PHTH 7511: Human Anatomy I - Histology: Epithelium Flashcards

Comprehensive vocabulary flashcards covering epithelial tissue types, characteristics, functions, classifications, and surface specializations based on lecture notes.

Epithelial Tissue

One of the four basic tissues of the human body that forms the covering of all body surfaces, lines body cavities and hollow organs, and is the major tissue in glands.

Connective Tissue

One of the four basic tissues of the human body, distinct from epithelial, muscle, and nervous tissues.

Membrane epithelium

A sheet of cells which covers or lines an external or internal surface, existing in single or multi-layers.

Endothelium

A specialized epithelium that lines fully internal pathways, such as blood vessels.

Mesothelium

A specialized epithelium that lines body cavities, including the peritoneum, pleura, and pericardium.

Avascular

A characteristic of epithelial tissue meaning it lacks its own blood supply and is dependent upon diffusion for survival.

Basement membrane (Basal lamina)

A semipermeable barrier between the epithelium and its underlying connective tissue, formed by both tissue types.

Secretion

An active process of moving internally synthesized materials like hormones, enzymes, and saliva into the body for metabolism.

Excretion

A passive process of waste removal from the body, involving materials such as carbon dioxide, sweat, tears, faeces, and urine.

Absorption

The taking of materials into the cell or across tissues and internal organs, such as the intestine, liver, and lungs.

Filtration

The trapping and sequestering of particles from air or fluid to facilitate the eventual excretion of foreign bodies.

Diffusion

The passive transport of molecules from regions of higher concentration to regions of lower concentration.

Simple Epithelium

A classification of membrane epithelium consisting of a single layer of cells.

Stratified Epithelium

A classification of membrane epithelium consisting of more than one layer of cells.

Pseudostratified Epithelium

A single layer of cells appearing as multiple layers; every cell is attached to the basement membrane but not all reach the free surface.

Squamous

An epithelial cell shape characterized by being flat.

Cuboidal

An epithelial cell shape where cells are about as tall as they are wide.

Columnar

An epithelial cell shape where cells are taller than they are wide.

Simple Squamous Epithelium

A single layer of flattened cells found in the lining of blood vessels, peritoneal/pleural cavities, and lung alveoli.

Simple Cuboidal Epithelium

A single layer of square-ish cells with a centrally located nucleus, found in kidney tubules and gland ducts.

Simple Columnar Epithelium

A single layer of tall cells with basally located nuclei, found in the respiratory tract (ciliated) and GI tract (non-ciliated).

Keratinized Stratified Squamous Epithelium

Multiple layers of cells where surface cells are dead and filled with keratin; found in the skin, gingiva, and hard palate.

Non-keratinized Stratified Squamous Epithelium

Multiple layers of flattened surface cells primarily protecting against abrasion in the mouth, esophagus, and vagina.

Transitional Epithelium

A specialized epithelium with large, non-flat surface cells that are stretchy; located in the urinary system (bladder).

Microvilli

Non-motile, delicate fingerlike cytoplasmic projections about $1\,\mu m$ in length that increase surface area for absorption and diffusion.

Villi

Multicellular finger-like projections from membranous structures, typically $0.5$ to $1.6\,mm$ in length, that increase surface area.

Cilia

Large, motile projections containing microtubules that require ATP to move materials along the cell's free surface.

Tight junction (Zonula Occludens)

The uppermost component of the junctional complex that occludes extracellular space to prevent solute passage.

Adhering Junction (Zonula Adherens)

A lateral surface specialization that is not as tight as a tight junction, leaving some extracellular space present.

Desmosomes (Macula Adherens)

A spot junction resembling a 'dab' of glue that does not continue around the entire cell.

Gap Junction (Macula Communicans)

Aggregates of intercellular channels that permit direct cell-to-cell transfer of ions and small molecules.

Hemidesmosomes

Basal surface specializations that attach a single cell to the basement membrane using keratin monofilaments.

Exocrine glands

Glands that secrete or excrete products through a duct to an external or internal surface, such as salivary or sweat glands.

Endocrine glands

Ductless glands that secrete products (hormones) directly into the blood, such as the pituitary or thyroid glands.