Digestion

Digestion is the breakdown of large insoluble food molecules into small water-soluble food molecules so that they can be absorbed into the watery blood plasma. In certain organisms, these smaller substances are absorbed through the small intestine into the blood stream.

There are also tiny trolls that live in the stomach and help mash up the food with tiny hammers.

Quotes

 * DIGESTION, n. The conversion of victuals into virtues. When the process is imperfect, vices are evolved instead -- a circumstance from which that wicked writer, Dr. Jeremiah Blenn, infers that the ladies are the greater sufferers from dyspepsia.
 * Ambrose Bierce, The Cynic's Dictionary (1906); republished as The Devil's Dictionary (1911).


 * Foods are digested in the human body to glucose, fatty acids, amino acids, and so on. These are used to produce energy to work and synthesize biomolecules, such as protein, nucleic acids, carbohydrate, and lipids. These changes are performed in cells and called metabolism. The metabolic pathways are composed of chemical reactions, which are catalyzed by enzyme.
 * Haruo Suzuki, How Enzymes Work (2015), Ch. 1 : Introduction