The Heart and Circulation

• The problem with a single circulatory system is that the blood loses a lot of pressure, meaning that it travels slowly and cannot deliver a great deal of oxygen.
• Humans have a double circulatory system:

  1. Deoxygenated blood is pumped from the heart to the lungs
  2. Oxygenated blood returns to the heart
  3. Oxygenated blood is pumped from the heart to the organs
  4. Deoxygenated blood is pumped from the organs back to the heart
  5. The process repeats

  A) Lungs

  B) Heart

  C) Organs

  D) Double

  
• Fish have a single circulatory system:

  1. Deoxygenated blood moves from the heart to the gills
  2. Then Oxygenated blood moves from the gills to the organs
  3. Deoxygenated blood moves from the organs to the heart
  4. The process repeats

  A) Organs

  B) Heart

  C) Gills

  D) Single

  
• The benefit of a double circulatory system is that because the blood passes through the heart twice, it can travel rapidly through the body cells, delivering the oxygen that the cells need
• The heart is an organ consisting mainly of muscle tissue. the heart pumps blood around the body.
• The heart has four chambers:

  • Left Atrium
  • Right Atrium
  • Left Ventricle
  • Right ventricle

  The atria are separated from the ventricles by valves

  A) Right Atrium

  B) Left Atrium

  C) Valves

  D) Valves

  E) Left Ventricle

  F) Right Ventricle

  
• The process of the heart:

  1. The vena cava brings in deoxygenated blood from the body
  2. The blood passes from the heart to the lungs in the pulmonary artery
  3. Oxygenated blood passes from the lungs to the heart in the pulmonary vein
  4. Oxygenated blood is pumped from the heart to the body in the aorta

  A) Vena cava

  B) pulmonary artery

  C) aorta

  D) pulmonary vein

  
• The movement of blood in the heart:

  1. Blood enters the left & right atria
  2. The atria contract and blood is forced into the ventricles
  3. The ventricles contract and force blood out of the heart
• The valves stop the blood from flowing backwards into the atria when the ventricles contract
• The left side of the heart has a thicker muscular wall than the right side because the left ventricle pumps blood around the whole body, so is required to provide a greater force
• The coronary arteries branch out of the aorta and spread out in the heart muscle. They provide oxygen to the muscle cells of the heart which is used in respiration to provide the energy for contraction.

  A) Coronary artery

  
• The natural, resting heart rate is controlled by the pacemaker. If the pacemaker stops working correctly, doctors implant an artificial pacemaker which is a small electrical device that corrects irregularities in the heart rate.