What triggers regulated secretion in cells?

Regulated secretion in cells is primarily triggered by signal-induced responses. This process involves the release of specific substances (such as hormones, neurotransmitters, or enzymes) in response to external signals, which can include hormones, neurotransmitters, or other types of chemical signals. When a cell receives these signals, various intracellular pathways are activated, leading to the fusion of secretory vesicles with the plasma membrane and the subsequent release of their contents into the extracellular space.

This mechanism allows cells to control their secretion precisely and respond to changing physiological conditions, ensuring that substances are released only when needed. In contrast, continuous cellular processes tend to involve ongoing functions that do not specifically trigger secretion. Passive diffusion involves movement of molecules across membranes without energy input and does not relate to controlled secretion. Random internal signaling lacks the specificity and organization that characterize regulated secretion mechanisms.