Extracellular/Intracellular Materials and Cell Signaling - Vocabulary Flashcards

Vocabulary flashcards covering extracellular/intracellular materials, cell junctions, cell adhesion, and extracellular signaling pathways as presented in the notes.

Intracellular materials

Materials found within cells; includes cytoplasm, organelles, and inclusions (e.g., fat, hemoglobin, glycogen, keratin).

Extracellular materials

Materials found between cells or outside of cells; can lie in tissues or body cavities (e.g., saliva, serous fluid, synovial fluid). Also called intercellular material.

Interstital fluid

The fluid found between the cells of a tissue; part of the extracellular fluid.

Plasma

The extracellular fluid component of blood.

Matrix (extracellular matrix)

Proteins and polysaccharides secreted by cells that determine tissue properties; stabilizes tissue structure and regulates cell division, migration, proliferation, shape, and function.

Fibers

Structural proteins in the matrix—collagen, elastic, and reticular fibers.

Attachment proteins

Noncollagen proteins that organize matrix components and mediate cell–matrix and cell–cell attachments.

CAMs (Cell Adhesion Molecules)

Membrane proteins that mediate adhesion between cells and/or to the extracellular matrix.

Tight junctions

Cell junctions that seal adjacent cells to prevent paracellular movement of substances.

Desmosome

A strong cell–cell junction that uses cadherins and a cytoplasmic plaque of attachment proteins to link cells.

Cadherin

Calcium-dependent adhesion proteins that mediate cell–cell adhesion, especially in desmosomes.

Gap junction

Channels connecting adjacent cell cytoplasms to allow direct transfer of ions and small molecules.

Connexons

Protein channels that form gap junctions between neighboring cells.

Cell–Cell adhesion

Adhesion between cells mediated by membrane proteins and the extracellular matrix via CAMs.

Receptor

A protein that binds a specific ligand to elicit a cellular response.

Ligand

Signaling chemicals that bind to receptors.

Signaling cell

The cell that generates the signaling ligand.

Target cell

The cell that has the specific receptor for a given ligand.

Contact-dependent signaling

Signaling that requires direct contact between the signaling cell and the target cell.

Extracellular signaling

Signaling where soluble ligands are secreted and travel to target cells.

Hormone

A ligand secreted by endocrine glands that travels through the bloodstream to reach distant target cells.

Endocrine signaling

A signaling mode in which hormones (ligands) travel via the bloodstream to distant target cells.

Catalytic protein kinase receptor

A receptor with intrinsic catalytic activity that, upon ligand binding, activates signaling via phosphorylation.

Tyrosine kinase receptor

A receptor type whose kinase activity phosphorylates target proteins on tyrosine residues upon ligand binding.

Chemically gated ion channel

A receptor that forms a closed ion channel which opens when a ligand binds, allowing ion flow.

G protein–coupled receptor (GPCR)

A membrane receptor that, when bound by a ligand, activates a G protein to trigger intracellular signaling.

Second messenger

A small molecule produced by an effector enzyme (often via GPCR signaling) that amplifies the signal inside the cell (e.g., cAMP).

Effector protein

A protein activated by a G protein or receptor signaling that leads to production of a second messenger or direct cellular response.

GPCR signaling steps

1) Ligand binds receptor; 2) Receptor activates G protein; 3) G protein activates an effector enzyme; 4) Effector produces a second messenger; 5) Second messenger activates kinases.