What is the process called when a cell releases substances to the extracellular environment?

The process through which a cell releases substances to the extracellular environment is known as exocytosis. During this process, vesicles containing materials, such as proteins or neurotransmitters, fuse with the cell membrane and release their contents outside of the cell. This is crucial for various cellular functions, including signaling between cells, secretion of hormones, and disposal of waste products.

In contrast, endocytosis refers to the process of a cell taking substances in from outside its membrane, dissolution generally refers to the process of a substance being broken down in a solvent, and filtration involves the movement of fluids and solutes through a barrier due to pressure, which does not specifically involve the active release of substances by a cell. Thus, exocytosis precisely describes the mechanism of releasing materials into the extracellular space.