lec 3-Fundamentals of Physiology: Epithelial Cell Function

A collection of vocabulary flashcards covering the structural characteristics, polarity, specialized functions, and associated diseases of epithelial cells based on Dr. Kosha Mehta's lecture.

Epithelial cells

Cells that cover body surfaces, line body cavities, and form tissue in glands; they can be squamous, cuboidal, or columnar, and arranged in simple or stratified layers.

Endothelial cells

A special type of epithelial cells that specifically line the inner surfaces of blood vessels and lymph vessels.

Cell Polarity

A characteristic of epithelial cells where each surface (apical, lateral, and basal) has specialized morphology and distinct functional differences.

Glycocalyx

A carbohydrate coating of glycoproteins and glycolipids on the cell surface involved in cell-cell recognition, adhesion, and communication; in endothelial cells, it regulates vascular permeability.

Cilia

Motile cytoplasmic structures appearing as short, fine hair-like structures between $1-10\,\mu\text{m}$ in length, capable of moving particles and fluid along surfaces such as the trachea and uterine tube.

Microvilli

Irregular, closely packed projections of the cell membrane approximately $1\,\mu\text{m}$ in length that increase surface area for absorptive functions in the small intestine and kidneys.

Tight Junctions

Junctions that unite cells, such as Type I pneumocytes, and prevent the passing of material between cells to ensure selective absorption.

Desmosomes

Anchoring junctions found on the lateral domain of epithelial cells that help maintain tissue structural integrity.

Gap Junctions

Communication junctions on the lateral domain that allow for direct signaling or transport between adjacent cells.

Basal Domain

The part of the epithelial cell that serves as an adhesion interface with the extracellular matrix (ECM) and acts as a sieve or permeability barrier.

Cystic fibrosis

An autosomal recessive genetic disorder affecting the lungs and other systems, characterized by thick sticky mucus, frequent lung infections, and elevated sweat chloride levels.

CFTR (Cystic fibrosis transmembrane conductance regulator)

A transmembrane protein on the apical region of epithelial cells that transports ions and maintains salt-water balance via osmotic gradients; mutations lead to dehydrated, static mucus.

Cadherins

Transmembrane proteins, such as E-cadherin, that are major constituents of adherens junctions and are essential for mediating intercellular adhesion.

Contact inhibition

A process in normal cells where cell proliferation and growth cease once the cells come into contact with one another; this property is lost in malignant transformations.

Type I pneumocytes

Specialized epithelial cells that line $95\%$ of the alveoli and are responsible for gas exchange.

Type II pneumocytes

Cells in the lungs that produce a thin layer of surfactant to cover the alveolar surface.

Selective Reabsorption

A kidney process occurring in the proximal convoluted tubule where specific amounts of substances, such as $100\%$ of glucose and amino acids and $65\%$ of water and salts, are moved back into the bloodstream.

Pancreatic acinar cells

Exocrine cells of the pancreas that secrete digestive enzymes, ions, water, and high concentrations of $NaHCO_3$ into the duodenum.

Islets of Langerhans

The endocrine region of the pancreas containing Alpha and Beta cells; destruction of Beta cells results in Diabetes mellitus type 1.