Cardiac impulses pass from the atria to the ventricles primarily via which structure?

The cardiac impulses travel from the atria to the ventricles primarily through the Bundle of His, also known as the atrioventricular (AV) bundle. This structure is crucial in the conduction system of the heart because it provides the only electrical connection between the atria and ventricles. The atria contract first, allowing blood to flow into the ventricles, and then the Bundle of His facilitates the coordinated contraction of the ventricles by conducting the impulse down to the right and left bundle branches, which further transmit the signals to the Purkinje fibers and ultimately stimulate ventricular contraction.

The Bundle of His is located at the junction of the atria and ventricles, ensuring that the timing of the electrical impulses is precise and allows for efficient pumping of blood. This is essential for maintaining proper cardiac function and synchronizing the heart's rhythm.

Other structures like the bundle branches and Purkinje fibers play a role in further disseminating the impulse after it has passed through the Bundle of His, and the SA node is responsible for initiating the heartbeat. However, they do not primarily facilitate the transmission from the atria to the ventricles in the same direct manner as the Bundle of His.