2) The Levels of Structural Organization

There are SIX levels: the chemical level, cellular level, tissue level, organ level, organ system level and organismal level.
At a CHEMICAL LEVEL atoms full of matter combine with molecules that associate in specific ways to form organelles which are basic components of microscopic cells.
At a CELLULAR LEVEL the cells preform common functions but vary in shape and size, reflecting there unique functions of the body. These cells come together to create tissues.
At a TISSUE LEVEL the groups of cells have a common function. There are FOUR basic types of tissue and they are: epithelium tissue, muscle tissue, connective tissue and nervous tissue. Epithelium tissue covers the body surface and lines its cavities, muscle tissue provides movement, connective tissue supports and protects body organs and lastly, nervous tissue provides a means of rapid internal communication by transmitting electrical impulses.
At a ORGAN LEVEL a structure is composed of at least two tissue types that preforms a specific function of the body.
At a ORGAN SYSTEM LEVEL extremely complex functions become possible at this level. Each organ of the body has a specialized functional center that is responsible for the necessary activity that no other organ can preform.
At a ORGANISMAL LEVEL organs work together to accomplish a common purpose or goal.