Epithelial Tissue Quiz

Epithelial Tissue

• Epithelial tissue forms a protective layer covering body surfaces and lining internal surfaces of cavities, tubes, and organs.
• Epithelial cells are tightly packed together.
• They rest on a basement membrane.
• They lack capillaries and obtain nutrients from nearby capillaries.
• Surface cells are continuously replaced due to wear and tear via mitosis.

Learning Outcomes

• Students will be able to define epithelial tissue and list its functions.
• Students will be able to classify and describe epithelial tissue, providing examples of their distribution regarding function.

Functions of Epithelial Tissue

• Protection: Prevents mechanical abrasion, chemical injury, and bacterial invasion.
• Absorption: Absorbs nutrients and ions.
• Filtration: Allows the passage of solutes with specific sizes.
• Secretion: Secretes enzymes, hormones, and mucous.
• Sensory Reception: Receives external stimuli.

Basement Membrane

• A thin, delicate membrane.
• Composed of protein fibers and mucopolysaccharides.
• Separates the epithelium from the underlying tissue.

Classification of Epithelium

• Structurally and functionally divided into:
  • Covering epithelium: Covers body surfaces or lines body cavities.
    • External surface: Epidermis of the skin.
    • Internal surface: Body cavities (peritoneal, pericardial, and pleural cavities), tracts/tubes (digestive, respiratory, blood vessels).
  • Glandular epithelium: Specialized cells that produce secretions.

Classification of Covering Epithelia

• Based on the number of cell layers:
  • Simple: One layer of cells.
  • Stratified: More than one layer of cells.
  • Pseudostratified: Appears multilayered but all cells contact the basement membrane.
• Based on cell shape:
  • Squamous: Flat, scale-like cells.
  • Cuboidal: Cells are about equal in height and width.
  • Columnar: Taller than wide cells.

Simple Epithelium Types

• Simple squamous
• Simple columnar
• Simple cuboidal
• Pseudostratified

Simple Squamous Epithelium

• Single layer of flattened cells.
• Locations: Kidney glomeruli, air sacs of lungs, lining of heart, blood vessels, and ventral body cavities.
• Functions: Allows passage of materials by diffusion and filtration, secretes lubricating substances in body cavities.

Simple Cuboidal Epithelium

• Single layer of cube-like cells with rounded nuclei.
• Locations: Kidney tubules, ducts and secretory portions of small glands, and ovary surface.
• Functions: Absorption and secretion.

Simple Columnar Epithelium

• Single layer of tall, column-like cells with oval nuclei.
• Locations: Intestines, gall bladder, and uterine tube.
• Functions: Absorption and secretion.

Pseudostratified Columnar Epithelium

• Appears multilayered but all cells rest on the basement membrane, cells are tall and short with nuclei at different levels.
• Locations: Respiratory tract, epididymis, and ductus deferens.
• Functions: Absorption and secretion.

Stratified Epithelium Types

• Keratinized stratified squamous
• Non-keratinized stratified squamous
• Stratified cuboidal
• Stratified columnar
• Transitional

Stratified Squamous Epithelium

• 2 types: Keratinized and non-keratinized.
• Keratinized: Skin (dead, keratinized cells at the surface).
• Non-keratinized: Mouth, anus, vagina, esophagus (living, nucleated cells at the surface).
• Function: Protection from physical abrasion and chemical injury.

Stratified Cuboidal Epithelium

• Rare
• Locations: Ducts of sweat glands, mammary glands, and salivary glands.
• Function: Protection.

Stratified Columnar Epithelium

• Rare
• Locations: Large ducts of exocrine organs, male urethra.
• Functions: Protection and secretion.

Transitional Epithelium

• Special epithelium, number of cell layers change according to organ's state.
• Surface cells are large and binucleated.
• Locations: Urinary bladder and parts of the urinary tract.
• Function: Allows distension and prevents absorption of toxic substances in urine.

Specialization of Epithelial Cell Surfaces

• Microvilli: Finger-like projections increasing cell surface area for absorption (intestine, kidney).
• Cilia: Hair-like structures; motile.
• Stereocilia: Bundles of actin filaments; non-motile.
• Flagella: Movement.

Test your knowledge on various types of epithelial tissues, their locations, and functions. This quiz covers both simple and stratified epithelium, including specialized structures and characteristics. Perfect for students studying anatomy and physiology.