A cell is a fundamental anatomical unit, generally microscopic, of all the organisms alive, consisting of cytoplasm, one or more cores and a membrane that surrounds it. Its name comes from the Latin word "cellula".

  The nucleus. It determines that there are two types of cells: the eukaryote cells, that have a nucleus separated from the cytoplasm, and the prokaryotic cells where the different elements that compose it are mixed in the cytoplasm.

 The cytoplasm. - places between the membrane and the nucleus. It develops three fundamental functions in the cell:

          § Structural Function: it gives form to the cell and controls his movements.

          § Nourishing Function: it transforms the substances that it receives by means of the blood             in energy.

          § Function of storage: he guards substances of reservation.

  The membrane. - is semipermeable, dynamic and with aptitude to be modified, that is to say, it is possible to cross, can move and to change. It is formed by two substances: lipids and proteins. The membrane develops the following functions: Function to isolate and protect to the cell of the exterior. The membrana celular is the external part of the cell that wraps the cytoplasm. It allows the exchange between the cell and the way that surrounds it. He exchanges water, gases and nutrients, and eliminates elements of waste. 

- The Mitochondria: They are a part of the animal, entrusted to supply most of the energy necessary for the cellular activity. They are the head  of energy of the cell.

- Golgi's device - forms a part of the membranous cellular system. It is formed by a structure of smoothed sacks or cisterns (dictiosoma) accompanied of bladders of secretion. It places next the core and in animal cells surrounding the centriolo. The functions of the Ap. Of Golgi they are diverse: organizer plays a role inside the cell, takes part in the transport, ripeness, classification and distribution of proteins. 

The cellular centrosoma is exclusive of the animal cells. It is next the nucleus and is considered to be an organizing center. His function is to organize. From him structures of movement stem as cilios and scourges and it forms the achromatic spindle that facilitates the separation of the cromátidas in the mitosis. 

The reticulum endoplasmatic is a membranous system which structure consists of a network of  smoothed or cisterns, sáculos globular or bladders and túbulos sinuous that spread over the whole cytoplasm and report with the nuclear external membrane. Inside these smoothed sacks a space exists so called lúmen that stores the substances.