Topic 2: Cells and Tissues - Vocabulary Flashcards (Video)

Vocabulary flashcards covering extracellular environment, cell adhesion, cell signaling, tissues, epithelial tissue types, glands, and secretory mechanisms as presented in Topic 2 notes.

Extracellular environment

The fluid and matrix outside cells, including interstitial fluid, plasma, and the extracellular matrix, through which nutrients and signals move.

Interstitial fluid

Fluid in tissue spaces around cells; a component of the extracellular environment involved in exchange between blood and cells.

Plasma

The liquid component of blood in which blood cells are suspended; part of the extracellular environment.

Extracellular matrix

A network of proteins and polysaccharides outside cells that provides structural support and regulates cell behavior.

Cell adhesion molecules (CAMs)

Proteins on cell surfaces (e.g., cadherins, integrins) that mediate adhesion to other cells or to the extracellular matrix.

Tight junctions

Occluding junctions that seal gaps between adjacent epithelial cells, restricting paracellular transport.

Desmosomes

Strong cell–cell junctions that link intermediate filaments of adjacent cells to resist mechanical stress.

Gap junctions

Intercellular channels that allow direct chemical and electrical communication by passage of ions and small molecules.

Adherens junctions

Cell junctions that connect to the actin cytoskeleton and help maintain tissue structure.

Integrins

Transmembrane receptors that mediate cell–extracellular matrix adhesion and signaling.

Contact signaling

Communication between cells that requires direct membrane-to-membrane contact.

Chemical signaling

Communication via secreted molecules (hormones, paracrine/autocrine factors) that diffuse to target cells.

Electrical signaling

Communication via electrical impulses and ion flow, often through gap junctions.

Tissue

A group of cells with a common structure and function.

Histology

The study of tissues, including their structure, composition, and organization.

Four tissue categories

Epithelial, connective, muscle, and nervous tissues.

Epithelial tissue

A tissue that covers surfaces and lines cavities, is avascular, regenerates readily, and shows polarity.

Simple squamous epithelium

Single layer of flat cells; functions in diffusion/filtration; locations include air sacs, lining of vessels, and serous membranes.

Simple cuboidal epithelium

Single layer of cube-shaped cells; functions in absorption and secretion; locations in kidney tubules and glands.

Simple columnar epithelium

Single layer of tall, column-like cells; absorption and secretion; often with microvilli/goblet cells (stomach, intestines).

Pseudostratified columnar epithelium

Appears stratified but all cells contact the basement membrane; usually ciliated with goblet cells; lines the trachea and portions of the male reproductive tract.

Stratified squamous epithelium

Multiple cell layers; protects underlying tissues; keratinized in skin; non-keratinized in mouth, esophagus, and vagina.

Stratified cuboidal epithelium

Two or more layers of cube-shaped cells; typically found in ducts of glands.

Stratified columnar epithelium

Several cell layers with apical columnar cells; relatively rare; lines some large ducts.

Transitional epithelium

Stratified, stretchable epithelium; lines the urinary bladder and ureters.

Gland

A cell or organ that produces and releases substances for use elsewhere or for elimination.

Exocrine gland

Gland that secretes products into ducts leading to surfaces (skin or mucous membranes).

Endocrine gland

Gland that secretes hormones directly into the bloodstream without a duct.

Multicellular exocrine glands

Glands composed of many cells that form ducts; classified by structure (simple/compound; tubular/acinar) and secretory mechanism.

Merocrine secretion

Secretions released by exocytosis without loss of cytoplasm.

Apocrine secretion

Secretions involving the release of apical cytoplasm in vesicles.

Holocrine secretion

Secretions that release entire cells which disintegrate to release their products.