gas exchange

• Explain how ventilation rate is changed during vigorous physical exercise:

  1. exercise increases the rate of cellular respiration
  2. increases production of CO2
  3. increased CO2 causes increased acidity in blood
  4. chemoreceptors in aorta/carotid artery/medulla oblongata detect change in pH
  5. impulse/signal/message to breathing centre AND intercostal muscles AND diaphragm for more frequent contraction
  6. increase ventilation rate for more gas exchange OR vital capacity
  7. long term effects of increased lung surface area
  8. training decreases ventilation rate over time
•  Explain the Bohr shift:

  1. respiring tissues produce CO2;
  2. CO2 leads to an increase in H+/decrease in blood pH
  3. increased acidity/decreased pH shifts the oxygen dissociation curve to the right;
  4. affinity of the hemoglobin for oxygen is reduced;
  5. greater release of oxygen from hemoglobin (at the same partial pressure of oxygen) in tissues;

  
• Mode of transportation of CO2:

  1. dissolved/carried in plasma
  2. forms carbonic acid; as hydrogencarbonate
  3. binds to haemoglobin
• O2 dissociates more at lower pO2 from Hb (than at higher pO2), providing more O2 to respiring tissues
• Discuss high altitude training for athletes:

  Pros

  1. improved performance/endurance at low O2 levels
  2. due to higher concentration of RBC
  3. more O2 transported
  4. improved gas exchange
  5. increase in myoglobin/mitochondria

  Cons

  1. altitude sickness/low immunity
  2. increased muscle tissue breakdown
  3. effects are not immediate
  4. unfair for competitors who cannot train at high altitudes