Epithelial Cells & Basic Histology

Vocabulary flashcards summarizing key terms and definitions related to epithelial cell structure, classification, junctions, surface specializations, secretory adaptations, and gland types covered in the lecture notes.

Histology

The microscopic study of body tissues and cells.

Cell

The basic structural and functional unit of living organisms.

Tissue

A group of cells with similar structure and function.

Organ

Structure composed of multiple tissue types working together.

System

A set of organs functioning cooperatively (e.g., circulatory system).

Epithelial Tissue

One of the four basic tissues; forms coverings, linings, and glandular units.

Muscle Tissue

Basic tissue specialized for contraction and movement.

Nervous Tissue

Basic tissue specialized for signal transmission.

Connective Tissue

Basic tissue that supports, connects, or separates other tissues.

Epithelial Cells

Specialized cells arranged in sheets (epithelia) for absorption, secretion, and barrier functions.

Basement Membrane

Thin layer of connective tissue underlying epithelium, rich in type IV collagen.

Squamous Cell

Flat, plate-like epithelial cell.

Cuboidal Cell

Epithelial cell whose height and width are roughly equal.

Columnar Cell

Tall epithelial cell whose height exceeds width.

Simple Epithelium

Single layer of epithelial cells.

Stratified Epithelium

Two or more cell layers; only basal layer contacts basement membrane.

Pseudostratified Epithelium

Single cell layer appearing multilayered because nuclei lie at different levels.

Transitional Epithelium

Stratified epithelium of urinary tract capable of stretching; also called urothelium.

Simple Squamous Epithelium

Single layer of flat cells; forms mesothelium and endothelium.

Endothelium

Simple squamous lining of blood and lymphatic vessels.

Mesothelium

Simple squamous lining of pleural, pericardial, and peritoneal cavities.

Simple Cuboidal Epithelium

Single layer of cube-shaped cells; typical in kidney tubules.

Simple Columnar Epithelium

Single layer of tall cells; lines alimentary canal and uterus.

Ciliated Columnar Epithelium

Columnar cells with motile cilia; in uterine tubes, bronchi, and some nasal passages.

Stratified Squamous Epithelium

Multiple layers with flat surface cells; adapted for protection.

Keratinized Stratified Squamous

Surface cells dead and filled with keratin; forms epidermis.

Non-keratinized Stratified Squamous

Surface cells alive and moist; lines oral cavity, esophagus, vagina.

Pseudostratified Columnar Epithelium

Columnar cells with nuclei at various levels; often ciliated with goblet cells (e.g., trachea).

Tight (Occluding) Junction

Seals adjacent cells, prevents paracellular diffusion, defines cell polarity.

Desmosome (Macula Adherens)

Spot anchoring junction linking intermediate filaments of adjacent cells.

Zonula Adherens

Belt-like anchoring junction associated with actin filaments.

Hemidesmosome

Anchors epithelial cell basal domain to basement membrane.

Gap (Communicating) Junction

Connexon-composed channels permitting small molecule exchange between cells.

Microvillus

Finger-like membrane projection that increases apical surface area for absorption.

Basolateral Fold

Deep invagination of basal/lateral membrane in ion-transporting cells.

Membrane Plaque

Rigid apical membrane area of transitional epithelium resisting stretch.

Cilium

Motile 0.2 µm-diameter projection that moves fluid over epithelial surfaces.

Goblet Cell

Unicellular mucin-secreting gland found within some epithelia (e.g., gut, airways).

Serous Secretion

Thin, watery protein-rich product; typical of pancreas and parotid glands.

Mucous Secretion

Thick, viscous secretion rich in mucin glycoproteins.

Mixed (Seromucous) Gland

Gland containing both serous and mucous cells, e.g., submandibular gland.

Merocrine Secretion

Exocytosis of products with no loss of cytoplasm.

Apocrine Secretion

Release of product with apical cytoplasm pinch-off.

Holocrine Secretion

Whole cell disintegrates to release product (e.g., sebaceous gland).

Endocrine Secretion

Product released into bloodstream for distant signaling.

Straight Tubular Gland

Unbranched secretory tube opening to surface (e.g., intestinal crypts).

Coiled Tubular Gland

Secretory tube coiled in dermis; example: sweat gland.

Branched Gland

Secretory units branching from a duct; e.g., mammary gland.

Steroid-Secreting Epithelial Cell

Cell with abundant smooth ER producing steroid hormones (adrenal cortex, gonads).

Ion-Pumping Epithelial Cell

Cell rich in mitochondria and basolateral folds for active ion transport (kidney tubule).

Barrier Function of Epithelium

Protective role achieved via occluding junctions, keratinization, transitional plaques, and strong anchoring junctions.