Circulatory system

• The circulatory system is made up of the heart, blood vessels (arteries, veins & capillaries) and blood.
• double circulatory system


  blood is pumped from the heart to the lungs to become oxygenated.

  blood is then pumped from the lungs back to the heart.

  then the blood is pumped from the heart to the organs.
• there are four chambers in the heart

  • right atrium
  • right ventricle
  • left atrium
  • left ventricle

  
• valves are in the heart to prevent back flow of blood so it flows in the right direction
• right side of the heart

  deoxygenated blood enters through the vena cava into the right atrium

  blood travels from the right atrium to the right ventricle

  it then exits the heart through the pulmonary artery to go to the lungs
• left side of the heart

  oxygenated blood enters through the pulmonary vein into the left atrium

  blood travels from the left atrium to the left ventricle

  it then exits the heart through the aorta to go to the body
• the heart also needs a supply of oxygenated blood

  coronary arteries branch off the aorta and surround the heart so it gets all the oxygenated blood it needs.
• pacemaker


  controls your resting heart rate
• if your pacemaker isn't working doctors can install an artificial pacemaker
• artificial pacemaker


  a small electrical device that produces an electrical current to keep the heart beating regularly
• types of blood vessels

  • arteries
  • capillaries
  • veins
• arteries 


  carry high-pressure oxygenated (except pulmonary) blood away from the heart to the body. thick walls
• capillaries


  they carry blood close to every cell to exchange substances with them.

  they have permeable, thin walls to allow diffusion of substances such as CO2 and oxygen
• veins


  thin walls as there is low blood pressure.

  they have valves so blood flows the right way
• plasma


  liquid part of the blood
• parts of the blood

  • plasma
  • red blood cells
  • white blood cells
  • platelets
• blood plasma transports

  • soluble digestion products
  • carbon dioxide
  • urea
• red blood cells transport oxygen from the lungs to the body cells
• red blood cell adaptations

  • has haemoglobin to carry oxygen
  • have no nucleus - more room for haemoglobin
  • biconcave shape - red blood cells larger surface area for faster diffusion
• white blood cell 


  form part of the immune system to defend against infection
• pacemaker cells are found in the right atrium