The heart and blood vessels

• Function of the heart

  The heart pumps blood around the body in a double circulatory system. There are two
• Deoxygenated blood 


  Flows into the right atrium and then into the right ventricle.
• Arteries

  Carry blood away from the heart (except pulmonary arter) have thick muscular walls, contain blood under high pressur.
• Veins 


  carry blood to the heart (except pulmonary vein) have thin walls, contain blood under low pressure, have valves to prevent the blood flowing backwards.
• Capillaries 


  1 cell thick for effective diffusion, connect arteries to veins.
• Plasma 


  Contains dissolved substances and transports them around the body e.g. glucose and carbon dioxid.
• The heart 


  Is an organ that pumps blood around the body in a double circulatory syste.
• The right ventricle 


  Pumps blood to the lungs where gas exchange takes place.
• The left ventricle 


  Pumps blood around the whole body.
• Heart rate 


  The natural resting heart rate is cont by a group of cells located in the right atrium that act as a place marker.
• Lungs 


  .alveoli have a large surface area and are one cell thick to allow fast gas exchange.

  .the alveoli are surrounded by a network of capillaries.
• Blood 


  Blood is a tissue which is made up of plasma, red blood cells, white blood cells.
• Red blood cells 


  .flattened disc shape-large surface area for gas exchange.

  .contains haemoglobin.

  .no nucleus so the cell can hold more haemoglobin.
• White blood cells 


  Help to protect the body against infection.
• Platelets 


  Help the blood to clot forming a scab.
• Treating CHD 


  Stents
• stents 


  A stent is a device used to keep coronary arteries open
• Stents 


  Made out of a metal mesh and are inserted into clogged arteries
• Statins 


  Statins a class of drugs used to lower cholesterol levels in the blood
• Advantages of statins 


  decrease the chances of stroke and heart disease