Heart & Circulation

• Circulatory system


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

  • 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
• Double circulatory system


  Two distinct loops - one carries deoxygenated blood from the heart to the lungs where it gains oxygen and then flows back to the heart, the other carries oxygenated blood to the rest of the body where it gives up its oxygen to the tissues becoming deoxygenated and then flows back to the heart
• Heart


  • Consists of four chambers with thick muscular walls, and veins and arteries coming in and out
• When looking at an image of the heart, the left side is on the right and the right side is on the left
• Atria


  Top chambers of the heart
• Ventricles


  Bottom chambers of the heart
• Valves


  Prevent the blood from flowing backwards, ensuring it always flows in the right direction
• Path of blood through the heart

  1. Flows into the heart via the vena cava and pulmonary vein

  2. Flows into the right and left atria

  3. Atria contract and push blood into the ventricles

  4. Ventricles contract and push blood out into the pulmonary artery and aorta

  5. Atria refill with new blood and the cycle repeats
• Pacemaker cells


  Group of cells in the right atrium that produce small electrical impulses to keep the heart beating at a steady rate
• Artificial pacemaker


  Small device implanted under the skin above the heart that can carry electrical current to the heart to make it contract regularly
• Artery


  Any vessel that carries blood away from the heart
• Vein


  Any vessel that carries blood to the heart
• Arteries do not always carry oxygenated blood, and veins do not always carry deoxygenated blood
• Coronary arteries


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