B9 - Respiration

• Cellular respiration

  • An exothermic reaction
  • Occurs continuousl in the mitochondria of living cells to supply the cells with energy
• What the energy released during respiration is used for


  • chemical reactions to build larger ,olecules
  • e.g. making proteins from amino acids
  • muscle contraction for movement
  • keeping earm
• Respiration in cells can take place aerobically, using oxygen, or anaerobically, without oxygen
• Aerobic respiration


  glucose + oxygen -> carbon dioxide + water
• Anaerobic respiration


  glucose -> lactic acid in muscles
• Fermentation


  • anaerobic respiration in plant and yeast cells
  • glucose -> ethanol + carbon dioxide
  • the products of fermentation are important in the manufacturing of bread and alcoholic drinks
• Response to exercise


  • Blood, heart rate, and breathing rate and volume increase
  • supplies more oxygenated blood to muscles
  • If insufficient, anaerobic respiration takes place
  • leads to the buildup of lactic acid in the muscles
  • During long periods of vigorous exercise, muscles become fatigued and stop contracting efficiently
• • After exercise, the lactic acid accumulated needs to be removed
• Oxygen debt


  the amount of oxygen needed to react with the lactic acid to remove it from cells
• Removal of lactic acid


  • lactic acid in muscles
  • transported to the liver in the blood
  • converted back to glucose
• Metabolism


  the sum of all reactions in a cell or the body
• The energy released by respiration in cells is used for the continual enzyme-controlled processes of metabolism that produce new molecules}
• Metabolic processes include the breakdown of:


  • carbohydrates
  • proteins
  • lipids
• Breakdown of carbohydrates


  • synthesis of carbohydrates from sugars
  • starch, glycogen and cellulose
  • breakdown of glucose in respiration to release energy
• Breakdown of proteins


  • synthesis of amio acids from glucose and nitrate ions
  • amino acids used to from proteins
  • excess proteins broken down to form urea for excretion
• Breakdown of lipids


  • synthesis of lipids from one molecule of glycerol and three molecules of fatty acid