Digestive System

The Digestive System organs break down large food molecules into smaller ones where they are absorbed along with minerals and water into the body. Gastrointestinal tract (mouth, esophagus, stomach, small intestine, large intestine) and accessory organs (salivary glands, liver, pancreas) all work together.

Gastrointestinal tract

The mouth receives food and mechanically digests it (using the tongue and teeth), mixing it with saliva, which lubricate it and begin digestion. The pharynx is the passageway to the Respiratory System—food and breath both using the same path—and it leads to the esophagus, delivering food to the stomach.

The stomach secretes acids, digestive enzymes and gastric juices such as pepsin and hydrochloric acid to break down proteins, to send to the small intestine for the majority of the digestive process. The pancreas contributes enzymes and attempts to balance the pH by neutralizing acidity. The liver contributes bile (stored in the gall bladder), and also controls carbohydrate metabolism, converting some amino acids into energy. The liver also breaks down fatty acids to be processed in metabolism. In addition, the liver removes drugs and hormones from the blood, excreting them into the bile.

The large intestine is also referred to as the colon. The cecum connects the small to large intestine, where nondigested materials first travel up the ascending colon (right side of abdomen), across through the traverse colon (horizontally, across the top of the abdomen) where it then becomes the descending colon (left side of abdomen). At the bottom of its path, it becomes the sigmoid colon (S-shaped structure that descends downward toward the rectum). The functions of the large intestine are to reabsorb water, ions, vitamins and compact the waste material.