Enzymes for digestion of macromolecules Carbohydrates: carbohydrases - Polysaccharides – disaccharides - monosaccharides Proteins: proteases - Proteins – polypeptides – peptides – amino acids Lipids: lipases - Lipids – glycerol and fatty acids Nucleic Acid: nucleases - Nucleic Acids – nucleotides – sugars, phosphates, nitrogenous bases

1. MOUTH Carbohydrates: Salivary Amylase

2. STOMACH Proteins: Pepsin

3. SMALL INTESTINE Carbohydrates: pancreatic amylase sucrase maltase lactase Proteins: Trypsin Chymotrypsin Peptidases

3. SMALL INTESTINE Lipids: Bile Lipases Nucleic Acids:Nucleases Nucleosidases

Factors affecting enzyme action include: 1. Temperature 2. pH

Factors affecting enzyme action include: 1. Temperature - Increase temperature - Increase enzyme activity - Chemical bonds within enzymes weaken - Enzyme denatures (change in molecular shape and structure) ** Each enzyme can work within a narrow range of temperatures

Factors affecting enzyme action include: 2. pH - Change in pH - Enzyme denatures (change in molecular shape and structure) ** Each enzyme can work within a narrow range of pH

1. CARBOHYDRATES - Carbohydrates are digested - Monosaccharides are absorbed by the lining of the small intestine - Monosaccharides are delivered to the liver and converted to glucose - Glucose is delivered to all parts of the body - Excess glucose is stored in the liver as glycogen (minimal amounts stored in muscles)

2. PROTEINS - Proteins are digested - Amino acids are absorbed by the lining of the small intestine - Monosaccharides are delivered to the liver and processed - Converted to sugars - Used in energy-releasing chemical reactions - Converted into urea which is later filtered and excreted in urine - Amino acids are carried by circulatory system to cells of body

2. LIPIDS - Lipids are digested - Glycerol and fatty acids are absorbed by the lining of the small intestine then reassembled into triglycerides - Triglycerides are coated with proteins to become water-soluble - Protein-coated triglycerides are transferred to the bloodstream - Protein coating is removed and triglycerides are broken down by lipase enzymes back to glycerol and fatty acids - Used for energy

Main functions: - Hold remaining material not absorbed in small intestine - Reabsorb water (~90%) back into the blood and extra-cellular fluid - Anaerobic bacteria break down undigested matter further - Some produce important vitamins (Ex. Folic acid, B vitamins, vitamin K) which are absorbed back into blood - Also produce fecal odour - Feces formation -Brown colour due to break down of bilirubin (from hemoglobin)