Connective Tissue Functions and Characteristics

Connective Tissue Functions and Characteristics

• Connective tissue provides structure to tissues and organs (e.g., bones, ligaments).
• It protects organs by providing immune defence, wound healing, and cushioning.
• It facilitates transport of nutrients, water, and waste products (e.g., blood).
• It insulates and stores energy (e.g. fat tissue).
• Connective tissue is composed of cells, fibers, and an extracellular matrix (ECM).

Extracellular Matrix (ECM)

• The ECM is a gel-like substance surrounding and supporting cells.
• It's composed of water, proteins, glycoproteins, and glycosaminoglycans.
• The ECM provides structural integrity and facilitates transport of nutrients and waste.
• Its properties differ depending on the tissue type (e.g., calcified in bone, flexible in cartilage).

Connective Tissue Cells (Fixed and Transient)

• Fixed cells:
  • Fibroblasts: produce and maintain fibers (collagen, elastic) and ECM.
  • Adipocytes: store fat for energy, insulation, and cushioning.
  • Macrophages: engulf pathogens and dead cells (immune defense).
  • Mast cells: release histamine during allergic reactions, contributing to inflammation.
• Transient cells:
  • Plasma cells: produce antibodies to combat infections.
  • Eosinophils: combat parasites and participate in allergic responses.

Connective Tissue Fibers

• Collagen fibers: thick fibers providing tensile strength, resisting stretching; abundant in tendons and ligaments.
• Elastic fibers: thin fibers allowing tissues to stretch and recoil; found in skin, lungs, and arteries.
• Reticular fibers: thin, branching fibers forming a mesh-like structure supporting soft tissues like spleen and lymph nodes.

Types of Connective Tissue (Proper and Specialized)

• Connective Tissue Proper:

  • Loose connective tissue (Areolar): binds skin to underlying structures, supports blood vessels.
  • Loose connective tissue (Adipose): stores fat, insulates the body, cushions organs.
  • Loose connective tissue (Reticular): supports lymphoid organs (e.g., spleen, lymph nodes).
  • Dense Regular Connective Tissue: parallel collagen fibers for strength (tendons, ligaments).
  • Dense Irregular Connective Tissue: densely packed fibers in random directions for strength (dermis).
  • Elastic Connective Tissue: contains mostly elastic fibers for stretch and recoil (arteries, lungs).

• Specialized Connective Tissue:

  • Cartilage (hyaline, fibrocartilage, elastic).
  • Bone (compact and spongy bone).
  • Blood: transports oxygen, nutrients, waste; involved in immune defense and clotting.