Epithelial Tissue Quiz

Overview of Epithelial Tissue

• Epithelial tissue consists of sheets of cells that cover surfaces and line cavities.
• Classified by stratification (layering) and morphology (shape).
• Separated from underlying connective tissue by a basement membrane, which consists of an upper acellular layer and an underlying collagen-rich layer.
• Most epithelia are avascular, relying on diffusion for nutrient delivery and waste removal.

Special Surface Modifications

• Motile cilia arise from basal bodies, found in respiratory and reproductive systems.
• Non-motile modifications include microvilli in the intestines and kidney, enhancing absorption.
• Junctional complex includes tight junctions (prevent material entry), adhering junctions (adhesion), and desmosomes (resistance to shearing stress).
• Hemidesmosomes attach cells to the basement membrane, while gap junctions facilitate cell communication.

Simple Squamous Epithelium

• Comprises a single layer of flat cells.
• Lines external surfaces of digestive organs, lungs, and heart, and inside heart chambers, blood, and lymph vessels.
• Functions include reducing friction, enabling passive transport, and facilitating secretion.

Simple Cuboidal Epithelium

• Composed of a single layer of cube-shaped cells with central nuclei.
• Lines small ducts of various organs and the apical surfaces of kidney tubules.
• Features microvilli that transport and process filtered materials.

Simple Columnar Epithelium

• Single layer of tall cells often with goblet cells for secretion.
• Covers digestive organs such as the stomach and intestines.
• Functions in secretion (mucus in the stomach) and absorption (in the intestines, aided by microvilli).

Stratified Epithelia

• Comprised of multiple cell layers; stratification determines subtype.
• Stratified squamous epithelia feature superficial cells (for protection), intermediate cells, and basal cells, with connective tissue extending beneath.
• Keratinized stratified squamous epithelium protects against abrasion, while non-keratinized forms a moist layer in areas like the mouth and esophagus.
• Stratified cuboidal epithelium protects larger ducts in glands.

Pseudostratified Columnar Epithelium

• All cells reach the basement membrane but not all extend to the surface.
• Contains ciliated cells, aiding in the movement of mucus and particles in the respiratory tract.
• In reproductive organs, transports and moves material across surfaces.

Transitional Epithelium

• Unique to the urinary system (bladder, ureters).
• Can change shape depending on organ distension—appearing domed when relaxed and flattened when stretched.
• Provides a barrier against urine while accommodating volume changes.

Additional Information

• Basement membrane supports and anchors epithelial cells to the underlying connective tissue.
• Modifications such as cilia and microvilli enhance the specific functional capacity of epithelial tissues.
• Stratified epithelial types adapt to different functional needs, influenced by their structure and location.

Test your knowledge of epithelial tissues with this comprehensive quiz based on Eroschenko's 'Atlas of Histology'. You will identify characteristics, classify tissues, and justify their locations in the body. Perfect for those studying histology and anatomy!