Levels of Structural Organization

Levels of Structural Organization

Terms and Nomenclature

Chemical Level: Simplest Level of the Structural Organization. Made up of atoms and molecules.

Organelles: Basic Components of the microscopic cells.

Cells: Smallest units of living things.

Cellular Level: Second Level of the Structural Organization. Made up of Cells.

Tissue Level: Third Level of the Structural Organization. Made up of Tissues (Four basic types: epithelium, muscle, connective tissue, and nervous tissue).

Tissues: groups of similar cells that have a common function.

Organ: Discrete structure composed of at least two tissue types (four is more common) that perform a specific function for the body.

Organ Level: Fourth Level of the Structural Organization. Made up of Organs and performs extremely complex functions.

Organ System Level: Fifth Level of the Structural Organization. Made up of multiple organs that work together to accomplish a common purpose. These are the "Organ Systems."

Organismal Level: Highest Level of Structural Organization. Represents the sum total of all structural levels working together to keep us alive.

Diagrams and Images