The stomach as a system and the pathogenesis of experimental ulcer

The stomach is prone to ulceration because of the hostile environment that exists within its lumen. The most important etiologic factor remains a topic of debate. We have considered the stomach as a system to lend insight into which pathophysiologic mechanisms might be most important. Systems are described by their content, hierarchy, entropy and interactions. The states of health, disease and death (i.e. ulceration) are represented by progressively increasing levels of entropy. It is argued that many of the purported causes of ulcer disease, such as acid back-diffusion or alcohol related necrosis, represent alterations in the system that affect small groups of cells that are low in the hierarchy and cause the tissue to enter the diseased state. We hypothesize that because blood flow is high within the hierarchy it represents the major homeostatic mechanism. If blood flow responds appropriately the system may return to the healthy state. If it does not the death of the system results in ulceration. Experimental evidence to support these contentions is presented.