Introduction to Connective Tissue

Introduction to Connective Tissue

• Connective tissue is a diverse group of tissues in the body providing support, structure, and connection between body parts.
• It's characterized by a matrix of extracellular fibers and ground substance surrounding cells.
• These tissues vary structurally and functionally, adapting to specific roles.

Types of Connective Tissues

• Loose connective tissue: Characterized by a loosely arranged matrix with scattered cells and abundant ground substance. It binds, supports, and packs tissues/organs.
• Dense connective tissue: Composed of densely packed fibers (collagen or elastin), less ground substance than loose. Types include dense regular, dense irregular, and elastic, each with unique properties.
• Cartilage: A specialized connective tissue with a firm, flexible matrix of collagen & elastic fibers in ground substance. Provides support and cushioning in joints, ears, and nose. Different cartilage types have varying fiber amounts and stiffness.
• Bone: A highly specialized connective tissue forming the skeleton—hard matrix of calcium phosphate and collagen. Supports the body, protects organs, and stores minerals.
• Blood: A fluid connective tissue comprising cells (red blood cells, white blood cells, platelets) suspended in plasma. Transports oxygen, nutrients, hormones, and waste.
• Adipose tissue: Specialized connective tissue storing energy as fat. Adipocytes are the fat cells in this tissue; it also provides insulation, cushioning, and hormone production.

Components of the Connective Tissue Matrix

• Extracellular fibers:
  • Collagen fibers: Provide strength and flexibility.
  • Elastic fibers: Allow stretching and recoil.
  • Reticular fibers: Provide delicate support and framework.
• Ground substance: A gel-like substance between fibers and cells, made of GAGs, proteoglycans, and adhesive glycoproteins. Consistency varies by tissue type, affecting properties.

Cells of Connective Tissue

• Fibroblasts: Most common cell type, producing extracellular fibers and ground substance.
• Chondrocytes: Cartilage cells, maintaining cartilage matrix.
• Osteocytes: Bone cells within the bone matrix, holding bone matrix and assisting in calcium homeostasis.
• Adipocytes: Fat cells storing lipids.
• White blood cells: Various types, participating in immune responses.

Key Functions of Different Connective Tissue Types

• Support: Providing structural framework (bone, cartilage).
• Connection: Connecting tissues (ligaments, tendons).
• Transport: Substances throughout the body (blood).
• Protection: Cushioning and shock absorption (adipose tissue).
• Storage: Energy (fat) and minerals (bone).
• Immune defense: Immunity, via white blood cells.

General Characteristics of Connective Tissue

• Extracellular matrix (ECM): A defining feature—providing structural support.
• Vascularity: Varying degrees of blood vessels (bone—well vascularized; cartilage—avascular).
• Nerve fibers: Variable nerve fiber distribution.

Connective Tissue and Disease

• Defects in ECM production/composition can cause various diseases.
• Some illnesses/conditions directly affect connective tissues, impacting strength, flexibility, and resilience.