Extrazellulärraum

Extrazellulärraum, also known as the extracellular space or interstitial space, refers to all the space outside of cells within a multicellular organism. It comprises the fluid-filled areas between cells and the structural components that support them. This space is not simply empty but is filled with a complex mixture of water, ions, small molecules, and large macromolecules like proteins.

The extracellular space plays a critical role in cell-to-cell communication and the transport of nutrients and waste products. Cells exchange substances with this fluid environment, which in turn is connected to the bloodstream and lymphatic system for broader distribution and removal. The composition of extracellular fluid is tightly regulated, maintaining specific concentrations of ions and molecules essential for cellular function and overall homeostasis. For example, the concentration of sodium, potassium, and calcium ions in the extracellular fluid is crucial for nerve impulse transmission and muscle contraction.

Major components of the extracellular space include the interstitial fluid, which bathes most cells; blood plasma, the fluid component of blood; and lymph, the fluid found within the lymphatic system. Structural elements like collagen and elastin fibers also reside in the extracellular space, providing mechanical support and tensile strength to tissues and organs. The extracellular matrix, a network of these structural proteins and other molecules, defines the physical properties and organization of tissues. Disruptions in the extracellular space and its composition can lead to various pathological conditions.