Digestive System Anatomy and Function: An Overview of the Digestive System

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Food enters the mouth, where it is broken down by the process of chewing. Saliva is added to the food, which lubricates the chewed food so it can enter the throat and esophagus more easily. Saliva also contains enzymes that help digest starches. Mouth problems such as abscesses, infections, and sores can make it difficult to chew and break down large food particles.


The esophagus connects to the mouth to the stomach, which allows chewed food to enter the stomach so digestion can begin. Acid reflux disease, also known as GERD, can disrupt the travel of food from this tube to the stomach. In this condition, stomach acid backs up into the esophagus, causing pain, belching, and a feeling of heartburn.


The stomach is the organ where digestion begins. Acids and enzymes present in the stomach break down proteins and other molecules. The remaining particles move from the stomach into the small intestine. Delayed gastric emptying is a condition that can affect the speed at which food empties from the stomach into the small intestine. Also called gastroparesis, this condition can cause nausea, vomiting, and abdominal discomfort.


The liver is responsible for metabolic processes in the human body. This is accomplished through the use of bile sites, which are sent to the small intestine so that fats can be broken down and absorbed.

Small Intestine

This is where the bulk of chemical digestion occurs, and it is also the organ that allows nutrients to be absorbed from foods. Enzymes in this organ allow for the breakdown of nutrients. Intestinal obstructions and other related conditions can interrupt the digestion process or prevent the absorption of nutrients from the small intestine. This can lead to malnutrition.

Large Intestine

Water is eliminated and feces is formed in the large intestine. This organ is also the site of bacterial fermentation.

Rectum and Anus

Solid feces is stored in the rectum and eliminated through the anus. If too much water is in the feces, this causes diarrhea. Diarrhea should be treated quickly to prevent dehydration and electrolyte imabalances.