Relating to very small structural units throughout the internal areas of the physical structure which are functionally integrated to perform infinite numbers of complex tasks that are necessary for life: Every anatomically little element is referred to as a cell and each one has an invisibly small bag containing a fluid material called cytoplasm, surrounded by an extracellular skin called the cell membrane.

The extracellular membrane of a cell consists of double layers of fatty materials and proteins that hold each one together.

Additional functions of the extracellular membranes involve the regulating of the passages of materials into and out of the cells which enable useful substances like nutrients and oxygen to enter them and waste materials like carbon dioxide and substances like hormones to leave them.