heart and blood vessels

• Double circulatory system

  Blood passes through the heart twice in one complete circuit of the body e.g. in a human
• Top chambers of the heart

  atria (atrium)
• Bottom chambers of the heart

  ventricles
• where does the right side of the heart pump blood to?

  deoxygenated blood to the lungs
• where does the left side of the heart pump blood to?

  rest of the body to provide oxygen and nutrients
• pacemaker


  A group of cells located in the right atrium that sends out signals that make the heart muscle contract and that regulates heart rate.
• where in the heart is the pacemaker?

  right atrium
• how can we treat a faulty pacemaker?

  artificial pacemaker
• what does a valve do?

  prevents backflow of blood
• Why does the left ventricle have a thicker wall than the right ventricle?

  It has to pump blood all around the body so it needs extra muscle
• Which blood vessels carry blood away from the heart?

  arteries
• which blood vessels carry blood to the heart?

  veins
• What do the coronary arteries do?

  Supply oxygenated blood to the heart muscle
• Adaptations of arteries

  Thick, elastic walls to withstand pressure.
• Function of veins

  carry low pressure blood to the heart
• How are veins adapted to their function?

  - the walls are not thick as blood is not carried at a low pressure

  - they have a big lumen to help blood flow

  - they have valves to keep blood flowing in the right direction
• What is the function of capillaries?

  To exchange substances with all cells
• Capillary adaptations

  thin walls (one cell thick) minimise diffusion distance

  large numbers of capillaries, to increase surface area for exchange

  found very near cells in exchange tissue - short diffusion pathway

  very small, red blood cell barely fits, so flows through slowly all the substances diffuse into body cells
• How to calculate blood flow rate?

  vol of blood/ mins