the circulatory system

• 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
• HeartConsists..


  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
• Arteriesstructure


  • 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 Structure


  • Very small vessels that come into close contact with cells
  • Walls are only one cell thick and permeable
  • Total cross-sectional area is much larger than arteries, so blood flows more slowly
• Veins Structure


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


  Divide volume of blood by time taken
• 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 Adaptations


  • 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
• White blood cells


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


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


  Have a nucleus, unlike red blood cells
• Platelets


  Small fragments of cells that float in the blood and rush to wounds to help clot the blood and stop bleeding
• Plasma


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

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


  Giving a person real blood that has been donated, contains red blood cells which is key for surviving blood loss
• Physical and chemical barriers


  Stop pathogens from getting into the body
• Immune system


  Destroys pathogens that do make it into the body
• Skin


  • Acts as a physical barrier that pathogens can't get through
  • Secretes oils and antimicrobial substances that can kill pathogens
• Nose


  Has hairs and mucus that can trap pathogens and particles in the air
• Trachea and esophagus


  Only two tubes leaving the throat that pathogens can enter
• Trachea, bronchi, and bronchioles


  1. Covered in mucus that traps particles

  2. Lined with cilia that move mucus and trapped particles up to the throat to be swallowed
• Stomach acid


  Hydrochloric acid that kills most pathogens
• White blood cells function


  Patrol the body and have three important functions: phagocytosis, producing antitoxins, and producing antibodies
• Phagocytosis


  Process where white blood cells consume and destroy pathogens