Histology

Overview of Tissues

• Tissues are groups of similar cells with shared structure and function.
• Four main tissue groups: Epithelial, Connective, Muscle, Nervous.

Epithelial Tissues

• Found on surfaces, involved in protection, absorption, and secretion.
• Types: External surfaces (e.g., Epidermis) and lining of tubes (lumen).
• Glandular epithelia involved in secretion (exocrine glands).

Key Features of Epithelial Tissues

• Polarity: Cells have apical (exposed) and basal (attached) surfaces.
• Basal Lamina: Connects epithelial tissue to underlying connective tissue.
• Basement Membrane: Composed of basal and reticular lamina; anchors epithelium.
• Cell Junctions: Tight junctions and desmosomes keep cells tightly packed with minimal space.
• Avascular: No blood vessels; rely on diffusion from connective tissues for nutrients.
• High Mitotic Rate: Rapid cell division due to wear and tear; leads to higher cancer risk in epithelial tissues.