Circulatory system and the heart

• What makes up the circulatory system

  • Relies on 3 main things: blood, blood vessels, heart
• How does 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
• What does the heart consist of?

  Consists of 4 chambers with thick muscular walls, veins and arteries
• What are the atria?

  Top chambers of the heart
• What are the ventricles?

  Bottom chambers of the heart
• What do valvesdo?

  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
• What are pacemaker cells

  Group of cells in the right atrium that produce electrical impulses to make the heart contract
• How does an artificial pacemaker work?

  Small device implanted under the skin above the heart, with a wire that carries electrical current to the heart
• What is an artery

  Any vessel that carries blood away from the heart
• What is a vein

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

  Small arteries that branch off the aorta and encircle the heart to supply it with oxygenated blood
• The heart acts as the pump for the circulatory system
• What are the different blood vesselsand what do they do?

  1. Arteries carry blood away from the heart

  2. Capillaries exchange nutrients and oxygen with tissues

  3. Veins carry blood back to the heart
• What is the function and structure of Arteries?

  • Carry blood directly from the heart
  • Blood inside is at high pressures
  • Have thick layers of muscle and elastic tissue to be strong and elastic
  • Have small lumen
• What is the structure and function of Capillaries?

  • Very small vessels that come into close contact with cells
  • Walls are only one cell thick and permeable
  • Total cross-sectional area is much higher than arteries, so blood flows more slowly
  • Have a very small lumen-
• What is the function and structure of Vein?

  • Relatively large vessels with the biggest lumens
  • Walls are thin with small layers of elastic fibres and smooth muscle
  • Have valves to prevent backwards blood flow
• How do you Calculate rate of blood flow?

  Divide volume of blood by time taken