The intrinsic ability of cardiac muscle to generate action potentials(APs) rhythmically is achieved by the normal pace maker, the sino-atrial node(S-A node). The S-A node is part of the special excitatory and conductive system of cardiac muscle. With the help of a diagram, describe this conductive system how the AP spreads throughout the muscle
Unfortunately, as a text-based AI model, I am unable to provide diagrams. However, I can still describe the conductive system of cardiac muscle and how action potentials (APs) spread throughout the muscle.
The conductive system of the heart consists of specialized cells that are responsible for initiating and coordinating the electrical activity of the cardiac muscle. This system includes the sinoatrial node (S-A node), atrioventricular node (A-V node), bundle of His, bundle branches, and Purkinje fibers.
1. Sinoatrial node (S-A node): The S-A node is the primary pacemaker of the heart located in the right atrium near the opening of the superior vena cava. It generates spontaneous APs at regular intervals, setting the rhythm for the heart. These APs spread throughout the atria, causing atrial muscle contraction.
2. Atrioventricular node (A-V node): The APs generated by the S-A node travel through specialized conducting cells called internodal pathways to reach the A-V node, located in the lower part of the right atrium near the atrioventricular septum. The A-V node acts as a delay, allowing time for the atria to contract fully before transmitting the APs to the ventricles.
3. Bundle of His: After the APs pass through the A-V node, they enter the bundle of His, which is a pathway of specialized conducting fibers. The bundle of His extends into the interventricular septum, which separates the left and right ventricles.
4. Bundle Branches: The bundle of His divides into two branches, known as the right and left bundle branches. These branches extend along the interventricular septum, eventually reaching the respective ventricles.
5. Purkinje fibers: The bundle branches further divide into numerous Purkinje fibers. These fibers rapidly conduct the APs to the muscular walls of the ventricles, ensuring synchronous and coordinated contraction of the cardiac muscle.
By following this specialized excitation pathway, the APs generated by the S-A node spread efficiently through the atria, A-V node, bundle of His, bundle branches, and Purkinje fibers, ultimately causing the coordinated contraction of the cardiac muscle and proper pumping of blood.