Digestion is the physical and chemical process that breaks down foods ingested in the diet in their fundamental constituents making them absorbable by the body.
This process begins in the mouth by the fragmentation wrought by the teeth (chewing) and the first contact with digestive enzymes, amylase present in saliva.
At this stage you also have the first disinfection of food made by the ever present secretory immunoglobulin A in saliva.
The chewed food, hydrated and softened by the saliva into its two fluid and mucus components and "sprayed" by digestive enzymes and antibodies is called "cud" and begins its journey through the long (up to 11 meters) digestive tract whose first part is represented by the esophagus. This muscular canal that goes from the mouth to the stomach does not have an active role in digestion but it is necessary to transport the bolus through the chest. Posteriorly reaching the trachea, it crosses the diaphragm and ends in the stomach at the level of the cardia, a valve muscle (sphincter) that only opens to let the bolus pass closing immediately after, thus preventing the reflux of gastric juices ...
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http://www.natural1.it/nutraceutica/item/1410-alimentazione-e-patologie-gastriche
