Circulatory System

• The circulatory system has 2 distinct loops, one that carries deoxygenated blood from the heart to the lungs, and one where oxygenated blood goes from the lungs to the rest of the body.
• the heart has 4 chambers with thick muscular walls surrounding them
• Nearly all diagrams of the heart that you will see are inverted. The diagrams left is on our right, and the diagrams right is on our left.
• The top chambers are the left and right atrium (atria).
• the bottom chambers are the left and right ventricles (ventricles)
• Between the chambers are valves to ensure the blood is always flowing in the right direction.
• • Blood flows into the heart via the vena cava and the pulmonary vein
  • Vena cava into right atrium
  • Pulmonary vein into left atrium
  • Blood from the pulmonary vein has just come from the lungs so oxygenated
  • Blood from the vena cava is returning from the body and is deoxygenated
  • The blood is pushed into the ventricles
  • The ventricles contract and on the right push blood out of the pulmonary artery (to lungs) and on the left push blood out the aorta (to body)
  • The atria fill with new blood and the cycle repeats
• The cycle repeats on average 70x a minute, which is on average 1000 times a day.
• To keep the heart beat regulated there is a group of cells in the right atrium that act as a pacemaker. These cells produce small electrical impulses that cause the heart muscles to contract.
• Sometimes the pacemaker cells do not work. In these cases doctors can insert an artificial pacemaker, which is a small device that is implanted under the skin. It has a wire to carry an electrical current down to the heart telling it to contract regularly.
• A vein carries blood to the heart
• An artery carries blood away from the heart
• Coronary arteries surround the heart making sure the muscle gets all the oxygen and nutrients it needs.
• The three parts of the circulatory system are the blood, the blood vessels, and the heart.
• On each side of the heart, the atrium and ventricle are separated by a valve, which prevents the blood from flowing backwards.
• The left ventricle has thicker walls because it has to pump blood all the way around the body.
• Which blood vessel carries deoxygenated blood from the heart to the lungs?

  Pulmonary artery
• Body tissues ➔ vena cava ➔ right atrium ➔ right ventricle ➔ pulmonary artery ➔ lungs ➔ pulmonary vein ➔ left atrium ➔ left ventricle ➔ aorta ➔ body tissues
• 1. The walls of the atria contract, pushing blood into the relaxed ventricles.
  2. The walls of the ventricles contract, pushing blood out of the heart. At the same time, more blood will enter the now-relaxed atria.
  3. The cycle repeats.
• The coronary arteries supply the heart muscle with oxygen and nutrients.
• Label the image

  A) pulmonary artery

  B) aorta

  C) pulmonary vein

  D) left atrium

  E) valve

  F) left ventricle

  G) right ventricle

  H) valve

  I) right atrium

  J) vena cava

  
• Blood flowing from the heart to the lungs is under low pressure. If the pressure were too high, it might damage the lung tissue.
• the vena cava carries deoxygenated blood from the rest of the body back to the heart.