Cartilage Types and Functions

Cartilage

• Cartilage is a connective tissue composed of chondrocytes and an extracellular matrix.
• The extracellular matrix makes up more than 95% of cartilage's volume.
• Cartilage is avascular, meaning it lacks blood vessels.
• The extracellular matrix is essential for the diffusion of substances between chondrocytes and blood vessels in surrounding connective tissue.

Types of Cartilage

• Hyaline Cartilage
  • Contains type II collagen fibers, GAGs, proteoglycans, and multiadhesive glycoproteins.
  • Found in articular surfaces of joints (articular cartilage), rib cage (costal cartilages), trachea, bronchi, larynx, and nose.
  • The perichondrium surrounds hyaline cartilage, except on articular surfaces.
  • Spaces called lacunae contain chondrocytes.
  • The extracellular matrix of hyaline cartilage appears glassy and is produced by chondrocytes.
  • Chondrocytes are distributed singularly or in clusters called isogenous groups.
• Elastic Cartilage
  • Contains elastic fibers and elastic lamellae in addition to the matrix material of hyaline cartilage.
  • Found in the external ear, middle ear, and larynx.
  • The elastic material gives elastic cartilage properties in addition to resilience and pliability, characteristic of hyaline cartilage.
  • Always surrounded by the perichondrium.
• Fibrocartilage
  • A combination of dense regular connective tissue and hyaline cartilage.
  • Contains abundant type I collagen fibers and the matrix material of hyaline cartilage.
  • The chondrocytes are dispersed among the collagen fibers singularly, in rows, and isogenous groups.
  • The chondrocytes appear similar to hyaline cartilage chondrocytes but have considerably less cartilage matrix material.
  • No surrounding perichondrium.
  • Found in intervertebral discs, the pubic symphysis, articular discs, menisci of the knee joint, etc.
  • Serves as a shock absorber.
  • Resist both compression and shearing forces.

Bone

• Bone is a specialized form of connective tissue comprised of cells and an extracellular matrix.
• The matrix is mineralized, making the tissue hard and providing support and protection.
• Contains spaces called lacunae, which house bone cells, or osteocytes.
• Osteocytes extend processes into small tunnels called canaliculi.
• Canaliculi connect adjacent lacunae, allowing contact between neighboring osteocytes.
• Mature (lamellar) bone is mostly composed of osteons (Haversian systems), which are concentric lamellar structures organized around an osteonal (Haversian) canal.
• The osteonal canal houses the vascular and nerve supply of the osteon.
• Perforating (Volkmann's) canals are perpendicular to osteonal canals and connect them to each other.
• Lacunae between concentric lamellae contain osteocytes, interconnected via canaliculi.

Cartilage

• Cartilage is a type of connective tissue composed of chondrocytes (cells) and a specialized extracellular matrix.
• Cartilage is avascular, meaning it doesn't have blood vessels.
• Extracellular matrix makes up over 95% of cartilage volume and is essential for substance diffusion between chondrocytes and blood vessels.

Types of Cartilage

• Hyaline Cartilage: Contains type II collagen fibers, GAGs (glycosaminoglycans), proteoglycans, and multiadhesive glycoproteins.

  • Contains lacunae, which house chondrocytes.
  • Matrix appears glassy and homogenous due to chondrocyte production.
  • Chondrocytes are found individually or in clusters called isogenous groups.
  • Contains three types of GAGs: hyaluronan, chondroitin sulfate, and keratan sulfate.
  • Surrounded by perichondrium, a connective tissue, except on articular surfaces.
  • Found in articular surfaces of joints (articular cartilage), rib cage (costal cartilages), trachea, bronchi, larynx, and nose.

• Elastic Cartilage: Contains the same components as hyaline cartilage, but also contains elastic fibers and lamellae, giving it more elasticity.

  • Always surrounded by perichondrium.
  • Found in the external ear, middle ear, and larynx.

• Fibrocartilage: Combines features of dense regular connective tissue and hyaline cartilage.

  • Chondrocytes are dispersed among collagen fibers individually, in rows, or isogenous groups.
  • Chondrocytes have less cartilage matrix material than hyaline cartilage chondrocytes.
  • No surrounding perichondrium.
  • Found in intervertebral discs, pubic symphysis, articular discs, menisci of the knee joint, and other areas.
  • Acts as a shock absorber due to its resistance to compression and shearing forces.

Bone

• Bone is a specialized connective tissue with cells and extracellular matrix.
• Distinguished by its mineralized matrix, which gives it hardness, support, and protection.

Bone Structure

• Bone matrix contains lacunae, which house osteocytes (bone cells).
• Osteocytes have processes that extend into canaliculi, small tunnels through the mineralized matrix.
• Canaliculi connect adjacent lacunae, allowing communication between osteocytes.
• Mature bone (lamellar bone) is mostly composed of osteons (Haversian systems).
  • Concentric lamellae (layers) organized around an osteonal canal, which contains blood vessels and nerves.
  • Perforating (Volkmann's) canals connect osteonal canals perpendicularly.
  • Lacunae between lamellae contain osteocytes connected by canaliculi.

This quiz covers the structure and types of cartilage, including hyaline and elastic cartilage. Learn about the composition, functions, and specific locations of different cartilage types in the human body. Perfect for biology students studying connective tissues.