Overview
This lecture explains the structure, composition, cells, and growth mechanisms of hyaline cartilage, a connective tissue that plays a crucial role in bone development and joint function.
Role and Location of Hyaline Cartilage
- Most bones originate as hyaline cartilage, which is later converted to bone.
- Growth plates in developing bones and the ends of long bones (articular surfaces) consist of hyaline cartilage.
- Articular cartilage provides a smooth, durable surface at joints.
Structure and Composition of Hyaline Cartilage
- Hyaline cartilage's properties come from its extracellular matrix, made of ground substance and fibers.
- The ground substance consists of hyaluronic acid (central backbone) with branching proteoglycans.
- Collagen and elastic fibers are embedded in the matrix, adding strength and resiliency.
- The matrix is semi-solid, strong, and resists compression.
Cells Associated with Hyaline Cartilage
- Chondroblasts are cells on the cartilage surface that produce new matrix.
- Once surrounded by matrix, chondroblasts become chondrocytes.
- Chondrocytes reside in lacunae within the matrix and can also produce new cartilage.
Surrounding Layers and Special Features
- The perichondrium is a two-layered structure surrounding cartilage, with an outer fibrous layer and an inner chondrogenic layer containing chondroblasts.
- The perichondrium becomes the periosteum when blood vessels enter.
- Articular cartilage does not have a perichondrium.
Growth of Hyaline Cartilage
- Appositional growth: new matrix is added to the surface by chondroblasts.
- Interstitial growth: new matrix is formed within the cartilage as chondrocytes divide.
Key Terms & Definitions
- Hyaline cartilage â a type of connective tissue found at bone joints and in developing bones.
- Extracellular matrix â the non-cellular component that provides structural support in tissues.
- Hyaluronic acid â a long, unbranched polysaccharide in the cartilage ground substance.
- Proteoglycan â complex molecules branching from hyaluronic acid, part of the ground substance.
- Collagen fibers â protein fibers providing strength in cartilage.
- Chondroblast â a cell producing new cartilage matrix on the surface.
- Chondrocyte â a mature cartilage cell housed in a lacuna, capable of producing new matrix.
- Lacunae â small cavities in the cartilage matrix housing chondrocytes.
- Perichondrium â a dense connective tissue layer surrounding cartilage, with fibrous and chondrogenic layers.
- Appositional growth â growth by adding matrix to the surface of cartilage.
- Interstitial growth â growth by producing matrix within the existing cartilage.
Action Items / Next Steps
- Review diagrams of hyaline cartilage to identify labeled components.
- Study the differences between appositional and interstitial growth for potential quiz questions.