Circulatory system

• What is the Circulatory system?

  An example of an organ system, its role is to transport oxygen and nutrients to the body's tissues
• What are the 3 main components in the 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, 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
• The heart acts as the pump for the circulatory system
• Blood vessels


  1. Arteries carry blood away from the heart

  2. Capillaries exchange nutrients and oxygen with tissues

  3. Veins carry blood back to the heart
• 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
• 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
• Veins


  • Relatively large vessels with the biggest lumens
  • Walls are thin with small layers of elastic fibers and smooth muscle
  • Have valves to prevent backwards blood flow
• Calculating rate of blood flow


  Divide volume of blood by time taken
• 2500 ml of blood passes through the aorta in 8 minutes
• Main components of blood


  • Red blood cells
  • White blood cells
  • Platelets
  • Plasma
• Red blood cells


  Carry oxygen from the lungs to the body's tissues
• Red blood cells


  • Don't have a nucleus, which means more space for hemoglobin and oxygen
  • Shaped like a biconcave disc, which gives them a large surface area for absorbing oxygen
• Hemoglobin


  Red pigment in red blood cells that combines with oxygen to become oxyhemoglobin
• Oxygen transport by red blood cells


  1. Hemoglobin combines with oxygen to become oxyhemoglobin

  2. Oxyhemoglobin travels to tissues

  3. Oxyhemoglobin splits back into hemoglobin and oxygen

  4. Oxygen diffuses into tissues
• White blood cells


  Essential part of the immune system, defend against infection
• Functions of white blood cells


  • Phagocytosis (engulf and consume microorganisms)
  • Produce antibodies that bind to and help destroy pathogens
  • Produce antitoxins that neutralize toxins from pathogens
• White blood cells


  • Have a nucleus, unlike red blood cells
• Platelets


  Small fragments of cells that float in the blood and help stop bleeding by clotting
• Plasma


  Pale straw-colored liquid that makes up over half the blood's volume, carries nutrients, waste, hormones, antibodies, and other substances
• Most adults have about 5 liters of blood flowing through their circulatory system at any one time
• Artificial blood


  Blood substitute consisting of salt water, adds volume to the circulatory system but doesn't contain red blood cells so can only replace 1/3 of blood
• Blood transfusion


  Giving a person real blood donated by blood donors, contains red blood cells which is key for surviving blood loss