Lecture Notes: Connective Tissue

Overview

Connective tissue is the most abundant tissue type and provides a protective structural framework for other tissues.
Functions: binding, support, protection, insulation, storage, and transportation.
All connective tissues are derived from mesenchyme (embryonic tissue) and consist of cells with an extensive extracellular matrix.

Ground Substance
- Material that fills space between cells.
- Composed of interstitial fluid, cell adhesion proteins, and proteoglycans.
Fibers
- Part of the extracellular matrix.
- Types:
  - Collagen Fibers: Strongest and most abundant protein (collagen), stronger than steel.
  - Elastic Fibers: Made of elastin, stretchy and form networks.
  - Reticular Fibers: Similar to collagen but form networks supporting tissues.
Cells
- Can be mature or immature (actively mitotic). Immature cells secrete ground substance and fibers.
- Naming suffixes:
  - "-blast" for immature cells.
  - "-cyte" for mature cells.
- Types:
  - Fibroblasts/Fibrocytes: Connective tissue proper.
  - Chondroblasts/Chondrocytes: Cartilage.
  - Osteoblasts/Osteocytes: Bone.
  - Hematopoietic Stem Cells: Blood.

Loose Connective Tissue
- Areolar: Supports/binds other tissues, stores tissue fluid (most abundant).
- Adipose: Fat cells, nutrient storage, insulation.
- Reticular: Similar to areolar but supports certain structures.
Dense Connective Tissue
- Regular: Organized collagen fibers, forms tendons/ligaments.
- Irregular: Unorganized collagen, resists tension in many directions.
- Elastic: Similar to dense regular but more elastic.

Withstands tension and compression.
Lacks nerve cells and blood vessels, relies on diffusion for nutrients.
Types:
- Hyaline Cartilage: Most abundant, amorphous but firm.
- Elastic Cartilage: Similar to hyaline with more elastic fibers.
- Fibrocartilage: Rows of chondrocytes and collagen, compressible and strong.