FIGURE 1.

Illustration of the different spatial scales of models involved in the representation of the gastrointestinal system. An anatomical torso geometry is represented at the broadest scale. An anatomical model of the human stomach is an example of the models at organ level, while at the tissue level, the different muscle layers and their cell types must be represented. At the cellular level, smooth muscle cells in the circular direction (SMC_CM) and interstitial cells of Cajal (ICC_MY) are shown. The intracellular calcium [Ca²⁺]_i signaling pathways in the Faville et al.² ICC model are illustrated as an example of subcellular level models. The Faville et al² ICC model states that [Ca²⁺]_i is modulated by a number of transmembrane Ca²⁺ specific ion channels, which include an inward Ca²⁺ (I_Ca), non-selective cation channel (I_SNCC), and Ca²⁺-ATPase (I_PM). In addition, [Ca²⁺]_i sequestration is also influenced at the subcellular level by the actions of the endoplasmic reticulum (ER) and mitochondria (MT).