Endocytosis and Exocytosis

These are both methods of bulk transport. Bulk transport is the movement of solids or liquids.

There are two types of endocytosis: phagocytosis is the movement of solids – like cells or large proteins; pinocytosis is the movement of liquids.

In endocytosis the cell membrane extends around the particles being taken into the cell. Eventually the particles are surrounded and the membrane of the cell fuses around the particle, forming a vesicle in the cytoplasm containing the particle.

Exocytosis is the mechanism by which large particles such as enzymes and hormones are secreted from cells. The vesicle containing the particles migrates to the cell membrane and fuses with it, releasing the particles to the outside of the cell.