Epithelial Tissues and Cornea - Vocabulary Flashcards

Vocabulary flashcards covering key epithelial tissue concepts from the lecture notes, including basement membrane components, cell junctions, epithelial cell types, and corneal endothelium.

Epithelial tissue

Sheets of cells lining internal or external surfaces; forms a barrier between compartments; undergoes rapid renewal.

Basement membrane

Thin extracellular matrix that attaches epithelial/endothelial cells to connective tissue; separates epithelium from underlying tissue; bi-layered with lamina lucida and lamina densa.

Lamina lucida

Clear layer of the basement membrane adjacent to epithelial cells; part of the basal membrane.

Lamina densa

Dense layer of the basement membrane providing structural support; underlies lamina lucida.

Keratin

Intermediate filament protein expressed by epithelial cells; forms the cytoskeleton and anchors desmosomes and hemidesmosomes.

Tight junction

Apical cell junction that seals intercellular space and regulates paracellular transport.

Adherens junction (adhesive belt)

Cell–cell junction near the apical region that links to the actin cytoskeleton and strengthens adhesion.

Desmosome

Anchoring junction between epithelial cells that connects intermediate filaments for mechanical strength.

Gap junction

Intercellular channel allowing direct passage of ions and small molecules between neighboring cells.

Polarity

Organization of epithelial cells into distinct apical, basal, and lateral domains.

Apical surface

Cell surface exposed to lumen or external environment.

Basal surface

Cell surface attached to the basement membrane.

Lateral surface

Cell surfaces contacting neighboring epithelial cells.

Microvilli

Finger-like apical projections that increase surface area for absorption.

Cilia

Hair-like apical projections that move substances over the cell surface.

Endothelium

Simple squamous epithelium lining blood and lymphatic vessels.

Mesothelium

Simple squamous epithelium lining serous membranes (pleura, peritoneum, pericardium).

Simple squamous epithelium

One cell layer of flat cells; facilitates diffusion and filtration; lines endothelium, mesothelium, and kidney loop.

Simple cuboidal epithelium

One cell layer of cube-shaped cells; secretion and absorption; found in kidney tubules, glands, and ducts.

Simple columnar epithelium

One cell layer of tall cells; absorption and secretion; lines most of the GI tract, gallbladder, stomach.

Simple columnar epithelium with cilia

Columnar epithelium bearing apical cilia; conducts/transport materials; found in female reproductive tract and bronchi.

Pseudostratified columnar epithelium

Appears multi-layered due to nuclei at different levels; often ciliated; lines respiratory tract.

Stratified squamous epithelium

Two or more cell layers; protective; may be keratinized or nonkeratinized.

Keratinized stratified squamous epithelium

Stratified squamous with surface keratinized cells lacking nuclei (e.g., epidermis).

Nonkeratinized stratified squamous epithelium

Stratified squamous with living surface cells (e.g., mouth, esophagus, vagina).

Stratified cuboidal epithelium

Multiple layers of cuboidal cells; functions in transport and secretion; found in ducts of sweat and salivary glands.

Stratified columnar epithelium

Stratified epithelium with columnar cells; found in conjunctiva and some large ducts.

Transitional epithelium

Stratified epithelium that transitions from cuboidal to squamous with distension; lines urinary tract.

Corneal endothelium

Hexagonal simple epithelium on the cornea; regulates transport and hydration of the avascular cornea.

Bullous Keratopathy (BK)

Corneal edema and clouding due to failure of corneal endothelium to dehydrate the stroma; secondary bullae and pain; treated with dehydration, IOP reduction, or corneal transplant.

Fuchs endothelial dystrophy

Common corneal endothelial dystrophy causing endothelial dysfunction and edema.

EBMD (Epithelial Basement Membrane Dystrophy)

Disorder of the epithelial basement membrane leading to recurrent epithelial erosions.

Recurrent Corneal Erosion (RCE)

Repeated breakdown and erosion of corneal epithelium, often due to basement membrane abnormalities.

Basement membrane thickness variation

Thickness and permeability of the basement membrane vary by location and disease (e.g., diabetes, hypertension).

Epithelial tissue functions

Barrier/protection; absorption/diffusion; transport; secretion of hormones, enzymes, mucous.