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Transport in Animals (The Structure of the Heart (External Features…

- - - - Thin walls to push blood into ventricles
    - - Pumps blood to the lungs, low pressure to prevent damage to alveoli
    - - Thick walls contract to push blood around the body
      - Sufficient enough pressure needed to overcome resistance of the systemic circulation
- - - - The wave of excitation spreads over the walls of both atria, travelling along causing cardiac muscle cells to contract
    - - The wave of excitation is carried away from the AVN down specialised conducting tissues called Purkyne tissue. It runs down the intrerventricular septum and spreads over the ventricle walls from the base upwards
- - - - At low oxygen tension, haemoglobin doesn't readily associate with oxygen; the haem group is at the centre of the haemoglobin molecule making it difficult to combine with the first oxygen.
      - As oxygen tension rises, so goes the diffusion gradient causing the first oxygen to bind. This causes a conformational change in the haemoglobin shape so oxygen more readily associates with oxygen
      - At the highest oxygen tension, haemoglobin never becomes 100% saturate due to decreased probability of oxygen binding with the last haem group and that the partial pressure is never high enough for long enough to associate with the last oxygen