circulatory system

• Average adult blood volume

  4.7 to 5.6 liters
• Components of blood

  • Plasma (fluid part)
  • Red blood cells (transport oxygen)
  • White blood cells (defense)
  • Platelets (blood clotting)
• Heart


  • Four-chamber muscular organ
  • Located just behind and just to the left of the breastbone
  • Pumps blood through the cardiovascular system
• Arteries


  Carry oxygenated blood
• Veins


  Carry deoxygenated blood
• Blood vessels


  Network of arteries and veins that bring oxygenated blood from the heart, provide oxygen and nutrients to cells, and return deoxygenated blood to the heart
• Open circulatory system


  • Blood vessels carry all fluids to the cavity
  • Blood moves freely in both directions throughout the body
  • Blood bathes the body immediately, delivering oxygen and eliminating waste
• Slow blood movement in open circulatory systems

  • Lack of smooth muscles responsible for blood vessel contraction
• Examples of organisms with open circulatory systems

  • Crabs
  • Flies
  • Snails
• Closed circulatory system


  • Blood never leaves the blood vessels
  • Blood is continually moved from one blood vessel to another without entering the cavity
  • Blood is transported in one direction, supplying oxygen and nutrients to cells and removing waste materials
• Cardiovascular system


  • Provides nutrients and oxygen to all cells of the body
  • Consists of the heart and the blood vessels that run through the whole body
• Arteries


  Carry blood from the heart
• Veins


  Bring blood back to the heart
• Structure of blood vessels

  1. Trunk (primary artery/aorta)

  2. Branches through large arteries

  3. Leads to smaller and smaller vessels

  4. Smallest arteries wind up in capillary network
• Pulmonary circulatory system


  • Transports deoxygenated blood from the heart to the lungs and returns oxygenated blood from the lungs to the heart
• Pulmonary circulation


  1. Deoxygenated blood exits the heart from the right ventricle

  2. Transferred through the pulmonary artery to the lungs

  3. Carbon dioxide diffuses from the blood to the alveoli and is exhaled

  4. Oxygen diffuses through the alveoli and into the blood

  5. Oxygenated blood returns to the left atrium of the heart through the pulmonary vein
• Systemic circulation


  • Exits the heart, takes oxygenated blood to the cells of the body, and returns deoxygenated blood to the heart
• Systemic circulation


  1. Blood exits the left ventricle to the aorta

  2. Aorta connects to smaller arteries that supply all of the body's organs

  3. Arteries branch to the capillaries

  4. In the capillaries, oxygen diffuses from the blood to the cells, and waste and carbon dioxide diffuse from the cells into the blood

  5. Deoxygenated blood in the capillaries travels to the veins that converge into the upper and lower vena cava

  6. Deoxygenated blood enters the right atrium from the upper vena cava
• Major arteries in systemic circulation

  • Arteries to the brain
  • Arteries to the small intestine
  • Arteries to the liver
  • Arteries to the kidneys
  • Arteries to the muscles and skin