Lecture on Simple Epithelium

Overview of Epithelial Tissue

• Epithelial tissue subdivided into:
  • Simple Epithelium: One layer of cells
  • Stratified Epithelium: Multiple layers of cells
• In simple epithelium, each cell touches the basement membrane.

Types of Simple Epithelium

Simple epithelium is categorized based on the shape of the cells:

1. Simple Squamous Epithelium

• Characteristics:
  • Flat cells
  • Look like "fried eggs"
• Functions:
  • Ideal for diffusion due to the thin layer
• Locations:
  • Lungs (gas exchange)
  • Kidneys (transport)
• Special Names:
  • Mesothelium: Lines serous membranes and secretes watery fluid.
  • Endothelium: Lines blood vessels and the heart.
• Associated Condition:
  • Mesothelioma: Cancer of mesothelial cells

2. Simple Cuboidal Epithelium

• Characteristics:
  • Cube-shaped (as tall as they are wide)
  • May have microvilli to increase surface area
• Functions:
  • Absorption
• Locations:
  • Kidneys
  • Certain glands (e.g., liver, thyroid)

3. Simple Columnar Epithelium

• Characteristics:
  • Taller than they are wide
  • Can have microvilli
  • Presence of goblet cells (produce mucus)
• Functions:
  • Absorption and secretion
• Locations:
  • Digestive system (stomach, small intestine, large intestine)

4. Pseudostratified Epithelium

• Characteristics:
  • All cells touch the basement membrane
  • Nuclei at different levels give appearance of stratification
  • Contains goblet cells and cilia
• Functions:
  • Mucus secretion
  • Moving particles via cilia
• Locations:
  • Respiratory system (moves dust and bacteria out of airways)

Summary

• Simple epithelium has one layer of cells; each type is distinguished by cell shape:
  • Squamous: Flat
  • Cuboidal: Cube-like
  • Columnar: Column-like
  • Pseudostratified: Appears stratified but is not

These notes provide an overview of the different types of simple epithelium, their structures, functions, and where they are commonly found in the body.