The heart-circulatory system

• Heart


  A unidirectional pump
• Valves


  • Present to prevent the backflow of blood
• Right side of the heart

  Pumps deoxygenated blood (low in oxygen and high in carbon dioxide) to the lungs
• Left side of the heart

  Pumps oxygenated blood (high in oxygen and low in carbon dioxide) to the organs of the body
• BODY_SYSTEMS_CIRCULATION_HEART_CROSS_SECTION

  1. Deoxygenated blood enters the right atrium from the vena cava

  2. Blood moves into right ventricle

  3. Blood is pumped into the pulmonary artery

  4. The pulmonary artery carries deoxygenated blood to the lungs

  5. The blood becomes oxygenated in the lungs

  6. Oxygenated blood leaves the lung via the pulmonary vein

  7. Blood enters the left atrium

  8. Blood moves into the left ventricle

  9. Blood is pumped into the aorta, which carries oxygenated blood around the body
• This unidirectional flow of blood through the heart shows that mammals have a double circulatory system
• Blood travels through the heart twice in one circulation of the body
• Ventricular walls


  • Thicker than atrial walls because the ventricles have to pump blood further
• Left ventricle wall


  • Thicker than the right because it pumps blood around the body while the right pumps blood to the lungs, located close to the heart
• Blood vessels and their functions

  • Vena cava - Carries deoxygenated blood from the body back to the heart
  • Pulmonary artery - Carries deoxygenated blood from the heart to the lungs
  • Pulmonary vein - Carries oxygenated blood from the lungs to the heart
  • Aorta - Carries oxygenated blood from the heart around the body
  • Hepatic artery - Carries oxygenated blood to the liver
  • Hepatic vein - Carries deoxygenated blood back to the heart. Carries digested food (glucose and amino acids) from the liver around the body
  • Hepatic portal vein - Carries digested food from the small intestine to the liver
  • Renal artery - Carries oxygenated blood (also rich in urea) to the kidneys for excretion
  • Renal vein - Carries deoxygenated blood (also low in urea as it has been purified in the kidney) back to the heart
• The oxygen and glucose carried in oxygenated blood is used for respiration in the body's cells
• Coronary arteries


  Provide the heart muscle with the glucose and oxygen it needs for respiration
• The coronary arteries are small blood vessels that branch off the aorta and can be seen on the external surface of the heart
• Pulmonary artery


  Blood vessel that carries deoxygenated blood from the right ventricle to the lungs
• Aorta


  Main artery that carries oxygenated blood from the left ventricle to the body
• Pulmonary vein


  Blood vessel that carries oxygenated blood from the lungs to the left atrium
• Vena cava


  Large vein that carries deoxygenated blood from the body to the right atrium