circulatory systems (3)

• open circulatory system?

  as heart contracts, blood is pushed into bodies cavities. as heart relaxes, blood is drawn back to heart through gills picking up oxygen on the way under low pressure. blood will surround organs.
• single/double closed circulatory system?

  • single= blood flows through heart in one complete circuit, at low pressure when reaching capillaries.
  • double= blood flows through heart in two complete circuits, referred to as 'extra boost'.
• advantages of double circulatory system?

  • ox and deox blood cannot mix, tissues receive max oxygen.
  • blood travels slowly through lungs/tissues to enable efficient gas exchange
  • blood travels twice so ox blood is sent at high pressure
  • waste substances are removed more efficiently
• what has evolution of double circulatory system allowed mammals to do?

  • maintain constant body temp
  • have higher metabolic rate
  • be more active
  • develop higher brain functions
• what makes a circulatory system 'closed', and what are its advantages?

  blood vessels, blood has a direct flow and can flow at a higher pressure therefore flows quicker to tissues