1. key components of the cardiac conduction system:
- the depolarisation process which is started from the
sino-atrial node and then transfer to the atrio-ventricular node
through the atrial mwall.
- before depolarisation of the ventricle there is a delay in
transmitting conduction is known as delay in A-V node.
- then the conduction transmit to the ventricle for ventricular
depolarisation through bundle if his and then to left bundle branch
(LBB) and right bundle branch (RBB).
2.sequence of electrical cardiac event:
the sequence of electrical cardiac nevents are:
- atrial systole: is a impulse generated from SAN and last for
0.1 sec. here atria muscle contracts and its pressure
increases.
- ventricular systole: is a process of excitation where ventricle
contract and ventricular pressure increases. duration is 0.3 sec.
here we can listen the first heart sound.
- ventricular diastole: at the end of ventricular systole the
ventricular pressure is drops and arterial pressure maintained and
immediately it increases and closed the semilunar valve which
creates the second heart sound. it lasts for 0.5sec.
- arterial diastole: here the atrial muscle relax and pressure
gradually increases. it lasts for 0.7sec.
3. EKG waves, complexes and intervals:
- P-waves: is formed due to atrial depolarisation due to the
transmission of impulse from sino-atrial node to atrial
muscle.
- P-R interval: is formed due to transmission of impulse to
ventricles. that delay in contraction of ventricle represent p-r
segment.
- QRS complex: is formed due to the ventricular
depolarisation.
- S-T segment: is formed due to the atrial repolarisation or the
time taking for relax of atrial muscle.
- T-wave is formed due to ventricular repolarisation.
- U-wave: sometime duet o hyper kalemia there is formation of
U-wave. which is very rare.