Characteristics and Functions of Epithelial Tissue

Characteristics of Epithelial Tissue

• Covers the body's internal and external surfaces
• Lines cavities, glands, and organs
• Forms the lining of blood vessels and lungs
• Composed of tightly packed cells with little intercellular substance

Functions of Epithelial Tissue

• Protection: prevents water loss, regulates what enters/leaves the body
• Absorption: nutrients, gases, and ions
• Secretion: hormones, enzymes, and other substances
• Excretion: waste removal
• Sensation: detects light, sound, touch, taste, and smell

Types of Epithelial Tissue

• Simple Epithelium
  • Single layer of cells
  • Lines blood vessels, lungs, and kidney tubules
• Stratified Epithelium
  • Multiple layers of cells
  • Found in skin, mouth, and vagina
• Pseudostratified Epithelium
  • Single layer of cells, but appears stratified due to varying cell heights
  • Lines respiratory tract and some glands
• Cuboidal Epithelium
  • Cube-shaped cells
  • Found in kidneys, thyroid, and adrenal glands
• Columnar Epithelium
  • Elongated cells
  • Lines digestive tract and some glands
• Squamous Epithelium
  • Flat cells
  • Found in skin, lungs, and blood vessels

Specialized Epithelial Cells

• Goblet cells: produce mucus
• Cilia cells: have hair-like structures for movement
• Microvilli cells: have small projections for absorption
• Stereocilia cells: have long, non-motile projections for sensory function

Epithelial Tissue Characteristics

• Epithelial tissue covers the body's internal and external surfaces, including cavities, glands, and organs.
• It forms the lining of blood vessels and lungs.
• The tissue is composed of tightly packed cells with little intercellular substance.

Epithelial Tissue Functions

• Provides protection by preventing water loss and regulating what enters and leaves the body.
• Facilitates absorption of nutrients, gases, and ions.
• Enables secretion of hormones, enzymes, and other substances.
• Performs excretion by removing waste products.
• Detects light, sound, touch, taste, and smell through sensation.

Types of Epithelial Tissue

Simple Epithelium

• Consists of a single layer of cells.
• Lines blood vessels, lungs, and kidney tubules.

Stratified Epithelium

• Composed of multiple layers of cells.
• Found in skin, mouth, and vagina.

Pseudostratified Epithelium

• Appears stratified due to varying cell heights, but is a single layer of cells.
• Lines the respiratory tract and some glands.

Cuboidal Epithelium

• Cells are cube-shaped.
• Found in kidneys, thyroid, and adrenal glands.

Columnar Epithelium

• Cells are elongated.
• Lines the digestive tract and some glands.

Squamous Epithelium

• Cells are flat.
• Found in skin, lungs, and blood vessels.

Specialized Epithelial Cells

• Goblet cells: produce mucus.
• Cilia cells: have hair-like structures for movement.
• Microvilli cells: have small projections for absorption.
• Stereocilia cells: have long, non-motile projections for sensory function.