Tissue Overview and Epithelial Tissue Quiz

Tissue Overview

• Tissue is an aggregation of similar cells and cell products that perform a common function.
• Classification includes plant and animal cells based on structure and function.

Epithelial Tissue

• Functions: Covers surfaces and is involved in protection, absorption, filtration, and secretion.
• Characteristics:
  • Composed of closely fitting cells forming sheets.
  • Contains little extracellular material, with a basement membrane.
  • Avascular, relying on diffusion from underlying connective tissues for nourishment.
  • Capable of easy regeneration if well nourished.
• Locations include body coverings, linings, and glandular tissues.

Classification of Epithelia

• By Number of Layers:
  • Simple epithelium: One cell layer.
  • Stratified epithelium: Multiple cell layers.
  • Pseudostratified epithelium: One layer appearing as multiple.
  • Transitional epithelium: Stratified and stretchy.
• By Shape of Cells:
  • Squamous: Flat and thin cells.
  • Cuboidal: Cube-like cells.
  • Columnar: Tall and thin cells.

Functions of Epithelial Tissue

• Protects underlying structures (e.g., skin, oral mucosa).
• Acts as barriers (e.g., outer layer of skin).
• Permits passage of substances (e.g., lung epithelium).
• Secretes substances (e.g., mucus and sweat glands).
• Absorbs substances (e.g., intestinal epithelial cells).

Connective Tissue

• Main function: Binding and supporting other tissues.
• Rich in extracellular matrix with fewer cells, providing structural integrity.
• Consists of protein fibers and ground substance.

Connective Tissue Matrix - Protein Fibers

• Collagen Fibers: Strong and flexible fibers resistant to pulling forces.
• Elastic Fibers: Smaller fibers enabling recoil and flexibility, made of elastin.
• Reticular Fibers: Support blood vessel walls, composed of collagen with glycoprotein covering.

Functions of Connective Tissue

• Enclosing and separating tissues.
• Connecting different tissues (e.g., ligaments and tendons).
• Supporting and moving structures (e.g., bones and cartilage).
• Storing energy (e.g., adipose tissue and bones).
• Cushioning and insulating (e.g., adipose tissue).
• Transporting substances (e.g., blood).
• Protecting organs (e.g., bones and blood).

Connective Tissue Cells

• Fibroblasts: Large, flat cells with branches that produce fibers and migrate throughout the connective tissue.