Cartilage Flashcards
What is cartilage?
Semi-rigid tissue comprised of cells and ECM
What are the components of ECM?
Collagen and elastic fibers
What are the components of cartilage?
Cells - Chondroblasts, chondrocytes
Matrix- collagen fibers (type 1 or 2) and ground substance
What are chondroblasts?
Immature cells that secrete components of cartilage ECM (appositional growth)
What are chondrocytes?
Mature cartilage cells in lacunae that secrete ECM and nourish cartilage. Derived from chondroblasts. Interstitial growth
What are the three types of cartilage?
Hyaline, elastic and fibrocartilage
What type of collagen does hyaline cartilage contain?
Type II collagen
Where is hyaline cartilage found?
Articular cartilage, larynx, trachea, ribs, embryonic development
What type of collagen does Elastic cartilage have?
Type II collagen
Where is elastic cartilage located?
External ear, epiglottis, auditory tube
What type of collagen does fibrocartilage contain?
Type I collagen
Where is fibrocartilage located?
Intervertebral discs, pubic symphysis, TMJ
what is an isogenous group?
Two or three chondrocytes grouped together
What is the territorial matrix? Where is the inter territorial matrix?
Territorial - A matrix that directly surrounds isogenous group.
Interterritorial- surrounds the territorial matrix
What is the difference (in staining and characteristics) between territorial and interterritorial matrix?
Territorial is moderately staining, while territorial is less intensely stained. Territorial has decreased collagen while interterritorial has more collagen II and fewer proteoglycans
What is perichondrium?
It is dense irregular CT that surrounds hyaline and elastic cartilage. It’s a source of new cartilage cells
What is the fibrous layer of perichondrium?
The outer layer that produces type I collagen and elastin
What is the chondrogenic layer of perichondrium?
The inner layer that differentiates into chondroblasts. Secretes type II collagen
What is elastic cartilage?
Components of hyaline cartilage plus elastic fibers within the matrix; surrounded by perichondrium
What is fibrocartilage?
A combination of hyaline cartilage and dense regular CT (has type 1and type 2 collagen and a lack of perichondrium)
What is appositional growth
Chondrogenesis of new cartilage on the surface of existing cartilage; chondrogenesis cells located within inner layer of perichondrium
What is interstitial growth?
Chondrogenesis that takes place within a cartilage mass; chondrocytes divide within lacunae, creating new isogenous groups
Why is cartilage repair capacity limited?
Due to its avascular nature
What is repair cartilage?
An ECM matrix composition intermediate of hyaline and fibrous cartilage. It contains type 1 and 2. Facilitates healing of a bone fracture
Describe the components of an articular capsule
It has an outer fibrous layer made of dense regular CT and extrinsic (separate from capsule) and intrinsic (part of fibrous capsule) ligaments
Describe articular cartilage
It is hyaline cartilage, it reduces friction, its avascular and lacks nerve supply and it is nourished by synovial fluid
Describe synovial membrane
Synovium; lines joint cavities (except articular cartilage), lubricates articular cartilage, has a vascular CT membrane, produces synovial fluid, has regenerative properties and absorbs shock
What are the three components of synovial joints
Synovial membrane, articular capsule and articular cartilage
What are synoviocytes?
Cells in the joints of synovium
What are type A macrophage like synovial cells?
They are phagocytosis cells what contain lysosomes to clear articular cavities of debris formed by friction of articular cartilages. Make up 25% of the cells lining synovium. Regulate Inflammatory events
What are type B fibroblast like synovial cells?
They are cells that produce synovial fluid (plasma filtrate) and produce hyaluronate that combines with synovial fluid. They lubricate and nourish the articular cartilage.
What are the four zones of articular cartilage
Superficial (tangential)
Intermediate (transitional)
Deep (radial)
Calcified
What are three characteristics of the superficial zone of articular cartilage?
Chondrocytes are small and flattened parallel to the surface
Most superficial region is devoid of cells
Collagen fibers run parallel to surface
What are three characteristics of the intermediate zone of articular cartilage?
Chondrocytes are slightly larger and round
Occur both alone and in isogenous groups
Collagen fibers take an oblique course through the matrix
What are three characteristics of the deep zone of articular cartilage?
Large chondrocytes form radial columns
Stacks are oriented perpendicular to the articulating surface
Collagen fibers follow orientation of chondrocytes columns
What are two characteristics of the calcified zone of articular cartilage?
Rests on the underlying cortex of the bone
Matrix of the calcified cartilage layer stains slightly dark than the matrix of other layers
What is osteoarthritis?
A degenerative joint disease; characterizes by chronic joint pain and various degrees of joint deformity and destruction of articular cartilage
What happens in the early stages of osteoarthritis?
Superficial layer of articular cartilage is disrupted
What happens in the late stages of osteoarthritis?
Destruction of the cartilage extends to the bone, where the exposed subchondral bone becomes new articular surface (progressive reduction of mobility and increased pain)
