In the previous study session III you have learnt about relevant cardiovascular physiology, the effects of anesthesia and methods of assessment on the cardiovascular system. This study session focuses on gastrointestinal system (GIS) physiology relevant to anesthesia. Extraction of water and nutrients from food and its absorption comprise the primary function of the gastrointestinal (GI) tract. The digested contents of the GI tract are absorbed by the intestinal mucosa into the portal circulation. Both chemical and physical factors are important in the digestion process. If food enters from the pharynx to air way the patient may obstruct or damage the alveolar tissue to cause hypoxia and cardiac arrest. Understanding the mechanisms of deglutition and the process of gastric emptying, as well as the role the liver in the metabolism of process is important. Therefore in this study session you will learn the anatomy and physiology gastrointestinal system relevant to anesthesia providers. In addition, methods of assessment and the effects of anesthesia and methods on the GIS will be addressed.