(12) respiration

• uses of energy: muscle contraction, protein synthesis, cell division, active transport, growth, passage of nerve impulses, maintenance of constant body temperature
• aerobic respiration: chemical reactions in cells that use oxygen to break down nutrient molecules to release energy 

  • glucose + oxygen —> carbon dioxide + water
  • C6H126O2 —> 6CO2 + 6H2O
• anaerobic respiration: chemical reaction in cells that break down nutrient molecules to release energy without using oxygen

  • anaerobic respiration releases much less energy per glucose molecule then aerobic respiration
• anaerobic respiration in yeast:

  • glucose —> alcohol + carbon dioxide
  • C6H12O6 —> 2C2H5OH + 2C02
• anaerobic respiration in muscles during vigorous exercise:

  • glucose —> lactic acid
  • lactic acid builds up in muscles and blood during vigorous exercise causing an oxygen debt
• oxygen dept removed by:

  • fast heart rate to transport lactic acid in blood from muscles to liver
  • deeper and faster breathing to supply oxygen for aerobic respiration of lactic acid
  • aerobic respiration of lactic acid in liver