Final answer:
The heart's electrical and mechanical relationship begins with the signal from the SA node and involves the atria, ventricles, and various electrical pathways. The ANS plays a role in regulating cardiovascular activity.
Step-by-step explanation:
The heart's electrical and mechanical relationship begins with the signal from the sinoatrial (SA) node, which is located near the wall of the right atrium. Electrical charges spontaneously pulse from the SA node, causing the two atria to contract.
Next, the electrical signal reaches the atrioventricular (AV) node, located between the right atrium and right ventricle. Here, the signal pauses before spreading to the walls of the ventricles.
The electrical impulse then enters the bundle of His, travels through the bundle branches and Purkinje fibers, and finally reaches the ventricular myocardium. This leads to the contraction of the ventricles.
The autonomic nervous system (ANS) plays a role in cardiovascular activity by regulating the heart rate and force of contractions. It consists of two divisions: the sympathetic division, which increases heart rate and contractility, and the parasympathetic division, which decreases heart rate.