Draw a standard ECG and explain the different segments in it .

Explanation

ECG has 5 waves or deflections which are convertionally designated as PQRST. The five wave has a horizontal part in the beginning as well as inside. It is called isoportential or baseline. PR, and T waves lir above the hoizontal line. They are called positive waves. Q , and S wave lie below the horizontal line, and are therefore called negative waves. P represents the development of action potential at the sinoatrial node, and the spread of impulse throughout the atria. The atrial muscles become depolarized . After a fraction of a second, the next complex of QRS begins with a small downward or negative reflection of Q . QRS represents depolarisation of atrial muscles and depolarisation of ventricular muscles. It different components are PQ, QR and RS. PQ indicates contraction of atria. QR provides information about spread of cardiac impulse from SA node to AV node. RS gives information about pread of impulse from AV node to Purkinje fibers, and ventricular depolarization . It initiates contraction of ventricles. Ventricular contraction continues during ST part . it is followed by the relaxation of ventricules and development of the repolarisation of the repolarisation wave.