Epithelium, Summaries of Anatomy

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Epithelium

Dr. Archana Rani Associate Professor Department of Anatomy KGMU UP, Lucknow

13.11.

EPITHELIAL TISSUE or EPITHELIUM

• The basic tissue of the body.
• Cells are arranged as continuous sheets.
• Single or multiple layers.
• Cells are held tightly together by cell junctions.
• Free surface
• Basal surface adheres to basal lamina or basement

membrane.

• Avascular but supplied by nerves.
• Has high capability to regenerate.

Functions

• Protection
• Absorption
• Barrier
• Excretion
• Secretory
• Function as sensory surfaces

Classification

According to shape, arrangement and the

specialization of their free surface:

• Simple

• Stratified

• Pseudostratified

• Transitional

Simple Squamous Epithelium

• Single layered
• Flat cells
• On surface view, like

floor tiles

• Elevated nuclei
• Examples:
  • Lung alveoli
  • Parietal layer of Bowman’s capsule of kidney
  • Inner aspect of tympanic membrane
  • Mesothelium
  • Endothelium

Basement membrane

Squamous cell

Nucleus

Function: Rapid transport of substances, secretion of fluid, diffusion of gases and osmosis

Simple Squamous Epithelium

Simple Cuboidal Epithelium

Simple Columnar Epithelium

• Cells having more height than width
• Nuclei are elongated, located in the lower half of cells
• Cells may show some surface modifications
• Examples:
  • GIT(stomach to anus)
  • Gall bladder
  • Uterine tube & cavity
  • Central canal of spinal cord

Function: Secretion and absorption; Ciliary action

Stratified epithelium

Stratified squamous (keratinized)

Stratified squamous (non keratinized)