Lecture Notes on Animal Tissues

Introduction to Animal Tissues

• Animal tissues are numerous due to the many functions animals perform simultaneously.
• Simplified study by categorizing into four major types based on function:
  • Protection
  • Connection
  • Movement and Locomotion
  • Transmission of Signals

Major Types of Animal Tissues

1. Epithelial Tissue
2. Connective Tissue
3. Muscular Tissue
4. Nervous Tissue

Epithelial Tissue

• Definition: Epithelial tissue lies above the body surface forming a protective covering.
• Functions:
  • Serves as a barrier between organs.
  • Controls permeability of substances entering/exiting cells.

Structural Characteristics

• Tightly packed cells with no intercellular spaces.
• Minimal cementing material present between cells.
• All epithelial cells rest on a Basement Membrane:
  • Provides support and aids in holding cells in a uniform layer.

Types of Epithelia Based on Function

1. Simple Squamous Epithelium

   • Function: Filtration
   • Structure: Flat surface.

2. Columnar Epithelium

   • Function: Absorption and secretion
   • Structure: Tall pillar-like cells for larger surface area.

3. Cuboidal Epithelium

   • Function: Strength and support with larger surface area.
   • Structure: Cube-like cells.

4. Glandular Epithelium

   • Function: Specialized secretions (hormones, enzymes).
   • Structure: Modified cells known as gland cells.

Conclusion

• Summary of epithelial tissue structure and functions.
• Next discussion will cover the four types of epithelia in detail.