B6 Gas exchange

• What is the definition of digestion?

  Hydrolysis of large insoluble molecules
• What are the three main types of macromolecules involved in digestion?

  • Carbohydrates
  • Lipids
  • Proteins
• What are the two types of enzymes involved in carbohydrate digestion?

  Amylases and membrane-bound disaccharidases
• Where is amylase produced?

  In the pancreas and salivary glands
• What is the initial site of carbohydrate digestion?

  The mouth
• What does amylase do to carbohydrates?

  Hydrolyzes starch into disaccharides
• What do endopeptidases do?

  Hydrolyze peptide bonds within protein chains
• What is the role of exopeptidases?

  Hydrolyze peptide bonds at the ends of chains
• Where does protein digestion begin?

  In the stomach
• What is the function of lipase?

  Hydrolyzes ester bonds in triglycerides
• Where are bile salts produced?

  In the liver
• What is the purpose of bile salts in lipid digestion?

  Emulsify lipids into smaller droplets
• How does emulsification benefit lipid digestion?

  Increases surface area for lipase action
• What are micelles?

  Spheres of fatty acids, monoglycerides, and bile salts
• Where does absorption of digested food occur?

  In the ileum
• What structures increase the surface area for absorption in the ileum?

  Villi and microvilli
• What happens to fatty acids and monoglycerides after absorption?

  They are reformed into triglycerides
• How are monosaccharides and amino acids absorbed?

  By co-transport, a type of active transport
• What is a chylomicron?

  A triglyceride combined with a protein
• How are chylomicrons released from epithelial cells?

  By exocytosis
• Where do chylomicrons enter after being released?

  Into the lacteal or lymph vessel
• What are the key processes involved in digestion and absorption?

  • Digestion: Hydrolysis of macromolecules
  • Absorption: Uptake of nutrients in the ileum
  • Enzymes: Amylases, lipases, and proteases
  • Structures: Villi and microvilli for increased surface area
• What enzyme is released by salivary glands for carbohydrate digestion?

  Amylase
• How is maltose converted to glucose?

  By membrane-bound disaccharidases
• What transports glucose into epithelial cells?

  Na+-transporter proteins
• What type of transport do sodium-dependent co-transporter proteins use?

  Active transport
• What happens to sodium ion concentration in epithelial cells during transport?

  It decreases
• Why is whole fruit considered better than fruit juice?

  Whole fruits contain fiber for gut health
• What component of fruit is beneficial for gut health?

  Fiber
• How does the absorption of sugars differ between whole fruit and fruit juice?

  Whole fruit absorption is gradual
• What effect does fast sugar absorption from juice have on insulin production?

  It causes a spike in insulin production
• What is the initial process of food breakdown called?

  Mechanical digestion
• What enzyme hydrolyzes starch into maltose in the mouth?

  Amylase
• Where is amylase produced besides the salivary glands?

  Pancreas
• What happens to maltose in the small intestine?

  It is broken down into glucose
• How are monosaccharides transported across epithelial cell membranes?

  By transporter proteins
• What type of adipose tissue is primarily found in babies?

  Brown adipose
• What is the function of brown adipose tissue?

  Heat generation
• How does the surface area to volume ratio change from babies to adults?

  It decreases
• What does a larger surface area to volume ratio mean for heat loss?

  Faster heat loss