Flashcards in Cartilage Deck (15):
What is cartilage?
Avascular tissue consisting of an extensive ECM in which lie chondrocytes (produce and maintain the ECM).
What is the ground substance of cartilage composed of? How does this composition determine the properties of cartilage?
- Hyaluronate proteoglycan aggregates: hyaluronic acid molecules forming linear aggregates, each with many proteoglycan monomers (core protein joined to 100 GAG units).
- Network of type 2 collagen fibrils.
- Large ratio of GAGs : collagen - ready diffusion of substances between chondrocytes and blood vessels surrounding the cartilage.
- Large amount of hyaluronic acid assists resilience - pliable and therefore resistant to repeated application of pressure.
- High density of negative charges on GAGs attracts water - forms hydrated gel.
What are the 3 major types of cartilage?
Describe the matrix and cells of hyaline cartilage.
Matrix: hyaluronate proteoglycan aggregates are bound to fine collagen matrix fibres.
Chondrocytes are present singly or, if recently divided, as small clusters (isogenous groups). Each chondrocytes lies in a lacuna.
Where is hyaline cartilage located?
Parts of rib cage
Trachea (C rings), bronchi & larynx
What is the role of hyaline cartilage in early foetal development?
Acts as a precursor model for those bones which develop by endochondral ossification (mineralised to form bone). As long bones develop, some hyaline cartilage remains at articulating surface.
Describe the matrix and cells of elastic cartilage.
Matrix is like that of hyaline but with addition of many elastic fibres and elastic lamellae. Confers elasticity as well as resilience.
Where is elastic cartilage located?
External ear (pinna)
External acoustic meatus
Describe the matrix and cells of fibrocartilage.
Fibrocartilage = combination of dense regular connective tissue and hyaline cartilage.
Matrix is like that of hyaline but with addition of abundant type I collagen fibres. Has resilience to act as shock absorber and to resist shearing forces.
Contains chondrocytes and fibroblasts. Cells often distributed in rows or as isogenous groups.
Where is fibrocartilage located?
Articular discs of sternoclavicular and temporomandibular joints
Menisci of knee joint
What are synovial joints?
Moveable joint in which the juxtaposed bone ends are:
- covered by hyaline cartilage or fibrocartilage
- lie within lubricating synovial fluid bounded by an articular capsule which is lined by synovial membrane and reinforced with fibrous tissue and ligaments.
What are the 2 types of hyaline cartilage growth?
1. Appositional growth (from periphery)
2. Interstitial growth (from within the cartilage)
Describe the process of appositional growth.
1. Fibroblast-like cells of perichondrium give rise to flat, newly formed chondroblasts.
2. Chondroblasts secrete matrix and round up to develop into chondrocytes.
Describe the process of interstitial cartilage growth.
1. Chondrocytes deeper within the cartilage divide and give rise to isogenous groups.
2. Deposition of further matrix by isogenous groups.
3. Cells of isogenous groups separate as they lay down matrix.