The circulatory system/heart

• Circulatory System


  The system that circulates blood around the body
• Heart


  The pumping organ that keeps the blood flowing around the body
• Heart


  • The walls of the heart are made of muscle
  • The heart contracts to pump blood around the body
• How the heart pumps blood

  1. Blood flows into the atria

  2. The ventricles contract, forcing the blood into the pulmonary artery and aorta

  3. The atria fill again and the whole cycle starts
• The heart also needs its own supply of oxygenated blood
• Pacemaker


  A group of cells in the right atrium that set the pace for the heart's contractions
• How the pacemaker works

  1. The pacemaker cells produce an electrical impulse

  2. The impulse spreads to the surrounding muscle cells, causing them to contract
• Artificial pacemaker


  A device implanted under the skin with a wire going to the heart to produce an electrical current to keep the heart beating regularly
• When doctors use a stethoscope to listen to your heart, it's the valves closing that they hear