B2.3 the circulatory system

• Circulatory system


  An example of an organ system, its role is to transport oxygen and nutrients to the body's tissues
• Circulatory system

  • Relies on 3 main things: blood, blood vessels, heart
• Blood flow through the circulatory system

  1. Blood flows from heart to lungs, gains oxygen, flows back to heart

  2. Oxygenated blood flows from heart to body, gives up oxygen, flows back to heart
• Heart


  Consists of 4 chambers with thick muscular walls, veins and arteries
• When looking at a diagram of the heart, the left side is on the right and the right side is on the left
• Atria


  Top chambers of the heart
• Ventricles


  Bottom chambers of the heart
• Valves


  Prevent blood from flowing backwards, ensure blood flows in the right direction
• Blood flow through the heart


  1. Flows into right atrium and left atrium

  2. Atria contract, push blood into ventricles

  3. Ventricles contract, push blood into pulmonary artery and aorta

  4. Atria refill with new blood, cycle repeats
• Pacemaker cells


  Group of cells in the right atrium that produce electrical impulses to make the heart contract
• Artificial pacemaker


  Small device implanted under the skin above the heart, with a wire that carries electrical current to the heart
• Artery


  Any vessel that carries blood away from the heart
• Vein


  Any vessel that carries blood to the heart
• Arteries don't always carry oxygenated blood, and veins don't always carry deoxygenated blood
• Coronary arteries


  Small arteries that branch off the aorta and encircle the heart to supply it with oxygenated blood