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A model to help describe how the body delivers oxygen to the tissues

This model was inspired by the October 2013 Great Gathering of the Gresley A4 Pacifics at the UK National Railway Museum in York, UK, and is dedicated to the Mallard.

The Trains

The oxygen train

The Tracks

The oxygen train

In the oxygen train,

  • Each train carriage represents a haemoglobin molecule containing four iron "seats", able to transport 4 oxygen molecules (red dots).

  • There is very little seat-free travel unless extra oxygen is provided through a face mask.

  • The heart is the engine driving trains (red blood cells) round the tracks (circulation), with uphill gradients representing sites of higher vascular resistance.

  • Oxygen is delivered to the tissues for metabolic ‘work’ at a factory that works in two modes- green (aerobic)  produces less CO2/H+ (smoke), than polluted (anaerobic). The mode used is determined by the type of work, rate of oxygen arrival, and tissue efficiency mechanisms.   

  • Work rate increases (e.g. exercise, sepsis) require increased oxygen delivery and produce more smoke.

  • Ventilation (breathing) is set to keep the smoke (CO2/H+) at a steady level in the blood stream.  


For further details and explanation of these images, please click one of the titles below:

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