a. signals from SA node rushes to AV node because, the rate at which these SA node cells send out electrical signals determine the rate of entire heart beat.The impulses in AV node are slowed because this allows the atria to contract a fraction of second before the ventricles
b.there are 3 internodal pathways
2. middle
3. posterior
In discussing the anatomy of the heart and the sequence and timing of cardiac excitation in...
You are studying the heart of a strange newly-discovered primate species. Its basic structure is like that of the human heart, but the timing of the wave of excitation which emanates from the SA-node and spreads throughout the atria and ventricles are quite different. The figure below shows the time of arrival of the wave at various points in the heart relative to its generation at the SA-node. Cardiac action potentials were recorded at different points in the atrial and...