Digestion and absorption

• What is the process of digestion?

  Breakdown of large molecules into smaller ones
• Why can't large molecules like starch be absorbed into the bloodstream?

  They are too big to cross cell membranes
• What type of reactions are involved in digestion?

  Hydrolysis reactions
• What do hydrolysis reactions do?

  Break bonds through the addition of water
• What are carbohydrates broken down into during digestion?

  Disaccharides and then monosaccharides
• What are fats broken down into?

  Glycerol and fatty acids
• What are proteins broken down into?

  Amino acids
• What enzyme breaks down starch into maltose?

  Amylase
• What are the two polysaccharides that make up starch?

  Amylose and amylopectin
• What type of bonds does amylase break during hydrolysis?

  Glycosidic bonds between glucose monomers
• Where is amylase produced?

  Salivary glands and pancreas
• What is the role of the pancreas in digestion?

  Production and secretion of enzymes
• What do membrane-bound disaccharidases do?

  Break down disaccharides into monosaccharides
• Where are membrane-bound disaccharidases found?

  On the surface of epithelial cells in the ileum
• What is maltase's specific function?

  Break down maltose into two glucose monomers
• How are disaccharides transported into the bloodstream?

  By specific transporter proteins across epithelial cells
• What are lipids broken down into?

  Monoglycerides and fatty acids
• What catalyzes the breakdown of lipids?

  Lipase enzymes
• Where are lipases produced?

  In the pancreas
• What is the role of bile salts in lipid digestion?

  Emulsify lipids to increase surface area
• What happens during emulsification of lipids?

  They form small droplets to increase surface area
• What do monoglycerides and fatty acids combine with to form micelles?

  Bile salts
• What are endopeptidases responsible for?

  Hydrolyzing peptide bonds within a protein
• What is trypsin?

  An endopeptidase synthesized in the pancreas
• Where is pepsin synthesized and released?

  In the stomach
• What do exopeptidases do?

  Hydrolyze peptide bonds at the ends of proteins
• What are dipeptidases?

  A specific kind of exopeptidase that hydrolyzes dipeptides
• Where are dipeptidases often found?

  In the cell membrane of epithelial cells
• How are the products of digestion absorbed into the bloodstream?

  Transported across the ileum epithelium
• What mechanisms are used to absorb monosaccharides and amino acids?

  Cotransport and facilitated diffusion
• How are glucose and galactose absorbed?

  Using the sodium cotransport mechanism
• How is fructose absorbed?

  Using a different transporter protein via facilitated diffusion
• How are amino acids absorbed?

  Using sodium-dependent transporter proteins
• How are monoglycerides and fatty acids absorbed?

  Using micelles
• What happens when micelles break up?

  They release products across the epithelial membrane
• What are the main organs involved in digestion?

  • Salivary glands
  • Tongue
  • Oesophagus
  • Liver
  • Stomach
  • Ileum
  • Anus
  • Rectum
  • Pancreas
  • Colon
  • Duodenum
  • Bile duct
  • Gallbladder
• What is the role of the small intestine in digestion?

  • Absorbs products of digestion
  • Transported across ileum epithelium into bloodstream
• What is the structure of the human ileum that aids absorption?

  • Villi present
  • Increase surface area for absorption