Epithelial Tissues and Body Membranes Flashcards

Vocabulary flashcards defining key structures, cell classifications, gland mechanisms, and body membranes from the epithelial tissues lecture.

Histology

The study of tissues.

Epithelial Tissue

A tissue type composed of one or more layers of closely packed cells with little to no extracellular matrix that covers body surfaces, lines body cavities, and forms the majority of glands.

Apical Surface

The surface of epithelial tissue exposed to the external environment or internal body space, which may feature microvilli or cilia.

Basal Surface

The surface where epithelium attaches to underlying connective tissue.

Basement Membrane

A three-layered barrier between epithelium and connective tissue composed of lamina lucida, lamina densa, and reticular lamina.

Neuroepithelium

A specialized epithelium housing cells responsible for sight, taste, smell, hearing, and equilibrium.

Simple Epithelium

Epithelium consisting of a single layer of cells where every cell is in direct contact with the basement membrane.

Stratified Epithelium

Epithelium composed of two or more layers of cells where only the basal layer contacts the basement membrane.

Pseudostratified Epithelium

A type of simple epithelium that appears layered because cell nuclei are distributed at different levels, though all cells attach to the basement membrane.

Squamous Cells

Flat, wide, irregular epithelial cells arranged like floor tiles with flat nuclei.

Cuboidal Cells

Epithelial cells that are about as tall as they are wide, with rounded edges and a centrally located spherical nucleus.

Columnar Cells

Slender epithelial cells taller than they are wide, containing an oval nucleus oriented lengthwise in the basal region.

Transitional Cells

Epithelial cells that change shape depending on stretch, appearing polyhedral when relaxed and flattened when stretched.

Endothelium

Simple squamous epithelium that lines blood and lymph vessel walls.

Mesothelium

Simple squamous epithelium that forms the serous membrane of body cavities.

Goblet Cells

Unicellular exocrine glands that secrete the glycoprotein mucin, which forms mucus when mixed with water.

Keratinized Stratified Squamous Epithelium

Epithelium where superficial layers consist of dead, nuclei-lacking cells filled with keratin, as found in the epidermis.

Nonkeratinized Stratified Squamous Epithelium

Epithelium lacking keratin where all cells remain alive with visible nuclei and are kept moist by secretions; lines the oral cavity, esophagus, vagina, and anus.

Endocrine Glands

Ductless glands that secrete hormones directly into the blood.

Exocrine Glands

Glands composed of invaginated epithelium in connective tissue that connect to an epithelial surface via a duct.

Acini

Clusters of cells in multicellular exocrine glands that produce secretions.

Merocrine Glands

Exocrine glands that package secretions into vesicles and release them by exocytosis, such as lacrimal and salivary glands.

Apocrine Glands

Exocrine glands where the apical membrane pinches off to release secretions, such as mammary and ceruminous glands.

Holocrine Glands

Exocrine glands whose secretions form from accumulated product inside cells that disintegrate completely, such as sebaceous glands.

Mucous Membranes

Body membranes that line compartments open to the external environment, consisting of an epithelial layer and an underlying connective tissue called lamina propria.

Lamina Propria

The underlying connective tissue component of a mucous membrane.

Serous Membranes

Body membranes composed of mesothelium that line cavities not open to the external environment and produce friction-reducing serous fluid.

Cutaneous Membrane

The skin, consisting of keratinized stratified squamous epithelium and underlying connective tissue.

Synovial Membrane

A body membrane lining select joints, composed of areolar connective tissue covered by squamous epithelial cells lacking a basement membrane.