Scientists Say: Exocytosis

Exocytosis (noun, “EX-oh-sy-TOH-sis”)

This is the process that cells use to dump something outside of their outer wall. First, the material to be removed is engulfed in a membrane within the cell’s interior. This bit of membrane forms a sac called a vesicle. That sac then travels to the outer edge of the cell. There, the sac’s outer membrane fuses with the cell’s membrane. Then the outside surface of this vesicle opens, releasing its contents to the outside world. This isn’t just for trash removal, cells have another system for that. Instead, exocytosis can be used to send messages or transport cell products.

In a sentence

Brain cells use exocytosis to dump chemical messengers that will serve as a message to some neighboring cell .

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Power Words

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cell   The smallest structural and functional unit of an organism. Typically too small to see with the naked eye, it consists of watery fluid surrounded by a membrane or wall. Animals are made of anywhere from thousands to trillions of cells, depending on their size. Some organisms, such as yeasts, molds, bacteria and some algae, are composed of only one cell.

cell membrane    Separates the inside of a cell from the outside of it. Some particles are permitted to pass through the membrane.

exocytosis  The process of vesicles fusing with the cell membrane to dump their contents outside of the cell.

vesicles    A small fluid- or air-filled sac within the body. They can reside within cells or outside of them.