Topic 4.3 - Circulation

  • Substances are transported from where they enter the body to the cells or from the cells to where they are removed from the body, byt he circulatory system
    • This system consists of the heart, the blood vessels and the blood
  • The heart is an organ that pumps blood around the body
    • Much of the wall of the heart is made from muscular tissue
  • The heart has 4 main chambers
    • The right and left atria and the right and left ventricles
  • The natural resting heart rate is controlled by a group of cells located in the right atrium that act as a natural pacemaker.
    • Artificial pacemakers are electrical devices used to correct irregularities in the heart rate
  • In coronary heart dsease, layers of fatty material build up inside the coronary arteries, narrowing them.
    • This results in a lack of oxygen for the heart muscles
    • Stents are then used to keep the arteries open
  • In some people heart valves may become faulty, this could be because of two main faults:
    • The heart valve tissue may stiffen, preventing the valve from opening fully
    • The heart valve may have developed a leak
  • Faulty valves can be replaced in two ways:
    • Hiological valves- valves from humans or other mammals
    • Mechanical valves
  • Artificial Hearts are sometimes used to keep a patient alive while waiting for a heart transplant or to allow the hear to rest as an aid to recovery
  • Blood enters the atria of the heart, the atria contracts and force blood into the ventricles…


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