Description: Segment 1 The heart is shown beating in the chest cavity. Its heart rate is then decreased by stimulating the vagus nerve with an electrode. An illustration shows the parts of the heart, and the intertitles describe what happens when the heart is stimulated electrically. An animation shows the conduction of the electrical pulse through the heart. Time start: 00:00:00:00 Time end: 00:04:43:12 Length: 00:04:43:12 Segment 2 An animation continues to show the electrical pulse being conducted through the heart, and the intertitles describe the areas that it passes through. An animation shows the action of the chambers of the heart during electrical stimulation. A graph with explanatory labels shows the changes in the beating heart. The heart's action and electrocardiographic tracing are shown simultaneously on a diagram. Time start: 00:04:43:12 Time end: 00:09:26:14 Length: 00:04:43:02