specification

• red blood cells – contain haemoglobin for transport of oxygen
• platelets – clotting
• plasma – transport of carbon dioxide, soluble food, urea, hormones and the distribution of heat
• white blood cells - defence against disease
• the heart is made of muscle, which contracts to pump blood around the body
• the coronary vessels supply the heart muscle with blood
• flow of blood to the organs through arteries and return to the heart through veins
• heart diagram -

  A) semilunar valves

  B) left atrium

  C) right atrium

  D) bicuspid valve

  E) tricuspid valve

  F) septum

  G) right ventricle

  H) left ventricle

  
• Arteries have thick muscular walls to resist the high blood pressure
• The hearts pulse pushes the blood through the artery blood vessel
• Veins have thinner walls than the artery because they do not need to resist high blood pressure - this allows muscles around the vessel to squeeze the blood and cause it to move
• veins have valves to ensure the movement of blood only towards to the heart
• veins have large lumen to increase the rate of flow of the blood
• Capillary walls are only one cell wall thick to allow easy passage of materials in and out by diffusion
• blood flow in the capillary is very slow to allow time for materials to be exchanged
• Capillaries have extensive networks in each organ so every cell is near a capillary - more materials can be exchanged
• a double circulatory system: involving one system for the lungs – pulmonary and one for the other organs of the body – systemic
• in the organs, blood flows through very small blood vessels called capillaries; substances needed by cells pass/diffuse out of the blood to the tissues, and substances produced by the cells pass/diffuse into the blood, through the walls of the capillaries
• the thin walls of the capillaries are an advantage for diffusion;
• capillaries form extensive networks so that every cell is near to a capillary carrying blood
• artery and vein diagram -

  A) connective tissue

  B) muscle and elastic fibres

  C) inner lining - endotheleum

  D) lumen

  
• cardiovascular diseases can be caused by -

  1. high levels of fat and salt in the diet
  2. smoking
  3. genetic factors
  4. lack of exercise
• Atherosclerosis is the build-up of fatty material (such as cholesterol), fibrous material and calcium). The build-up forms an atheroma (degeneration of the walls of the arteries) under the endothelium (cells that line the interior surface of blood vessels).
• As the atheroma continues to build up it causes a number of things to happen:

  • the artery loses its elasticity
  • the blockage restricts blood flow due to the decreased diameter of the lumen
  • the restricted blood flow increases blood pressure
• Atherosclerosis can lead to various cardiovascular diseases such as angina, heart attack, stroke, and peripheral vascular disease (PVD).
• CVD is usually linked to a process called atherosclerosis. This is the build up of a substance called plaque in the walls of the arteries.
• Statins, a daily medication to control blood cholesterol levels, but may cause side effects.
• Angioplasty, surgery to place a small balloon in a blood vessel, which is inflated to remove a blockage. This results in improved blood flow e.g. in coronary vessels, but sometimes is only a temporary remedy.
• Changes to diet/ lifestyle. These include stopping smoking, taking up regular exercise, eating more healthy food. These can reduce risk and lower blood pressure. However, a high level of self-discipline is needed to maintain these long-term changes