topic 3

• Digestion


  Large insoluble molecules are hydrolyzed into smaller soluble molecules which can then be absorbed across cell membranes and into the bloodstream
• Molecules digested


  • Carbohydrates
  • Lipids
  • Proteins
• Amylases


  Enzymes that hydrolyze carbohydrates
• Carbohydrate digestion


  1. Amylases in saliva hydrolyze polysaccharides into disaccharides

  2. Disaccharidases in small intestine hydrolyze disaccharides into monosaccharides
• Protein digestion


  1. Endopeptidases hydrolyze peptide bonds within the protein chain

  2. Exopeptidases hydrolyze peptide bonds at the ends of the chain

  3. Dipeptidases hydrolyze dipeptides into amino acids
• Lipid digestion


  1. Lipase hydrolyzes triglycerides into fatty acids and glycerol

  2. Bile salts emulsify lipids to increase surface area for lipase
• Micelles


  Spheres made of fatty acids, monoglycerides, and bile salts that deliver lipids to epithelial cells
• Villi and microvilli


  • Increase surface area for absorption in the small intestine
• Monosaccharide and amino acid absorption

  Occurs by co-transport (active transport)
• Lipid absorption


  Fatty acids and monoglycerides diffuse into epithelial cells, are re-esterified into triglycerides, packaged into chylomicrons, and released into lacteals
• Red blood cell


  Contains hemoglobin to transport oxygen in the blood
• Hemoglobin


  A quaternary structure protein with four polypeptide chains, each containing a heme group with iron that binds oxygen
• There are different types of hemoglobin found in different organisms and tissues
• Affinity


  The ability of hemoglobin to attract and bind oxygen
• Saturation


  The maximum amount of oxygen that hemoglobin can bind
• Loading/Association


  When oxygen is binding to hemoglobin
• Unloading/Dissociation


  When oxygen is detaching or unbinding from hemoglobin
• Oxyhemoglobin dissociation curve


  • Sigmoid (S-shaped) curve
  • Demonstrates how hemoglobin's affinity for oxygen changes at different partial pressures of oxygen
• High partial pressure of oxygen

  Hemoglobin is almost 100% saturated with oxygen
• Low partial pressure of oxygen

  Hemoglobin is only about 50% saturated with oxygen
• Cooperative binding


  The first oxygens bind with difficulty, but then make it much easier for subsequent oxygens to bind
• Bohr effect


  The decrease in hemoglobin's affinity for oxygen when there is a high concentration of carbon dioxide, which makes the blood more acidic
• High carbon dioxide concentration

  Oxyhemoglobin dissociation curve shifts to the right, indicating decreased affinity for oxygen
• Low carbon dioxide concentration

  Oxyhemoglobin dissociation curve shifts to the left, indicating increased affinity for oxygen
• Hemoglobin types in different animals

  • Fetal hemoglobin (higher affinity)
  • Llama hemoglobin (higher affinity at low oxygen pressures)
  • Dove hemoglobin (lower affinity for faster unloading)
  • Earthworm hemoglobin (higher affinity at low oxygen pressures)
• Different hemoglobin types allow organisms to adapt to their environments by adjusting oxygen binding and release
• Tissue fluid


  Liquid which surrounds the cells in the body
• Tissue fluid


  • Contains water, glucose, amino acids, fatty acids, dissolved ions and minerals, oxygen
• Formation of tissue fluid

  1. Capillaries are one cell thick with tiny gaps

  2. Arterioles attached to arteries have high pressure

  3. High pressure causes ultrafiltration

  4. Water and small molecules forced out of capillaries

  5. Large molecules and some water remain in capillaries
• Molecules forced out of capillaries

  • Water
  • Dissolved minerals and salts
  • Glucose
  • Small proteins
  • Individual amino acids
  • Fatty acids
  • Oxygen
• Molecules that remain in capillaries


  • Red blood cells
  • Platelets
  • Large proteins
• Reabsorption of tissue fluid

  1. At venule end of capillary bed

  2. Negative water potential in capillary

  3. Water reabsorbed by osmosis

  4. Dissolved waste molecules like CO2 and urea also reabsorbed
• Not all tissue fluid is reabsorbed by osmosis
• Lymphatic system


  Absorbs any remaining tissue fluid not reabsorbed into capillaries
• Lymphatic system brings liquid back into the blood near the heart
• Spirometer


  Device used to measure lung capacity
• Using a spirometer


  1. Take a deep breath

  2. Blow out as hard as possible through mouth

  3. Wear nose clip to prevent air entering/escaping through nose
• Spirometer graph


  • Shows breathing in and out normally (tidal volume)
  • Shows maximum inhale and exhale (vital capacity)
  • Shows residual volume (air that permanently stays in lungs)
  • Total lung capacity is vital capacity plus residual volume
• Pulmonary ventilation


  Total volume of air that moves in and out of the lungs in one minute
• Calculating pulmonary ventilation


  Tidal volume x Ventilation rate (breaths per minute)