Chemical Digestion in the Human Body, Essay Example

Defined as the mechanical and chemical breakdown of food into constituent absorbable substances required for human metabolism, chemical digestion involves what are known as digestive glands in the body, such as the salivary, gastric, intestinal, liver, and pancreatic which secrete important chemicals needed for breaking down food substances, such as hydrochloric acid (in the stomach), bile (in the liver), mucus (in the small intestines), and various types of enzymes (Glanze 371).

Protein is broken down in the stomach by gastric juices and what is known as pepsin, an enzyme that catalyzes the hydrolysis of protein in conjunction with hydrochloric acid. Technically, pepsin or pepsinogen is “secreted by pyloric and gastric chief cells and converted into the enzyme in an acidic environment” in the stomach (Glanze 898). Lipids, such as cholesterol, fatty acids, neutral fat, phospholipids, and triglycerides, are mostly digested in the small intestines and pass through the intestinal walls so as to enter the bloodstream where they are absorbed as energy reserves.  Carbohydrates or organic compounds like galactose, fructose, and glucose, are also mainly broken down in the small intestines and pass through the intestinal walls to enter the circulatory system via carbohydrate metabolism (Glanze 195).

Nucleic acids like DNA and RNA and composed of nucleotides are also mainly digested in the small intestine and assist the body with energy storage and release (Glanze 822). Also, the pancreas plays two major roles in digestion by producing “hormones and digestive juices that dump into the duodenum” and “sugar and growth regulating biochemicals that empty directly into the bloodstream” after being digested (Barron, “Pancreas and Digestion”). Of course, the salivary glands that excrete saliva play a major role in the digestion of food substances by helping to break them down in the mouth via chewing.

Bibliography

Barron, John. “Pancreas and Digestion.” 1995. Web. 26 July 2012. <http://www. jonbarron.org/enzymes/natural-health-newsletter-understanding-pancreas-digestion>

Glanze, Walter D. Mosby’s Medical and Human Anatomy Encyclopedia. St. Louis, MO: C.V. Mosby & Company, 2005.