A Hierarchical Model
Level 0 Patient as a whole
Level -1 Major patient part (chest, head)
Level -2 Physiologic System (cardiovascular)
Level -3 System part or organ (heart)
Level -4 Organ part (bundle of His)
Level -5 Cell (myocardial cell)
Level -6 Cell part (mitochondria)
Level -7 Macromolecule (enzyme)
Level -8 Micromolecule (glucose)
Level -9 Atoms or ions (sodium, potassium)