The heart

• Circulatory system

  An example of an organ system whose role is to transport oxygen and nutrients to the body's tissues
• Circulatory system

  • Relies on 3 main things: blood, blood vessels, heart
• Blood


  Carries oxygen and nutrients
• Blood vessels


  Hold the blood
• Heart


  Pumps the blood to keep it moving through the vessels
• The circulatory system can be thought of as a double circulatory system
• Path of blood through the heart

  1. Flows into right atrium and left atrium

  2. Atria contract to push blood into ventricles

  3. Ventricles contract to push blood out into pulmonary artery and aorta

  4. Atria refill with new blood

  5. Cycle repeats around 70 times per minute
• Pacemaker cells


  Produce electrical impulses to make the heart contract regularly
• Artificial pacemaker


  Small device implanted under the skin above the heart to regulate the heartbeat
• Artery


  Any vessel that carries blood away from the heart
• Vein


  Any vessel that carries blood to the heart
• Arteries don't always carry oxygenated blood, and veins don't always carry deoxygenated blood
• Coronary arteries


  Small arteries that branch off the aorta to supply the heart muscle with oxygenated blood