Enzymes hydrolyze carbohydrates, proteins and fats into absorbable units.
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Digestion is the chemical breakdown of large food molecules into small units that can be absorbed through the intestinal wall. Salivary and pancreatic amylase hydrolyse starch into maltose and other small sugars. Pepsin in the acidic stomach begins protein digestion, and trypsin, chymotrypsin and peptidases in the small intestine release amino acids and short peptides. Lipases, aided by bile salts that emulsify fat into small droplets, convert triglycerides into fatty acids and monoglycerides. Most absorption occurs in the small intestine, where the villi and microvilli provide a huge surface area.
Key ideas: Digestion is hydrolysis. Salivary amylase breaks starch, pepsin (pH about 2, stomach HCl) cuts proteins, pancreatic lipase with bile salt emulsification breaks fats, and trypsin and chymotrypsin finish proteins in the small intestine at pH about 8. Bicarbonate from the pancreas neutralizes the acid chyme.
Common mistakes and connections: Students think the stomach absorbs most nutrients, but absorption is mainly in the small intestine through villi. Bile is not an enzyme; it emulsifies and increases the surface area. Enzymes work at different pH values, so each has its own optimum. Links to enzymes, polysaccharides and antacids.
The pH along the digestive tract. Acidic stomach conditions suit pepsin, while the near-neutral to alkaline small intestine suits pancreatic enzymes. The interactive lesson shows this as a live animation or chart.
Bile salts break a large fat globule into tiny droplets so that pancreatic lipase can act on a far greater surface area.
Enzymes hydrolyze carbohydrates, proteins and fats into absorbable units.
Digestion Chemistry is a intermediate topic in Biochemistry, Environment & Industry. It builds on the vocabulary of beginner topics in this area.
Study these earlier topics in Biochemistry, Environment & Industry first: Calvin Cycle, Cellular Respiration, Fermentation.
The next topics in Biochemistry, Environment & Industry are Drug Action and Antibiotics.
Yes. The interactive lesson includes a self-check question on Digestion Chemistry, and the Biochemistry, Environment & Industry quiz draws on every topic in this area.
Digestion Chemistry is topic 41 of 127 in Biochemistry, Environment & Industry.
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