CELLS

The cells are the basic structural units of the body. There are many types of cells, each with its size and shape characteristic. Some, such as skeletal muscle, are large and can span across 30 cm. muscle, with a diameter of up to 100 um. These two types of cells represent only some of which are evident during differentiation.

The figure illustrates the structure of a typical cell of mammals, which shows that all of them are bounded by a cell membrane, also known as plasma membrane or plasmalema. The plasma membrane is a continuous sheet that separates the aqueous medium inside the cell cytoplasm, outside the cell, where it is the extracellular fluid. The form of a single cell is maintained through a series of strands of protein known as cytoskeleton.

At some point in their life cycle all cells possess a prominent structure, the nucleus, which contains the genetic material or DNA. Most cells only have a nucleus, but skeletal muscle cells show multiple cores because they come from the merger of a large number of progenitor cells called mioblastos. By contrast, the red cells from the blood loses its nucleus when ripe. The cells have structures that carry out specific functions, such as energy production, protein synthesis and secretion of various materials. The internal structures of a cell known as organelles, and include the nucleus, mitochondria, the endoplasmic reticulum, the Golgi apparatus and various vesicles coupled with the membrane.

Organization of the human organism

The basic components of the body are cells, which are grouped forming tissues. The main tissue types are:

* Connective tissue.
* Epithelial tissue
* Lymphoid tissue
* Tissue nervous
* Muscle tissue
* Tissue blood.

Each with their own characteristics:

* The connective tissues have a relatively small number of cells involved in an extensive extracellular matrix.
* In the smooth muscle have an abundant array acelular.
* The nervous tissue contains neurons (of which there are different types) and glliales cells.