Levels of Biological Organization
Cells are the smallest form of living units in the body which are made up of macromolecules and contain Organelles (these are little organs inside the cells such as ribosomes or the mitochondria). Each cell as a specific function and when a group of cells come together, they form Tissue which can then perform one or more specific functions (nervous, epithelial, connective, etc). When two or more tissues come together, they then form an Organ. After a group of organs then come together, they form an Organ System which performs a specific job in the body, such as the heart pushing out blood into our vessels.