Conference "The journey of a Ham and Salad sandwich

The prologue briefly describes the emergence of cellular life, drawing its nourishment directly from its environment, right up to the complex system of multi-cellular beings of which we are a part.
These beings require a highly elaborate feeding system to ensure their existence.
The purpose of this system is to recover food from the external environment and transform it to provide energy for the cells, enabling them to function and reproduce.
The digestion of a ham-butter-salad sandwich is approached as a 3-stage journey to describe the transformation and utilization of ingested food:

1- The zone of absorption: from the mouth to the stomach.

2-The assimilation zone: from the duodenum to the end of the small intestine.

3- The evacuation zone: the area where food is expelled from the body.

Various medical problems may arise at each stage, and these are discussed below.

In conclusion, 2 points should be emphasized:

The importance of the intestinal microbiota at every stage.

The harmful role of untimely intervention by the conscious brain in the functioning of the digestive system.