heart

• heart:

  • organ in the circulatory system
  • pumps blood around the body
• double circulatory system:

  • two circuits
  • deoxygenated blood flows into the right atrium and then into the right ventricle which pumps it to the lungs to undergo gas exchange
  • oxygenated blood flows into the left atrium and then into the left ventricle which pumps oxygenated blood around the body
• structure of the heart:

  • muscular walls to provide a strong heartbeat
  • muscular wall on the left is thicker because blood needs to be pumped all around the body rather than just to the lung - pressure
  • four chambers that separate oxygenated from deoxygenated blood
  • valves to prevent back flow of blood
  • coronary arteries cover the heart to provide its own oxygenated blood supply
• process:

  • blood flows into the right atrium through the vena cava and left atrium through the pulmonary
  • atria contract - forces blood into ventricles
  • ventricles contract
  • blood in the right ventricle into the pulmonary artery to be taken to the lungs
  • blood in left ventricle to the aorta to be taken around the body
• pacemaker cells:

  • control resting heart rate
  • found in right atrium
  • use electrical impulses
  • artificial pacemaker: can be used if individual has an irregular heartbeat