Circulatory System

• a way of moving the medium in the heart is when heart generates pressure gradient and other structures control direction of flow
• heart carries materials by plasma
• Why do we need a circulatory system?

  we have a low s.a.:volume ratio and are active organisms

  we need to transport oxygen from out lungs to respiring tissue to make ATP
• Closed system: blood in vessel

  more efficient as easier to maintain pressure
• Double circulation: oxygenated blood returns to heart

  to ensure enough pressure to pump blood to the rest of the body