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Which Structures Break Down Food & Release Energy?

The human digestive system consists of a series of organs that slowly change food and drinks into usable energy, or molecules. Many structures contribute to the breakdown of food, from the mouth's salivary glands to the small intestine's wall construction. The body relies on the food's released energy for critical cellular functions.

  1. Digestive System Components

    • As food enters the mouth, it is initially broken down by the teeth and saliva. The food moves down the esophagus to the stomach. After mixing with the stomach acids, the food moves into the small intestine and the large intestine. All the unused waste expels out the anus at the end of the digestive system.

    Mouth and Stomach Functions

    • The saliva within the mouth breaks the large food portions into small pieces for faster chemical absorption. Polysaccharides, or starches, are broken into maltose molecules, a simpler particle structure for absorption within the body. Gastric juices mix with the food, and ready the mixture for movement into the small intestine, once the fragmented food particles reach the stomach. The gastric juices consist of strong hydrochloric acid.

    Small Intestine Functions

    • The main structure that absorbs the broken down food is the small intestine. Its internal surface consists of multiple folds down its length, housing small villi protrusions. The villi create a large surface area for capturing and releasing nutrients into the bloodstream. The bloo stream moves the nutrients to the rest of the body's cells, supplying the necessary energy for human life.

    The Digestive System's Organ Helpers

    • The pancreas and liver work alongside the tubular digestive system, contributing critically needed juices for molecule processing. The pancreas offers enzymes that process carbohydrates, fats, and proteins within the small intestine. The liver produces a fluid called bile. Bile is an important intestinal juice that breaks down fatty molecules, much like a grease-fighting dish detergent. The smaller fat molecules are easily absorbed by the small intestine afterward.

    Vitamins

    • Vitamins are also important nutrients requiring digestion and movement throughout the body. Fat-soluble vitamins, like vitamins A, D, E, and K, move through the small intestine's mucous membrane to the liver. The liver and surrounding fatty tissue store the vitamins. Vitamins B and C, soluble in water, are difficult to store. Any excess B and C vitamins excrete through the person's urine.

    Hormones

    • The absorbing structures use hormone controls for regulating the overall digestive process. Gastrin activates the stomach acids. Secretin and CCK initiate the pancreas' functions by moving digestive juices into the small intestine body.

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