cardiac cycle

• what is the cardiac cycle ? 


  the sequence of events that occurs when the heart beats
• what are the 3 phases of the cardiac cycle ?


  diastole phase

  Atrial systole

  Ventricular systole
• diastole phase

  •  the ventricular muscles relax, and the atria fill with blood
• Atrial systole-


  the atria contract and force blood into the ventricles
• Ventricular systole-


  ventricles contract and force blood into the arteries.
• how does the heart beat ?

  -The SA node generates the impulse to contract

  The AV node slows down the impulse to allow the heart chambers to fill with blood

  •The nerve impulse is then carried down the bundle of His.

  •Then to the Purkinje fibres that branch out across the heart, to make the whole heart contract in rhythm.
• what does SA stand for ?


  sino-atrial node
• what does AV stand for ?


  atrio-ventricular
• 3 main blood vessels ?

  ØArteries

  ØVeins

  ØCapillaries
• arteries

  • carry blood away from the heart
  • most carrier oxygenated blood
  • have thick walls and small lumen
• veins

  • carry blood to the heart
  • most carry deoxygenated blood
  • have valves
  • thinner walls and large lumen
• capillaries

  • huge network of tiny vessels linking arteries and veins
  • narrow - one red blood cell wide
  • very thin walls to allow diffusion
• what blood does the pulmonary artery carry ?


  deoxygenated blood away from the heart
• what blood does the pulmonary vein carry ? 


  oxygenated blood away to the heart
• where do you measure a mammals pulse ?

  on the femoral artery

  • located on the inside of the hind back legs
• when does an animals heart rate change ?

  • excited
  • exercising
  • frightened