Cardiovascular System

• What does an artery do?

  Arteries carry blood away from the heart and are made of thick muscular walls
• What do veins do?

  Carry blood toward the heart and have valves to stop blood flowing backwards
• What do capillaries do?

  Delivery of blood to tissues and organs and they are one cell thick
• How does gas change naturally occur in the lungs?

  The low concentration of CO2 in the lungs causes it to diffuse out of the blood into the lungs, and the low concentration of O2 in the blood causes it to diffuse into the blood
• Why are closed circulatory systems better than open?

  Closed are more efficient as blood is bound by vessels therefore having better blood flow to muscles and tissues, unlike open systems with unbound vessels meaning poor blood flow
• Why are double loop systems more efficient than single loop?

  Double systems are more efficient because there is always a direct supply of oxygenated blood unlike single loops which do not have a direct supply of blood leading to incosistent blood flow to tissues and muscles.