Cartilage Flashcards
What is cartilage?
A dense supportive connective tissue that consists of cells (chondrocytes), fibers, and ground substance
Is cartilage vascularized?
No, no capillary bed
How does the lack of vascularization affect cartilage?
Limits the thickness of cartilage
Thick cartilage has vascular canals
What are the types of cartilage?
Hyaline, fibrocartilage, elastic cartilage
What are examples of hyaline cartilage?
Developing bones, growth plates, articular surfaces, respiratory tracts
What are examples of fibrocartilage?
Intervertebral discs, cardiac skeleton, some tendon/muscle to bone connections
What are examples of elastic cartilage?
Epiglottis, pinna
What are chondrocytes?
Chondrocytes are mature cells that are within the spaces of the cartilage extracellular matrix
Do chondrocytes occur singly or in groups?
Both singly and in isogenous groups
What are chondrocytes responsible for?
Production and Maintenance of cartilage
What cells differentiate in to chondrocytes?
Mesenchymal cells
What do chondrocytes look like?
Round with basophilic nucleus
When do mesenchymal cells become chondrocytes?
When mesenchymal cell is surrounded by extracellular matrix
What is a lacunae?
The space in the extracellular matrix that is occupied by the chondrocyte
Defining characteristics of lacunae
Good contrast between the chondrocyte and the matrix
Chondrocytes usually shrink more than the extracellular matrix
Which characteristic is used to easily define cartilage?
Presence of lacunae
What is ground substance made of?
Proteoglycan aggregates (made of many GAGs)
Hyaluronic acid is the most important one for binding aggregates
Is ground substance hydrophilic?
Yes, proteoglycans absorb 50x their dry weight in interstitial fluid
Why is the ground substance resilient?
Negative charge of GAGs repel each other
How do chondrocytes receive nutrition?
Nutrients and waste products diffuse through the extracellular matrix
Proteoglycan aggregates hold extracellular fluid which can be squeezed in and out of cartilage
Do chondrocytes connect?
No, chondrocytes do not contact each other
What is the perichondrium?
dense irregular connective tissue that surrounds cartilage
What are the 2 layers of perichondrium?
Inner layer is chondrogenic (cells of inner layer are chondroblasts)
Outer layer is typical fibrous connective tissue
Is perichondrium present on articular or fiborcartilaginous cartilage?
No
What are the directions of cartilage growth?
Appositional or interstitial
What is appositional growth?
New cartilage is deposited on the surface of existing cartilage under the perichondrium
Chondroblasts in the inner layer become trapped by their own products and become chondrocytes
What is interstitial growth?
Cartilage tissue expands from within the tissue
Chondrocytes within the cartilage divide and produce more cartilage
What are isogenous groups?
Evidence of interstitial growth
Results from division of chondrocytes in the lacunae
As the tissue grows, the cells become more separated
What type of collagen is present in the extracellular matrix?
Fine collagen fibers (type II)
This gives the extracellular matrix a glassy appearance
What color does the ground substance stain?
Basophilic
Chondrocytes occur randomly singly or in isogenous groups in hyaline cartilage, what are the exceptions to this?
Growth plates and articular cartilage are more structured
What are the zones of articular cartilage?
Superficial zone has flattened chondrocytes and collagen fibers are parallel to the joint surface
The middle zone has round lacunae and collagen fibers that arc towards the underlying bone
How to tell elastic cartilage from hyaline cartilage?
Elastic fibers will contrast with the ground substance
Where is elastic cartilage found?
E- Epiglottis, External Ear, Eustacian tube
What type of fibers does fibrocartilage have?
Large collagen fibers to help with tendons and ligaments, intervertebral discs and symphyses
How are cells arranged in fibrocartilage?
Rounded cells in lacunae and arranged in rows between collagen fibers
How to tell apart fibrocartilage and dense regular connective tissue?
Round cells in lacunae
