Respiration

• What is aerobic respiration ?

  breakdown of glucose in the presence of oxygen, which releases a large amount of energy for the body. This process occurs in the mitochondria.
• Word equation of AR:

  Glucose + Oxygen -> carbon dioxide + water
• Chemical equation of AR:

  C6H12O6 + 6O2 -> 6CO2 + 6H2O
• What is anaerobic respiration ?

  breakdown of glucose in the absence of oxygen, which releases a small amount of energy
• Word eqn of AR2:

  Glucose -> Lactic acid
• Muscles incur an oxygen debt after exercise so lactic acid can be oxidised.
• What happens during exercise?

  • (Muscle cells need more energy to contract, so there is increased aerobic respiration to increase energy released.)
  • When vigorous activity continue, muscle cell carry out anaerobic respiration to meet increased energy demand and release extra energy for body.
  • Aerobic and Anaerobic respiration incur a oxygen debt.
• After exercise

  • liver obtains oxygen supply to oxidise lactic acid to go back to aerobic respiration
  • body goes back to normal heart rate and breathing when all lactic acid is removed
• Nose functions:

  • Dust and foreign particles are trapped in nostril hair
  • Air is warmed and moistened as it enters nasal passage
• Trachea functions:

  • Gland cells; secrete mucus to trap dust particles
  • Ciliated cells; sweep dust-trapped mucus
• How are lungs adapted for gas exchange?

  1. Numerous alveoli -> larger surface area
  2. Wall of alveolus is one cell thick -> short diffusion distance for gases, increased rate of diffusion
  3. A thin film of moisture covers inner wall -> allows oxygen to dissolve in gaseous form
  4. Numerous blood capillaries -> maintains concentration gradient of gases between alveolar air and blood
• Oxygen diffuse into red blood cells blood plasma while carbon dioxide diffuses out into alveolus.