Lecture 03

• What is the primary function of the respiratory system?

  Gas exchange
• What are the normal partial pressures of O2 and CO2 in arterial and venous blood?

  • Arterial O2: ~100 mmHg
  • Arterial CO2: ~40 mmHg
  • Venous O2: ~40 mmHg
  • Venous CO2: ~45 mmHg

  
• How do PO2 and PCO2 contribute to gas exchange?

  They drive diffusion of gases across membranes
• What factors affect haemoglobin's affinity for O2 and CO2?

  • Temperature
  • pH levels
  • PCO2 levels
  • 2,3-BPG concentration

  
• What is the role of respiration in acid-base balance?

  It regulates CO2 levels to maintain pH
• What does Dalton’s Law state about total pressure?

  Total pressure is the sum of individual gas pressures
• How is the partial pressure of a gas determined?

  By its concentration and total pressure

  
• What happens to air as it travels through the respiratory tract?

  • It becomes humidified
  • Water vapor is added
  • Partial pressure of oxygen decreases
• What is dead space in the respiratory system?

  Air that does not reach alveoli for exchange
• What drives gas exchange in the lungs?

  Pressure differences between gases
• What is the thickness of the respiratory membrane?

  0.2 µm
• How does gas solubility relate to partial pressure according to Henry's Law?

  Concentration is proportional to partial pressure
• Which gas is more soluble in blood, O2 or CO2?

  CO2
• How is O2 transported in the blood?

  • 98.5% by haemoglobin
  • 1.5% dissolved in plasma
  • Haemoglobin binds O2 reversibly

  
• What percentage of O2 is carried by haemoglobin?

  98.5%
• What are the components of haemoglobin?

  4 subunits, each with a globin and haem group

  
• What is the significance of the oxyhaemoglobin and deoxyhaemoglobin states?

  They represent O2 binding and release

  
• What does the haemoglobin-oxygen dissociation curve illustrate?

  • Percentage saturation increases as PO2 increases
  • S-shaped curve indicates positive cooperativity
  • Systemic veins: 40 mmHg, 75% saturation
  • Systemic arteries: 100 mmHg, 98.5% saturation

  
• How does temperature affect O2 saturation in haemoglobin?

  Higher temperature decreases O2 affinity

  
• What is the Bohr effect?

  Lower pH increases O2 unloading from haemoglobin

  
• What factors decrease haemoglobin's affinity for O2?

  • Increased temperature
  • Decreased pH (Bohr effect)
  • Increased PCO2 (Carbamino effect)
  • Increased 2,3-BPG
  • Presence of CO

  
• What is the significance of pH homeostasis in the body?

  • Normal range: 7.35-7.45
  • Essential for enzyme function
  • Maintains metabolic processes
• How does the respiratory system regulate pH?

  By eliminating CO2 quickly
• What is the role of the kidneys in pH regulation?

  Elimination of H- and HCO3- slowly