Heart Activity Flashcards
What 5 components make up the cardiac conduction system?
1) sinoatrial node
2) atrioventricular node
3) bundle of his
4) left and right bundle branches
5) purkinje fibres
Briefly describe the cardiac conduction system…
1) SAN receives electrical impulse causing rhythmic contraction of the heart (it is the intrinsic pacemaker)
2) impulse spreads over the atrial muscle- atrial contraction
3) impulse also conducted to AVN
4) AVN conducts electrical impulse to ventricular muscles via bundle of his, bundle branches and purkinje fibres
Define systole and diastole…
Systole- period of contraction
Diastole- period of relaxation
What is atrial systole?
Contraction of the head muscle of the left and right atria (at once)
What is ventricular systole?
Period where the left and right ventricles contract and eject blood into the aorta/pulmonary artery
What is diastole? (During cardiac cycle)
Atria and ventricles relaxed
Myocardium recovering
Blood is passively flowing throughout the heart
What is an electrocardiogram?
Non-invasive trans-thoracic graphic
Records electrical activity of the heart overtime
What is a sinus rhythm?
Normal rhythm of the heart
What is a P wave?
Caused by depolarisation of atrial muscles (caused by electrical impulse from SAN over left/right atria
What is the QRS complex?
Caused by depolarisation of the ventricular muscles
Electrical impulses from AVN spread to left/right ventricles via bundle of his/branches and purkinje fibres
What is the T wave?
Ventricular repolarisation
Immediate before diastole
What is the PR interval?
Time from onset of atrial activation to onset of ventricular activation
What does the ST segment represent?
Time during which ventricles are ejecting blood
