Single and double circulatory systems

• What is mass transport?

  When molecules are carries in a medium.
• single circulatory system

  blood only passes through heart once. For example fish
• What is the major problem of single systems?

  Blood pressure is very low- so demand for oxygen is not always reached as speed of oxygen is low.
• Double circulatory system

  Blood passes through heart twice- humans.

  Ensures that blood moves to body tissues rapidly and at high pressure.
• Closed system

  • Blood is always contained in blood vessels.
  • blood moves fast
  • blood can be shunted
• open system:

  • insects- no blood
  • contain haemolymph which carries sugars not oxygen
  • haemolymph is pumped out insects heart into haemocoel( insects body cavity) where it transfers molecules and returns to heart
  • is very slow and cant be shunted