Which term describes the environment outside a cell?

• A. Endocrine
• B. Intracellular
• C. Extracellular
• D. Paracrine

Answer: (C)

The environment outside a cell is called the extracellular environment. This term distinguishes what’s outside the cell from the interior, which is the intracellular space. The extracellular space includes things like interstitial fluid and the extracellular matrix that surround and support cells. Endocrine describes hormonal signaling through the bloodstream to distant sites, while paracrine describes signaling to nearby cells; these terms refer to communication, not the actual location of the environment. So, the best descriptor for the environment outside a cell is extracellular.