The intrinsic ability is cardiac muscle to generate action potentials (APs) rhythmically is achieved by the normal pace maker, sino-atrial node(S-A node). The S-A node is part of the special excitatory and conductive system of the cardiac muscle. With the help of a diagram, describe this conductive system how the AP spread throughout the muscle.
The conductive system of the cardiac muscle is composed of several structures that help in the spread of action potentials (APs) throughout the muscle. One of the key components of this system is the sino-atrial node (S-A node), which acts as the natural pacemaker for the heart.
Here is a diagram that shows the conductive system and the spread of APs in the cardiac muscle:
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S-A node --> Internodal pathways --> Atrioventricular node (A-V node) --> Bundle of His --> Bundle branches --> Purkinje fibers
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1. Sino-atrial node (S-A node): This is the starting point of the conduction system and is located in the upper part of the right atrium near the opening of the superior vena cava. The S-A node generates electrical impulses, leading to the initiation of action potentials.
2. Internodal pathways: These pathways are specialized cardiac muscle fibers that help in the transmission of action potentials from the S-A node to the atria. They ensure that the electrical signal is spread efficiently throughout both atria.
3. Atrioventricular node (A-V node): Located at the base of the right atrium near the atrial septum, the A-V node acts as a gateway for the electrical signals to move from the atria to the ventricles. It delays the conduction slightly, allowing for proper blood flow and coordination between the atria and ventricles.
4. Bundle of His: After passing through the A-V node, the action potentials travel down the interventricular septum through the bundle of His. This bundle is composed of specialized conductive fibers that quickly transmit the electrical signals to the ventricles.
5. Bundle branches: The bundle of His divides into left and right bundle branches, which extend down the interventricular septum and further distribute the electrical signals to the respective ventricles.
6. Purkinje fibers: These fine, terminal fibers extend from the bundle branches and spread throughout the ventricles, ensuring synchronized and coordinated contraction of the ventricular muscle.
Overall, this conductive system efficiently spreads action potentials from the S-A node to the rest of the cardiac muscle, allowing for rhythmic contractions and the pumping of blood.