Lecture 11

    Cards (11)

    • oxygen constant = 21%
      atmospheric pressure @ sea level = 100kPa
      so pressure oxygen = 21kPa
      therefore alevolar gas = 13.3kPa
    • atmoshpheric pressure at 5800m is half that at sea level = 9.3kPa
      on summit of everest = 5kPa
    • 60,000 feet, atmoshperic pressure 6.3kPa = same as SVP water
    • Response to altitude and acclimatisation:
      1. hyperventilation & respiratory alkalosis
      2. increased 2,3-DPG causes better unloading of oxygen
      3. polycythaemia, slow to develop
      4. bicarbonate excretion from CSF and kidneys
      5. diuresis, hyponatraemia
      6. acetazolamide used to treat acute mountain sickness
    • acute mountain sickness:
      breathless at > 2000m
      headache
      nausea
      loss apeptite
      difficulty sleeping/exercising
      amnesia/dizziness
    • severe mountain sickness
      cheyn stokes resp
      cerebral/pulmonary oedema
    • every 10m depth, pressure increases by 1atm = 100kPa
    • boyle's law = lung volume 6L compressed to 1L (residual volume) at this depth
    • deep diving:
      air supplied at environmental pressure
      helium oxygen used = 2% oxygen sufficient as gives pressure of alveolar oxygen 20kPa at 90m
      enables removal of Nitrogen
    • dive reflex:
      innate
      many mammals
      vasoconstriction so oxygen conserved to heart, lungs, brain
      reflex vagal bradycardia
      suppressed ventilation drive
    • hyperoxia = cellular oxygen toxicity
    See similar decks