membrane

In science, a membrane is a thin layer of tissue that separates two parts of an organism. Membranes are found all over the body, including in cells, organs, and tissues.

Membranes are made up of molecules that are arranged in a specific way. This arrangement allows the membrane to be selective about what molecules can pass through it.

For example, the cell membrane is a barrier that separates the inside of the cell from the outside environment. The cell membrane allows some molecules, such as water and oxygen, to pass through it, but it prevents other molecules, such as bacteria, from entering the cell.

Membranes are important for many different functions in the body. They help to protect cells, transport molecules, and regulate the movement of fluids.

The cell membrane is a thin layer that surrounds the cell and controls what can enter and exit the cell.