12. Respiration

• Use of energy in the body:

  • muscle contraction
  • protein synthesis
  • cell division
  • active transport
  • growth
  • passage of nerve
  • maintenance of constant body temperature

  --> respiration involve the action of enzyme cells to speed up the reaction
• Aerobic respiration - the chemical reaction in cells that use oxygen to break down nutrient molecules to release energy

  --> glucose + oxygen -> carbon dioxide + water

  --> C6H12O6 + 6O2 -> 6CO2 + 6H2O

  • higher temperature = higher respiration rate
• Anaerobic respiration - the chemical reaction in cells that break down nutrient molecules to release energy without using oxygen

  --> muscles: glucose -> lactic acid

  --> yeast: glucose -> alcohol + CO2 ( C6H12O6 -> 2C2H5OH + 2CO2)

  • release much less energy per glucose molecule than aerobic respiration
• Lactic acid:

  • build up in muscles & blood during vigorous exercise
  • heart, liver & kidneys need extra oxygen to do this, causes you to continue breathing heavily after exercise
  • extra oxygen = oxygen debt
• Removal of oxygen debt:

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