The first step to obtaining nutrients from a hamburger meal is taking it by mouth and then breaking it with saliva and teeth. Subsequently, in order for nutrients, including protein, carbohydrate, and lipid, to be utilized for energy, the hamburger meal must undergo mechanical and chemical digestion (“Digestive System Processes,” n.d.). Thus, all of it is realized through three stages: digestion, absorption, and metabolism.
Carbohydrates in the mouth are broken down by amylase, an enzyme in saliva, into disaccharides and move along the esophagus, which produces mucus but not digestive enzymes for lubrication. Further, in the duodenum, they are broken down by pancreatic juice into monosaccharides (“Digestive System Processes,” n.d.). The monosaccharides are absorbed into the bloodstream while passing through the intestinal epithelium and move to various cells in order for use formed in the process of metabolism glucose to generate energy.
Most of the protein digestion process occurs in the stomach. In particular, at the first stage of protein passage through the digestive system, it splits into peptides with the enzyme pepsin’s help. In a second step in the duodenum, peptides are further broken down by other enzymes such as chymotrypsin, elastase, and trypsin (“Digestive System Processes,” n.d.). Finally, through the small intestine, the amino acids formed are absorbed into the bloodstream to be metabolized.
Lipid digestion begins with lingual lipase in the stomach; however, most of the digestion occurs in the small intestine via pancreatic lipase. When lipids enter the duodenum, bile is released owing to hormonal reactions. (“Digestive System Processes,” n.d.). Through emulsification, in which large lipid globules break down into several small, bile promotes lipid digestion. In the next step, lipids are broken down into glycerides and fatty acids by lipases, and then micelles from which they move into absorbing cells. (“Your digestive system & how it works,” n.d.). At the last stage of metabolism, the formed chylomicrons through the subclavian vein with exocytosis help move to the lymph nodes and finally into the blood cells.
References
Digestive System Processes. (n.d.). Lumen Learning.
Your digestive system & how it works. (n.d.). The National Institute of Diabetes and Digestive and Kidney Diseases.