Circulatory System

• When blood reaches body cells oxygen diffuses out of the red blood cells and into the body cells
• When blood reaches body cells carbon dioxide diffuses out of the body cells and into the red blood cells
• The heart is an organ that pumps blood around the body in a double circulatory system
• The right ventricle of the heart pumps blood to the lungs where gas exchange takes place
• The left ventricle of the heart pumps blood around the rest of the body
• The natural resting heart rate is controlled by a group of cells located in the right atrium that act as a pacemaker
• Artificial pacemakers are electrical devices used to correct irregularities in the heart rate
• The three types of blood vessel are

  • Arteries
  • Veins
  • Capillary
• Arteries carry blood away from the heart
• Veins carry blood to the heart
• Capillaries are often used to exchange substances between the blood and the tissues
• Arteries have strong elastic walls because the blood is under high pressure
• The veins contain low pressure blood so they do not require thick walls
• Veins have a large lumen to help the blood flow despite the low pressure
• Veins have valves to prevent backflow
• Capillaries are have a thin permeable wall that is only one cell thick to increase the rate of diffusion
• Capillaries carry blood very close to every cell in the body to exchange substances
• The heart has valves to prevent backflow
• 1. Vena cava
  2. Right atrium
  3. Valve
  4. .
  5. Right ventricle
  6. Pulmonary artery
  7. Aorta
  8. Pulmonary vein
  9. Left atrium
  10. Valve
  11. Left ventricle

  
• Blood is a tissue consisting of plasma, in which the red blood cells, white blood cells and platelets are suspended
• Red blood cells carry oxygen from the lungs to body cells
• Red blood cells are biconcave which gives a large surface area for absorbing oxygen
• Red blood cells do not have a nucleus to allow more room for caring oxygen
• Red blood cells contain a red pigment called haemoglobin which binds together with oxygen at the lungs and separates to release oxygen to the body
• White blood cells defend against infection
• White blood cells can carry out phagocytosis, produce antibodies and antitoxins
• Platelets help blood clot and form scabs
• Platelets are small fragments of cells
• Plasma carries

  • Red and white blood cells
  • Platelets
  • Carbon dioxide
  • Nutrients like glucose and amino acids
  • Urea
  • Hormones
  • Proteins
  • Antibodies and antitoxins
• The left side of the heart has a thicker muscle wall than the right side of the heart to pump blood to the whole body