Cartilage Types and Functions

Cartilage Overview

• Cartilage is a specialized connective tissue, supporting soft tissues, providing a smooth surface for joints, and enabling long bone development.
• It's composed of a dense network of collagen fibers embedded in chondroitin sulfate—a gel-like ground substance.
• Cartilage withstands more stress than loose and dense connective tissues.
• Cartilage types differ in their collagen fiber arrangement, presence of perichondrium, and strength.

Cartilage Types and Features

• Hyaline cartilage: Thin, fine collagen fibers, prominent chondrocytes in lacunae, most hyaline cartilage is surrounded by perichondrium (except articular cartilage, which is in joints and epiphyseal plates). It provides flexibility and support, reducing friction and absorbing shock in joints. It's the weakest of the three.

• Fibrocartilage: Thicker bundles of collagen fibers, chondrocytes scattered throughout, lacks perichondrium, strong and rigid. It offers support and maintains shape

• Elastic cartilage: Threadlike network of elastic fibers, chondrocytes located within the extracellular matrix, perichondrium is present, support and shape maintenance (elasticity). It's the second strongest.

Cartilage Roles

• Support for soft tissues.
• Smooth, gliding surface for bone articulations at joints.
• Development and growth of long bones.

Cartilage Classification

• Information on cartilage classification was presented as a diagram, not text.

Cartilage Components

• Cells:

  • Chondroblasts: immature cells, produce extracellular matrix
  • Chondrocytes: mature cells, maintain extracellular matrix. Cells can be found singly or in groups within lacunae (small spaces in the matrix).

• Fibers:

  • Meshwork of collagen (mainly Type 2). Collagen arrangement strengthens and holds the gel-like ground substance.

• Ground substance: Proteoglycans, complex macromolecules with core proteins attached to glycosaminoglycans (GAGs). Proteoglycans help bind water, creating a "molecular sponge," and allowing cartilage to function properly.

Cartilage Loading

• Onloading: Fluid pressure rises, cartilage deforms, water moves out—similar to squeezing a wet sponge.
• After removal of load: Fluid pressure drops, cartilage returns to normal shape.

Cartilage Zones (Collagen Arcade)

• Superficial horizontal collagen fibers (superficial tangential, middle, and deep zones).
• Intermediate layer (collagen arcade).
• Deep vertical collagen fibers

Cartilage Nutrition

• Articular cartilage receives nutrition through diffusion from underlying subchondral bone, synovial membrane at the cartilage periphery, and synovial fluid in the joint.

Perichondrium

• A layer of dense connective tissue surrounding most cartilage surfaces.
• Articular cartilage (and some hyaline cartilage) lacks perichondrium.

Cartilage Healing & Repair

• Cartilage is relatively inactive and grows slowly.

• Cartilage has low regeneration ability, mainly in young individuals due to its avascular nature.

• In adults, damage leads to fibrous scar tissue formation lacks hyaline cartilage properties.

• Growth patterns:

  • Interstitial growth: Occurs in young, pliable cartilage during childhood and adolescence
  • Appositional growth: Occurs later and continues in adulthood.

Other information

• Information on further reading was provided.

Explore the fascinating world of cartilage in this quiz. Learn about the different types of cartilage, their unique features, and their roles in the human body. Test your knowledge on hyaline and fibrocartilage and understand how they contribute to joint function and overall skeletal health.