chap 5.2 nutrients in human

• Digestion is process whereby large food molecules are broken down into smaller, soluble molecules taht can be absorbed into the body cells.
• digestion has two categories:

  • physical
  • chemical
• physical digestion is like chewing food, peristalsis and when fat is broken down into smaller molecules. physical digestion increases the surface area to volume ratio of ingested food so that digestive enzymes can act on food more efficiently
• chemical digestion is breaking down of large food molecules in food such as proteins, starch and fats into smaller soluble molecules so hat they can be absorbed

  
• proteins are digested by protease to get polypeptides
• saliva contains salivary amylase whihc digest starch to maltose.
• starch broken down by pancreatic amylase gives maltose and maltose is brokcen down by maltase to get glucose
• protein digested in stomach or small intestine broken down by protease gives polypeptides and polypeptides broken down in the small intestine by protease give amino acids
• emulsification is the breaking up of fats into tiny fat droplets
• fats broken down by lipase gives fatty acids and glycerol
• big fat droplets is emulsified by bile salts turns into tiny fat droplets
• Mouth

  1. Secretes saliva from salivary glands

  2. Enzyme salivary amylase breaks down starch to maltose
• Stomach

  1. Secretes gastric juices from gastric glands

  2. Enzyme protease breaks down proteins to polypeptides
• Small intestine

  1. Secretes bile from liver which emulsifies fats

  2. Secretes pancreatic juice from pancreas which contains enzyme protease, pancreatic amylase and lipase which breaks down proteins to polypeptides, starch to maltose and fats to fatty acids and glycerol

  3. Secretes intestinal enzymes from epithelial cells with enzyme lipase, protease and maltase which breaks down fats to fatty acids and glycerol, polypeptides to amino acids and maltose to glucose