the heart

• what are the 2 circulatory systems in mammals?

  • first circuit: the heart pumps deoxygenated blood to the lungs to take in oxygen. Oxygenated blood then returns to the heart.
  • second circuit: the heart pumps oxygenated blood around all the other organs of the body to deliver oxygen to the body cells. Deoxygenated blood returns to the heart.
• how do animals (fish) with single circulatory systems work?

  deoxygenated blood from the fish's body travels to the heart, which pumps it right round the body again in a single circuit (via the gills where it picks up oxygen).
• what are the mammalian heart's 4 chambers?

  • right atrium
  • left atrium
  • right ventricle
  • left ventricle
• what are the mammalian heart's 4 major blood vessels?

  • vena cava
  • pulmonary artery
  • pulmonary vein
  • aorta
• what is the role of the right atrium?

  it recieves deoxygenated blood from the body (through the vena cava).
• what is the role of the right ventricle?

  the deoxygenated blood moves through to the right ventricle, which pumps it to the lungs (via the pulmonary artery).
• what is the role of the left atrium?

  it recieves oxygenated blood from the lungs (through the pulmonary vein).
• what is the role of the left ventricle?

  the oxygenated blood then moves through to the left ventricle, which pumps it out round the whole body (via the aorta).
• how is the left ventricle different from the right ventricle?

  the left ventricle has a much thicker wall than the right.
• why is the left ventricle thicker wall than the right ventricle?

  it needs more muscle because it has to pump blood around the whole body at high pressure, whereas the right ventricle only has to pump it to the lungs.
• what is the purpose of valves in the heart?

  they prevent the backflow of blood in the heart.
• what is cardiac output?

  the total volume of blood pumped by a ventricle every minute.
• what is the equation for cardiac output?

  cardiac output = heart rate X stroke volume
• what is the heart rate and stroke volume?

  • heart rate: the number of beats per minute.
  • stroke volume: the volume of blood pumped by 1 ventricle each time it contracts.
• what are the 3 types of valves?

  • tricuspid valve
  • bicuspid valve
  • semi-lunar valve
• what does it mean if an animal has a double circulatory system?

  the heart pumps blood around the body in 2 circuits.
• how does blood enter the heart?

  via the atria
• what happens to the atria once it's filled with blood?

  it contracts, forcing blood down into the ventricles below.
• what happens when the ventricles contract?

  they force blood to exit the heart.
• what happens when a heart beats?

  Blood enters the heart via the atrium. The atrium fills with blood then contracts which forces it down below into the ventricles. Then the ventricles contract to force the blood to exit the heart.
• what controls the pumping of the heart?

  a group of cells in the right atrium
• why might someone be fitted with an artificial pacemaker?

  a group of cells in the right atrium act as a pacemaker to control the hearts beating. Irregular heart rates can be corrected using electrical devices, known as artificial pacemakers.
• which ventricle has thicker walls?

  left ventricle
• what type of organ is the heart?

  Muscular organ
• where does the heart recieve deoxygenated blood from?

  the vena cava
• where does the heart recieve oxygenated blood from?

  from the lungs through the pulmonary vein.
• how does the heart pump oxygenated blood to the body?

  through the aorta
• how does the heart pump deoxygenated blood to the lungs?

  through the pulmonary artery
• what is the role of coronary arteries?

  supply the heart muscle with oxygenated blood.
• what is cardiac output?

  the volume of blood pumped each minute by each ventricle.
• what is stroke volume?

  volume of blood pumped by each ventricle with each heartbeat.
• what is the role of the pulmonary artery?

  the heart pumps deoxygenated blood to the lungs hrough this artery.
• what is the role of the pulmonary vein?

  the heart recieves oxygenated blood from the lungs through this vein.
• what is the role of the vena cava?

  the heart recieves deoxygenated blood from the body through this vein.
• what is the role of the aorta?

  the heart pumps out oxygenated blood to the body through this artery.
• which blood vessel supplies the heart with oxygenated blood?

  coronary arteries.
• where does deoxygenated blood from the body enter the heart from?

  the right atrium
• what happens to the deoxygenated blood once it enters the heart through the right atrium?

  it's pumped out of the heart and towards the lungs by the right ventricle.
• what happens to deoxygenated blood once it reaches the lungs?

  the deoxygenated blood exchanges carbon dioxide for oxygen which is how it becomes oxygenated.
• what happens to the blood once it has become oxygenated?

  it returns to the left atrium of the heart.