Epithelial Tissue and Junctions - Vocabulary Flashcards

Vocabulary flashcards covering key terms related to epithelial tissue and junctions from Page 1 notes.

Adherens junctions

Transmembrane proteins form a belt-like structure around the cell and use actin filaments as anchoring points on the inner side of the plasma membrane to provide strong resistance to cell separation.

Gap junctions

Channels that allow direct communication between adjacent cells, permitting the passage of small molecules and ions; located at the junction between neighboring cells.

Epithelium (Epithelial Tissue)

Tightly packed cells with little to no space between them; avascular; covers surfaces and lines cavities; rests on a basement membrane.

Avascular

Having no blood vessels; epithelial tissue is avascular and is nourished by vessels in nearby connective tissue.

Desmosomes

Button-like junctions that use keratin intermediate filaments in epithelial cells (and desmin in cardiac muscle) as anchoring points to resist mechanical forces.

Hemidesmosomes

Anchor epithelial cells to the basement membrane; half-desmosome connecting cell to extracellular basement membrane, using keratin filaments on the cell side.

Basement membrane (basal lamina)

Thin extracellular layer between epithelium and connective tissue; dense with collagen and laminin; anchors epithelium to underlying tissue and separates epidermis from dermis.

Basal surface

The side of the cell that faces the basement membrane.

Apical surface

The surface of the cell that faces away from the basal surface, toward the lumen or external environment.

Lateral surface

The sides of a cell that contact neighboring cells.

Surface epithelium

Long sheets of cells that cover surfaces and line surfaces; classified by shape and number of cell layers.

Glandular epithelium

Cells that make up the secreting portion of a gland.

Squamous epithelium

Shape: Flattened, thin cells (like fish scales).

Cuboidal epithelium

Shape: Cube-shaped cells.

Columnar epithelium

Shape: Tall, column-shaped cells.

Simple epithelium

Single layer of cells.

Stratified epithelium

Multiple layers of cells.

Pseudostratified epithelium

Looks like several cell layers but actually has one layer; all cells touch the basement membrane.

Transitional epithelium

Stratified, stretchable epithelium found in areas like the urinary bladder.

Simple squamous epithelium

One layer of flat cells; suitable for diffusion and filtration.

Simple cuboidal epithelium

One layer of cube-shaped cells.

Simple columnar epithelium

One layer of tall, column-shaped cells.

Stratified squamous epithelium

Multiple layers of flat cells.

Stratified cuboidal epithelium

Two or more layers of cube-shaped cells.

Stratified columnar epithelium

Multiple layers with the apical layer being columnar.

Pseudostratified columnar epithelium

Appears stratified but is a single layer; all cells contact the basement membrane.

Transitional epithelium (urothelium)

Stratified epithelium that can stretch, found in the urinary tract.