Cell signaling

In living things, cells send and receive signals.^[1][2][3] Cell signaling is a fundamental property of all cellular life in prokaryotes and eukaryotes.^[4]

Signals that come from outside a cell (extracellular signals) may be physical agents like mechanical pressure, voltage, temperature, light, or chemical signals (e.g., small molecules, peptides, or gas). Cell signalling can occur over short or long distances. Signalling molecules can be released through passive or active transports, or even from cell damage.

Receptors play a key role in cell signaling as they are able to detect chemical signals or physical stimuli. Receptors are generally proteins on the cell surface or in the interior of the cell. Examples are the cytoplasm, organelles, and nucleus.