Cards (22)

  • The pulmonary circuit is the movement of blood between heart and lungs.
  • The systemic circuit is the movement of blood between heart and the rest of the body.
  • Sino-atrial node (SA node): located in the right atrial wall, the SA node initiates the cardiac cycle and generates the electrical impulse and fires it through the atria walls, causing them to contract.
  • Atrio-ventricular (AV node): collects the impulse and delays it for approximately 0.1 seconds to allow the atria to finish contracting. It then releases the impulse to the Bundle of His.
  • Bundle of His: located in the septum of the heart, the bundle of His splits the impulse in two spreading the impulse, to be distributed through each seperate ventricle.
  • Bundle Branches: these carry the impulse to the base of each ventricle.
  • Purkinje fibres: these distribute the impulse through the ventricle walls, causing them to contract.
  • There is a pause when no impulse happens where the heart walls relax.
  • Cardiac diastole is the relaxation of the atria and ventricles when the chambers fill with blood and the pressure increase opens the valves.
  • In cardiac diastole the atria relax, expanding in size, drawing blood into the atria which increases their pressure causing the AV valves to open and blood starts to passively enter the ventricles which are relaxed. Semi-lunar valves are forced open as blood builds up in the relaxed ventricles and blood starts to enter the aorta and pulmonary artery.
  • Cardiac systole is the contraction of the atria and ventricles when the chambers contract and blood is forced out.
  • In cardiac systole the atria contract (atrial systole), forcing blood into the ventricles. Then the ventricles contract (ventricular systole), forcibly ejecting blood into the aorta and pulmonary artery.
  • Heart rate is the number of times the heart beats per minute.
  • Stroke volume is the volume of blood ejected from the left ventricle per beat.
  • Cardiac output is the volume of blood ejected by the heart per minute.
  • Average resting values: Untrained
    Heart Rate: 70bpm
    Stroke Volume: 70ml
    Cardiac Output: 5l/min
  • Average resting values: Trained
    Heart Rate: 50bpm
    Stroke Volume: 100ml
    Cardiac Output: 5l/min
  • Average submaximal values: Untrained
    Heart Rate: 100bpm
    Stroke Volume: 100ml
    Cardiac Output: 10l/min
  • Average submaximal: Trained
    Heart Rate: 100bpm
    Stroke Volume: 200ml
    Cardiac Output: 20l/min
  • Average maximal values: untrained
    Heart rate: 220-age
    Stroke Volume: 100ml
    Cardiac Output: 20l/min
  • Average maximal values: Trained
    Heart Rate: 220-age
    Stroke Volume: 200ml
    Cardiac Output: 40l/min
  • Bradycardia: a resting heart rate below 60bpm