Molecular breakdown/absorption of Polysaccharides Lipids Proteins Stage 1 Digestion Molecular breakdown/absorption of Polysaccharides Lipids Proteins

Starches MOUTH: salivary amylase hydrolyzes some glycosidic bonds of amylose Formation of dextrins: 3-8 glucose units STOMACH (pH 2) denatures salivary amylase –stops further carb digestion DUODENUM/PANCREAS Secretion of pancreatic amylase completes digestion to maltose

STARCHES SMALL INTESTINE Mucosa cells lining SI secrete lactase Lactose → galactose + glucose sucrase Sucrose → fructose + glucose maltase Maltose → glucose + glucose Absorption of monosaccharides into blood stream

Lipids Mouth- Stomach: no effect on lipids DUODENUM: bile salts from the gall bladder emulsify fat into tiny droplets called micelles

Lipids DUODENUM Pancreatic lipase hydrolyzes lipids triglycerides → monoglycerides + 2 FA SMALL INESTINE Absorption into blood stream Transport in the blood via lipoprotein vesicles

Proteins MOUTH: no effect on proteins STOMACH contains HCl, pH 2 a. General acid denaturing of proteins b. Secretion of enzyme pepsin hydrolyzes peptide bonds, formation of small peptides pepsin Proteins → peptides

Proteins DUODENUM/PANCREAS Pancreatic enzymes Trypsin/ Chymotrypsin hydrolyze peptides into AA SMALL INTESTINE AA are absorbed into blood stream