L13: Cartilage Flashcards
1
Q
Basic types of tissue
A
- ) Epithelium
- ) Muscle tissue
- ) Nervous tissue
- ) Connective tissue
2
Q
Under what tissue type does cartilage fall?
A
- Connective tissue. It is a specialized CT
3
Q
Name three types of cartilage
A
- Hyaline cartilage (glassy cartilage)
- Elastic cartilage
- Fibrocartilage
4
Q
Hyaline cartilage. Where is it located? Give examples.
A
- In places where it maintains a lumen / space open. Ie. in larger respiratory passages – nasal cartilages, larynx, trachea and bronchi
- At articular surfaces of bones. Eg. Costochondral joints, head of femur
- At epiphyseal plates of growing bones
5
Q
What are the components of hyaline cartilage’s ECM?
A
- Proteins: mainly type II collagen
- Proteoglycans (hyaluronan present) and glycoproteins (fibronectin present)
- Extracellular fluid (bound by GAGs of proteoglycans – acts as diffusion medium)
6
Q
Describe the histogenesis of hyaline cartilage
A
- Hyaline cartilage is derived from mesenchymal cells found in embryonic CT known as mesenchyme.
- These cells retract their cell processes and become round-shaped cells.
- They form chondrification centers, which are future cartilage sites
- They then differentiate into chondroblasts which synthesize cartilage’s ECM.
- As they deposit more and more ECM, they become trapped with lacunae of the ECM
- After being trapped, they are called chondrocytes
- These cells may further divided within their lacunae. The group of cells within a lacunae are known as isogenous groups , which are genetically uniform cells. These cells synthesize ECM as necessary and contribute to interstitial growth of cartilage.
7
Q
What is perichondrium? Where is it found? Discuss the histological characteristics and function of each of its’ layers. What does each layer consist of?
A
- Perichondrium is membranous CT capsular layer that covers only hyaline and elastic cartilage (not fibrocartilage) and is derived from mesenchymal cells.
1. ) Outer layer = fibrous layer. Consists of dense collagenous CT with type I collagen, fibroblasts, blood vessels, nerves and lymphatics. The cartilage itself is without nerves, blood and so this component of perichondrium serves to provide cartilage with nutrients and oxygen, removing waste that diffuses through extracellular fluid that composes cartilage. Therefore, this layer is protective and supportive.
2. ) Inner layer = cellular layer. Consists of chondrogenic cells that divide and differentiate into chondroblasts and form ECM. This layer contributes to the appositional growth of cartilage, growth occurring on surface. Allows for growth and maintenance of cartilage.
8
Q
Describe interstitial and appositional growth of cartilage
A
- Interstitial growth refers to growth occurring during embryologic develop, articular cartilage growth, growth in epiphyseal plates (lengthening bone). This is growth that occurs deep within the inside of cartilage and occurs as a result of isogenous groups.
- Appositional growth refers to growth of most cartilage throughout its’ lifespan. This is growth that occurs at outer surface of cartilage and occurs as a result of the inner cellular layer of perichondrium.
9
Q
Discuss cell types of cartilage
A
- Cartilage arises of mesenchymal cells
- Mesenchymal cells give rise to chondrogenic cells that reside in chondrification centers (centers that give rise to cartilage) and in inner cellular layer of perichondrium.
- Chrondrogenic cells differentiate into chondroblasts, which are the matrix and fiber synthesizing cells of cartilage. Chondrogenic cells can differentiate into osteoprogenitor cells.
- Chondrocytes are chondroblasts when they become trapped within lacunae and function to maintain matrix. Also contribute to interstitial growth.
10
Q
What are the capsular, territorial and interterritorial matrices found in cartilage?
A
- ) Capsular (pericellular) matrix: highest concentration of sulfated proteoglycans, hyaluronan and glycoproteins with fine collagen fibers woven around each chondrocyte. Stains dark blue.
- ) Territorial matrix: lighter-staining matrix surrounding each isogenous group made up of same composition as above, just in lower concentration. Stains lighter blue.
- ) Interterritorial matrix: represents majority of matrix (ie. everything not mentioned above), has same composition as above, in lower concentration.
11
Q
Is cartilage vascularized? Does it contain nerves or lymphatics?
A
- It is avascular, no nerves, arteries, veins or lymphatics.
12
Q
What forces does hyaline cartilage resist?
A
- Tension and compressive forces
13
Q
Elastic cartilage. How does it compare to hyaline cartilage? Histological characteristics. Where is it located?
A
- Similar to hyaline cartilage, but also contains elastic fibers in its ECM and in the fibrous layer of its perichondrium.
- More and larger chondrocytes than hyaline cartilage. Elastic fiber bundles are more prominent in territorial matrix. Provides more flexibility and elasticity than hyaline cartilage.
- Found in pinna of ear, internal and external auditory tubes, epiglottis and larynx.
14
Q
Fibrocartilage. Describe (including contents). Histological characteristics. Where is it located?
A
- Transitional form between dense CT and hyaline cartilage. It contains type I collagen instead of type II. These thick bundles of collagen are not present in hyaline or elastic cartilage.
- Lacks perichondrium
- Chondrocytes occur in groups or parallel rows alternating with thick bundles of collagen. Fibroblasts are present.
- Located: annulus fibrosus of IV disc, pubic symphysis, articular disc in TMJ, menisci of knee, at junction bw tendons and bone.
- Provides tough and tensile strength support
15
Q
What is osteoarthritis, how does it occur?
A
- Osteoarthritis means inflammation at the bone of a joint
- As one ages, GAGs become less hydrated and this results in thinner cartilage. The cartilage develops fissures and eventually bone articulates with bone causing sanding down of tissue. Bone becomes inflamed and develops cysts. Extremely painful
