ossification: osteoblasts differentiate from local mesenchymal cells to deposit osteoid
92
By which method do most bones of the body develop?
Endochondral ossification
93
How do most flat bones develop?
Intramembranous ossification
94
Histologically, can you distinguish between bones arising from intramembranous ossification and bones arising from endochondral ossification?
No
95
What are the 2 ways cartilage can grow?
1. Appositional growth
| 2. Interstitial growth
96
Describe appositional growth.
Fibroblasts in the perichondrium differentiate into chondroblasts and secrete new ECM
97
Describe interstitial growth.
Chondrocytes in isogenous groups (i.e., nests) separate as they produce more ECM
98
What are isogenous groups?
Nests of chondrocytes
99
What is a lacuna?
A hollow containing a chondrocyte in cartilage or an osteocyte in bone
100
What type of cartilage forms epiphyseal growth plates?
Hyaline
101
What is an epiphyseal growth plate and what is it made of?
Site of growth near the ends of long bones
| Made of hyaline cartilage
102
How does bone grow at epiphyseal growth plates?
Chondrocytes undergo hyperplasia and hypertrophy followed by cell death and ossification
103
What happens after epiphyseal growth plates ossify?
Capacity for elongation is lost
104
Why are epiphyseal growth plates no longer visible in a fully grown adult?
Area has ossified
105
What are the 3 steps of fetal hyaline cartilage ossification?
1. Cartilage model (general shape laid down by chondrocytes; surrounded by perichondrium)
2. Bone collar (cartilage is calcified; perichondrium becomes periosteum)
3. Primary ossification centre (blood vessels and osteoblasts invade calcified matrix; osteoid laid down)
106
How might fractures increase risk of osteoarthritis?
Wear down articular cartilage, which is slow to regenerate
107
What is the most common cause of total knee and hip replacements?
Osteoarthritis
108
Compare the effects of aging on hyaline cartilage and elastic cartilage.
Hyaline: calcifies with age
Elastic: does NOT calcify with age
109
What are the 2 components of fibrocartilage?
1. Dense regular connective tissue
| 2. Hyaline cartilage
110
What type of cartilage lacks a perichondrium?
Fibrocartilage
111
Fibrocartilage has no perichondrium. From where does it receive its nutrition?
Surrounding tissues
112
What are the 2 primary function of menisci in the knee?
1. Provide CUSHIONING between tibia and femur
| 2. Prevent DEGENERATION of articular cartilage underneath
113
Compare the most common causes of meniscal lesions in young people and middle-aged/elderly people.
Young: sports-related injuries
| Middle-aged/elderly: degeneration from overuse
114
What are the 5 main functions of bone?
1. Provide support
2. Protect organs
3. Enable movement
4. Store minerals
5. Produce RBC and WBC
115
Compare the axial and appendicular skeleton.
Axial: bones of the head, neck, and trunk
Appendicular: bones of the limbs, shoulder, and pelvis
116
What are 3 areas that make up the axial skeleton?
1. Head
2. Neck
3. Trunk
117
What are 3 areas that make up the appendicular skeleton?
1. Limbs
2. Shoulder
3. Pelvis
118
What are the 6 bone shapes?
1. Long
2. Short
3. Flat
4. Irregular
5. Sesamoid (round bones that reinforce tendons)
6. Pneumatic (contain air spaces)
119
What type of bone reinforces tendons?
Sesamoid
120
What type of bone contains air spaces?
Pneumatic
121
Bone is composed of both organic and inorganic matter. The ___ minerals give it its rigidity.
Organic
122
Bone is composed of both organic and inorganic matter. The ___ collagen gives it its flexibility/resistance to tension.
Inorganic
123
What gives bone its rigidity?
Minerals (i.e., calcium hydroxyapatite crystals)
124
What gives bones its flexibility/resistance to tension?
Collagen
125
What are the 2 types of bones?
1. Spongy bone
| 2. Compact bone
126
What is a synonym for compact bone?
Cortical bone
127
Spongy bones consists of fine, bony columns. What fills the spaces?
Bone marrow
128
Describe the structure of spongy bone.
Fine, bony columns with bone marrow filling the spaces
129
What type of bone is abundant in the epiphysis?
Spongy bone
130
Where would you find compact bone?
External surfaces of bones
131
What percentage of skeletal mass is formed by cortical bone?
80%
132
Compare the placement of Haversian canals and Volkmann’s canals.
Haversian: at the centre of osteons
Volkmann: connecting adjacent osteons to the periosteum; PERPENDICULAR to Haversian canals
133
What are Haversian canals?
Channels of nerves, vessels, and lymphatics at the centre of osteons
134
What are Volkmann’s canals?
Channels of nerves, vessels, and lymphatics connecting the periosteum to osteons
135
What is an osteon?
Basic unit of cortical bone; consists of lamellae surrounding a Haversian canal
136
What is the periosteum?
Dense irregular connective tissue covering bones, except at articular surfaces
137
What is a lamella?
A concentric layer of bone tissue
138
What do lacunae contain in bone?
Osteocytes
139
What do lacuna contain in cartilage?
Chondrocytes
140
What are canaliculi?
Tiny canals connecting adjacent lacunae
141
How do osteocytes communicate with each other?
Via canaliculi
142
Does spongy bone contain either Haversian or Volkmann’s canals?
No
143
What are trabeculae?
Honeycomb-like bone tissues found in spongy bone
144
Compare the internal structure of osteons and trabeculae.
Osteons: DO contain Haversian and Volkmann’s canals, round lamellae
Trabeculae: DO NOT contain Haversian or Volkmann’s canals, irregularly-shaped lamellae
145
What are the 2 types of cells found in bone marrow?
1. Adipose (yellow marrow)
| 2. Hemopoietic (red marrow)
146
What is a spicule?
Projection of new forming bone
147
Compare the location of osteoblasts, osteoclasts, and osteocytes in an osteon
Osteoblasts: near edges
Osteoclasts: near edges
Osteocytes: all over
148
Compare the functions of osteoblasts, osteoclasts, and osteocytes.
Osteoblasts: build bone
Osteoclasts: break down bone
Osteocytes: maintain bone
149
What is a cutting cone?
A bone remodelling unit; osteoclasts break down bone and trailing osteoblasts lay down new bone
150
What are the 3 zones of a cutting cone?
1. Cutting zone
2. Reversal zone
3. Closing zone
151
Compare the activities occurring in the 3 regions of a cutting cone.
Cutting zone: osteoclasts break down bone
Reversal zone: mix of osteoclast and osteoblast avidity
Closing cone: osteoblasts lay down new bone
152
How would you increase the number of cutting cones you have?
Mechanical loading
153
What happens to bone density in outer space?
Decreases due to reduction in gravitational forces
154
How does sport cause bone hypertrophy?
Increased remodelling
155
List 3 factors that decrease rate of bone remodelling.
1. Low gravity
2. Age
3. Inactivity
156
Normally, lamellae are able to slip relative to each other to help disperse forces. What happens when this fails?
Fracture
157
Why would a bone fracture cause pain?
Damage to nerves
158
What are the 4 steps of fracture repair?
1. Hematoma formation (blood clot)
2. Fibrocartilaginous callous formation (fibres and cartilage)
3. Bony callus formation (spongy bone)
4. Remodelling (compact bone)
