circularaty system

• circulatory system is made up of heart, blood and blood vessels
• right ventricle pumps deoxygnated blood to the lungs to take in oxygen . the blood then returns to the heart
• the left ventricle pumps oxygnated blood around all the organs of the body. the blood gives up its oxygen at the body cells and the deoxygnated blood returns to the heart to be pumped out to the lungs again
• the heart contracts to pump blood around the body
• heart is a pumping organ that keeps the blood flowing around the body. the walls of the heart are mostly made up of muscle tissues
• the heart has valves to make sure that blood flows in the right direction and to prevent backflow
• hearts 4 chambers

  • right atrium
  • right ventricle
  • left atrium
  • left ventricle
• blood flow in heart

  1.blood flows into the 2 atria through the vena cava and the pulmary vein
• blood flow in heart

  2.the atria contract, pushing the blood into the ventricles
• blood flow in heart

  3.the ventricles contract, forcing the blood into the pulmonary artery and the aorta ad our of the heart
• blood flow in heart

  4.the blood then flows to the organs through the arteries and returns through the veins
• blood flow in heart

  5.the atria fill again and the whole cycle starts over
• the heart also needs its own supply of oxygenated blood. Arteries called the 'CORONARY ARTERIES' branch off the aorta and surround the heart, making sure the heart gets all the oxygnated blood it needs
• heart diagram

  
• heart has a pacemaker
• resting heart rate is controlles by a group of cells in the right atrium wall that acts as a pacemaker. these cells produce a small ellectric impulse which spreads to the surrounding muscle cells, causing them to contract
• an artificial pacemaker is often used to control the heartbeat if the natural pacemaker cells dont work properly. its a little device thats implanted under the skin and has a wire going to the heart. it produces an electric current to keep the heart beating regulary
• arteries (carry blood away from heart)

  pumps the blood at a high pressure so the artery walls are strong and elastic

  walls are thick that contain thick layers of muscle to make them strong and elastic fibres to allow tjem to stretch and spring back
• capillaries (involved in exchange of materials at the tissues)

  very tiny

  have permeable walls so substances can diffuse in and out

  supply food and oxygen, and take away wastes like CO2

  one ceel thick so increases rate of difussion
• Veins (take blood back to heart)

  blood is at low pressure so walls dont need to be very thick

  have a bigger lumen than arteries to help blood flow despite lower pressure

  have valves to keep blood flowing in one direction
• red blood cells carry oxygen


  shape is biconcavr disc to give large surface area for abosorbing oxygen

  no nucleus allowing more room for oxygen

  has haemoglobin (a protein to give energy) that binds to oxygen to make oxyhaemoglobin
• white blood cells (defend against infection)
• platelets help blood clot

  small fragaments of cells that have no nucleus

  help to make scab so blood doesnt pour out and to stop microorganisms getting in

  lack of platelets can cause excessive bleeding and bruising
• plasma is the liquid that carries everything in blood


  contains red and white blood cells and platelets

  has nutrients like glucose and amino acids

  CO2 from organs to lungs

  Urea from liver to kidneys

  Hormones

  proteins

  Antibodies&Antitoxins