Circulatory System

• Describe the circulatory system of a mammal.

  Closed, double circulatory system.
• What does closed mean in the context of circulatory systems?

  Closed means the blood remains within the blood vessels.
• What does double circulatory system refer to?

  The double circulatory system refers to the fact that the blood passes through the heart twice in each circuit. There is one circuit which delivers blood to the lungs and another circuit which delivers blood to the rest of the body.
• Why do mammals need a double circulatory system?

  To manage the pressure of blood flow. The blood flows through the lungs at a lower pressure. This prevents damage to the capillaries in the alveoli and also reduces the speed at which the blood flows, enabling more time for gas exchange.
• Why does blood leave the heart at high pressure?

  The oxygenated blood from the lungs then goes back through the heart to be pumped out at a higher pressure to the rest of the body. This is important to ensure that the blood reaches all the respiring cells in the body.