7.3 Circulatory system of a mammal

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Created by
Sophie Grainger

Cards (11)

  • Whether or not there is a specialised transport medium and/or a pump mechanism depends on two factors. Firstly, the surface area to volume ratio of the organism. Secondly, how active the organism is.
  • The lower the surface area to volume ratio and the more active the organism, the greater need for a specialised transport medium and pump.
  • One feature of a transport system is suitable medium, such as water, to carry materials.
  • One feature of a transport system is a form of mass transport in which the transport medium is moved around in bulk over large distances.
  • One feature of a transport system is a closed system of tubular vessels that contains the transport medium and forms a branching network. This will allow the transport medium to be distributed to all parts of the organism.
  • One feature of a transport system is a mechanism to maintain the mass flow movement in one direction (e.g. valves).
  • One feature of a transport system is a means of controlling the flow of a transport medium to suit the changing needs of different parts of the organism.
  • One feature of a transport system is a mechanism for the mass flow of water or gases (e.g. intercostal muscles and diaphragm during breathing in mammals).
  • Mammals have a closed, double-circulatory system where blood is confined to vessels and passes through the heart twice for each complete circuit.
  • A double circulatory system is needed in mammals because when blood is passed through the lungs, the pressure is reduced. If the blood was then immediately pumped to the rest of the body, it's low pressure would make circulation very slow. As a result, blood is returned to the heart for a boost in pressure before being circulated around the body.
  • One feature of a transport system is a mechanism for moving the transport medium within vessels. This requires a difference in pressure. Animals use muscular contraction in the form of a specialised pumping organ (e.g. the heart) or the body muscles. Plants use natural, passive processes (e.g. evaporation).