the heart and blood vessels

• what is the heart?

  an organ that pumps blood around the body in a double circulatory system
• what is the job of the heart?

  to pump blood around the body
• what are the atria separated by?

  valves
• what does the right ventricle do?

  pump blood to the lungs where gas exchange takes place
• what does the left ventricle do?

  pump blood around the rest of the body
• what does the vena cava do?

  it brings in deoxygenated blood from the body
• what happens at the pulmonary artery?

  the blood passes form the heart to the lungs in the pulmonary artery
• what happens at the pulmonary vein?

  oxygenated blood passes from the lungs to the heart in the pulmonary vein
• what happens at the aorta?

  oxygenated blood is pumped from the heart to the body in the aorta
• • first blood enters the left atrium and the right atrium
  • the atria now contract and the blood is forced into the ventricles
  • the ventricles now contract and force blood out of the heart
  • the valves stop the blood from flowing backwards into the atria when the ventricles contract
• • first blood enters the left atrium and the right atrium
  • the atria now contract and the blood is forced into the ventricles
  • the ventricles now contract and force blood out of the heart
  • the valves stop the blood from flowing backwards into the atria when h ventricles contract
• why does the left side of the heart have a thicker muscular wall than the right side?

  the left ventricle pumps blood around the entire body so it needs to provide a greater force, the right ventricle only pumps blood to the lungs
• what are the coronary arteries?

  they branch out of the aorta and spread out into the heart muscle
• what is the purpose of the coronary arteries?

  to provide oxygen to the muscle cels of the heart
• how is the natural resting heart rate controlled by?

  a group of cells located in the right atrium that act as a pacemaker
• what are artificial pacemakers?

  electrical devices used to correct irregularities in the heart rate
• what do arteries carry?

  very high pressure blood from the heart to the organs in the body
• what is 1 adaptation of arteries?

  arteries have very thick muscular walls

  this allow them to withstand the very high pressure of the blood
• what is another adaptation of arteries?

  arteries contain elastic fibres which stretch when the surge of blood passes through and then recoil in between surges which keeps the blood moving
• what happens when the blood passes through capillaries?

  substances such as glucose and oxygen diffuse from the blood to the cells
• what is 1 adaptation of capillaries?

  they have very thin walls, so the diffusion path is very short

  this allows substance to diffuse rapidly between the blood and the body cells
• what happens when the blood makes its way back to the heart in the veins?

  the blood travels slowly and at low pressure

  this means that it could stop or even go backwards
• what is 1 adaptation of veins?

  veins have a thin walls

  the blood pressure is low so the wall does not need to be thick
• what is another adaption of veins?

  veins contain valves (they stop blood flowing backwards) when the blood is flowing in the correct direction then the valves open to allow the blood to flow through
• what is the blood?

  a tissue consisting of plasma, in which the red blood cells, white blood cells and platelets are suspended
• what does the blood plasma transport?

  • soluble digestion products(such as glucose)from the small intestine to other organs carbon
  • carbon dioxide(produced by aerobic respiration) from the organs to the lungs to be breathed out
  • the waste-product urea from the liver to the kidneys to be excreted into urine
• what do red blood cells do?

  transport oxygen from the lungs to the body cells
• what are the 3 adaptations of red blood cells?

  • they contain the oxygen-carrying molecule haemoglobin
  • they have no nucleus, which means that they have more room for haemoglobin
  • they have a bioncave disk shape this shape gives the red blood cells a greater surface area so that oxygen diffuses in and out rapidly
• what are white blood cells?

  they form a part of the immune system e.g making antibodies
• what do white blood cells contain?

  contain a nucleus this contains DNA which encodes the instructions that the white blood cells need to do their job
• what are platelets?

  tiny fragments of cells
• what is the job of platelets?

  to help the blood clot
• what are cardiovascular diseases?

  diseases of the heart and blood vessels
• in coronary heart disease layered of fatty material build up inside the coronary arteries, narrowing them

  this reduces the flow of blood through the coronary arteries resulting in a lack of oxygen for the heart muscle
• what are statins?

  drugs which reduce the level of cholesterol in the blood

  this slows down the rate that fatty materials build up in the arteries
• what are advantages of statins?

  • stains have been proven to reduce the risk of coronary heart disease - this means that they are effective
• what are disadvantages of statins?

  • they have unwanted side effects (liver problems)
• what is a stent?

  stents are used to keep the coronary arteries open
• what is an advantage of using a stent?

  • the blood can flow normally though the artery
• what are disadvantages of using a stent?

  • a stent will not prevent other regions of the coronary arteries from narrowing
  • it does not treat the underlying causes of the disease