Circulatory system

• 3 components of the circulatory system are:

  • heart
  • blood vessels
  • blood
• the role of the circulatory system is to transport substances around the body via the blood.
• our circulatory system has two loops one that passes through the lungs and one that passes around the body.
• Because there are 2 loops we call it a double circulatory system.
• A double circulatory system is good as it allows the pressure in the blood to be increased again before being pumped around the body.
• the hearts role is to pump blood to the lungs and the body.
• The heart has 4 chambers:

  • Right atrium
  • right ventricle
  • left atrium
  • left ventricle
• The pulmonary artery carries blood from the heart to the lungs.
• The pulmonary vein carries blood away from the lungs.
• the right side of the heart pumps deoxygenated blood to the lungs.
• the pulmonary vein carries oxygenated blood to the left atrium.
• Vena cava - carries deoxygenated blood from the body to right atrium.
• Pulmonary artery carries deoxygenated blood from the right ventricle to the lungs.
• Pulmonary vein carries oxygenated blood from the lungs to the left atrium.
• Aorta carries oxygenated blood from the left ventricle to the body
• The left ventricle has thicker walls as it has to pump blood around the entire body.
• valves prevent the backflow of of blood.
• Right side of heart= tricuspid valve

  left side of heart= bicuspid valve
• Semi-lunar valves are the ones in between the ventricles and the arteries.
• The route blood takes as it passes around the body

  Vena cava -> right atrium -> right ventricle -> pulmonary artery -> lungs -> pulmonary vein -> left atrium -> left ventricle -> aorta -> body -> vena cava
• Coronary arteries supply the heart muscle with oxygenated blood.
• Approximate value of resting heart rate is 70bpm
• Heart rate is controlled by a group of cells in the right atrium which act as a pace maker. They release waves of electrical activity causing the heart muscle to contract rhythmically.
• The 3 main types of blood vessels are:

  • Arteries
  • capillaries
  • veins
• Arteries carry blood away from the heart
• Capillaries exchange substances with the cells of the body.
• Veins carry blood towards the heart.
• Veins have valves
• Arteries are adapted. they have:

  • Thick muscle layer
  • thick elastic layer
  • thick walls
• capillaries are adapted. they are:

  • one cell thick
  • permeable walls
  • narrow lumen
• Veins are adapted. they have:

  • wide lumen
  • valves
• rate of blood flow= vol of blood/time
• 4 components of blood:

  • red blood cells
  • white blood cells
  • platelets
  • plasma
• Plasma is yellow liquid that transports substances around the body
• Nutrients, waste products, antibodies and more are all dissolved in plasma.
• Red blood cells transport oxygen around the body.
• Red blood cells are adapted:

  • contain haemoglobin
  • biconcave shape
  • no nucleus
• white blood cells protect the body from invading pathogens.
• white blood cells are adapted:

  • some can produce antibodies
  • some can produce antitoxins
  • some can engulf and digest pathogens
• platelets are small cell fragments which help the blood clot