Digestion transforms food into nutrients that can be used by the body. Through the process, food, alcohol, and medications are also detoxified. Along with nutrients, excess fluids are also absorbed and wastes are eliminated. Some of the major organs involved in the process of digestion in humans include the mouth, esophagus, stomach, small intestine, large intestine, and rectum.
The process of digestion begins it the mouth. It holds the food, and the teeth and tongue start the mechanical process of digestion, also known as mastication. Different teeth shapes enable them to bite and grind pieces of food. The salivary glands release salivary amylase, which starts the chemical process of digestion for carbohydrates.
Several structures aren’t directly involved in the process of digestion but are important in moving food to organs that are. For example, a cavity at the back of the mouth, the pharynx, holds structures that control swallowing. Swallowing moves the chewed food, or bolus, from the mouth to the esophagus while helping to prevent food from entering the wind pipe.
Another structure that moves food is the esophagus. It is a tube that extends from the pharynx to the stomach. The lower end has a sphincter, which is a group of special muscles. This esophageal sphincter prevents contents in the stomach from entering back into the esophagus.
The stomach plays an important part in digestion. It secretes gastric juices, one of which is pepsin. Pepsin aids in the chemical digestion of proteins. The process of digestion in the stomach includes using its muscles to mix and move the partially digested food, called chyme, through the pyloric sphincter to the duodenum of the small intestine.
When chyme is in the small intestine, the pancreas and the gallbladder secrete substances that aid the process of digestion. These substances further breakdown the chyme. Most nutrients are absorbed by the small intestine. The liver further breaks down and detoxifies nutrients, alcohol, and some medications passed to it by the small intestine. Along with these functions, the liver also produces bile, which is stored in the gallbladder to be released to the small intestine.
After the small intestine has completed its role in the process of digestion, its contents are passed to the large intestine, which serves as a container for the contents. In addition, the large intestine helps maintain the body’s fluid balance by absorbing water and electrolytes that may be present as well as forming feces. The rectum is in control of eliminating feces, which then passes out of the body through the anus.