Cellular Junctions and Signaling

Flashcards covering cellular junctions (desmosomes, tight junctions, gap junctions) and various types of cellular communication and signaling mechanisms (paracrine, autocrine, hormonal, neurohormonal, signal transduction, first/secondary messengers).

Desmosomes

Intercellular junctions that provide strong adhesions between cells and are linked to the intermediate filament cytoskeleton, giving mechanical strength to tissues.

Tight junctions

Intercellular junctions that limit the passage of molecules and ions between cells and block the movement of membrane proteins between apical and basolateral cell surfaces, preserving special functions.

Gap junctions

Specialized intracellular connections that directly connect the cytoplasm of two cells, allowing molecules, ions, and electrical impulses to pass through a regulated gate.

Paracrine signaling

A form of cell-to-cell communication where a cell produces a signal to induce changes in nearby cells, altering their behavior.

Autocrine signaling

A form of cell signaling where a cell secretes a hormone or chemical messenger (autocrine agent) that binds to an autocrine receptor on that same cell, leading to internal changes.

Hormonal signaling

Recognition of a hormone by an associated cell membrane or intracellular protein, which then acts on the cell.

Neurohormonal signaling

Signaling involving a neurohormone, which is any hormone produced and released by neuroendocrine cells into the blood and then uptaken by a target cell.

Neurohormone

Any hormone produced and released by neuroendocrine cells into the blood, subsequently taken up by a cell.

Signal transduction

The transmission of a molecular signal from the outside to the inside environment of a cell, initiated by surface proteins, ensuring an appropriate cellular response.

First messenger

An extracellular molecule that conveys instructions to the cell's interior, initiating signal transduction.

Secondary messenger

An intracellular molecule that relays a signal received at the cell's surface to the internal surface of that cell, initiated by a first messenger.

Ion channel

A type of surface protein that can open or close to allow an influx or efflux of ions into a cell, serving as an example of signal transduction.

Ligand

A molecule that binds to a protein in the cell membrane, initiating a step-by-step process within the cell, often leading to a specific biochemical pathway.