The smallest living unit of organization in the body is the cell, because each cell is capable of performing any necessary functions without the aid of other cells (Figures 1 and 2, Table 1). Each cell has a cell membrane, cytoplasm, organelles, and inclusions. Thus, every cell is a world unto itself (like a small gated city) surrounded by a boundary, having “factories” and other “industries” that make it almost self-sufficient