Final answer:
Exocytosis is the process where cells use vesicles to transport and release large molecules outside of the cell, important for several biological functions such as hormone and enzyme secretion.
Step-by-step explanation:
Movement of large signaling molecules out of the cell typically requires exocytosis. This process involves vesicles carrying substances that fuse with the plasma membrane, subsequently releasing the contents to the exterior of the cell. Exocytosis is essential for various functions, such as the secretion of digestive enzymes by the stomach and pancreas, hormones by endocrine cells, and neurotransmitters at synapses between neurons. Moreover, the expelled vesicle membrane becomes a part of the cell membrane.
Cells use vesicular transport for substances too large to pass through the plasma membrane directly. Exocytosis represents an active transport mechanism. For example, cells involved in immune responses employ regulated secretory pathways for substances like histamine, released in response to specific signals or events.