BIOC34H3 Lecture 3: Lecture 3 Notes
Document Summary
Lecture 3: the electrocardiogram (part ii), the electrical axis of the heart, and the cardiac cycle. The two branch bundles (left and right), take the waves of depolarization down from av node, down to either side of the heart until they reach purkinje fibers. It is possible for conduction to be slowed in either branch, creating a right or left branch bundle block. Ecg traces created by this condition are strange - the lines are "m" shaped as one branch bundle depolarizes before the other. A consequence is that ventricles will not contract simultaneously; instead, the ventricle with the block will contract after the ventricle that does not have a blockage. A common form of arrhythmia is heart flutter. Fibrillation is less common but more serious particularly in ventricles. Flutter and fibrillation can occur in atria or ventricles. Rapid rates of electrical excitation and contraction in either atria or ventricles can produce these conditions.