How the cardiac cycle is produced by electrical impulses in the heart

Summary

This animation explains the cardiac cycle, beginning with an electrical impulse from the sinoatrial node, which travels through the atria, causing them to contract and pump blood into the ventricles. The impulse is delayed at the atrioventricular node to allow the ventricles to fill with blood. It then travels along the bundle of His, spreading through the ventricles, prompting a coordinated contraction that pumps blood to the lungs and body. The video also highlights atrial fibrillation, where disorganized electrical activity disrupts the heart's rhythm and pumping efficiency.

Takeaways

• 😀 The cardiac cycle begins when an electrical impulse or action potential is generated by the sinoatrial node.
• 😀 The electrical impulse travels along specialized conducting fibers in the walls of the atria, causing them to contract and pump blood into the ventricles.
• 😀 In a normal heart, the electrical impulse travels rapidly, ensuring that all muscle cells in the atria contract together for coordinated pumping.
• 😀 The impulse reaches the atrioventricular node, where it is slightly delayed to allow the ventricles to relax and fill with blood before contracting.
• 😀 The impulse continues through the bundle of His, dividing into the left and right bundle branches located in the interventricular septum.
• 😀 From the bundle branches, the impulse spreads to the inner walls of the ventricles via specialized conducting fibers called Purkinje fibers.
• 😀 The impulse then travels upward along the outer walls of the ventricles towards the atria.
• 😀 The rapid and controlled spread of the electrical impulse through the ventricles causes them to contract together and pump blood efficiently to the lungs and body.
• 😀 Atrial fibrillation occurs when the electrical activity in the atria becomes disorganized, disrupting the pumping function of the atria.
• 😀 Atrial fibrillation leads to a loss of rhythm and efficiency in the entire heart, affecting overall heart function.

Q & A

What is the starting point of the cardiac cycle?

The cardiac cycle starts when an electrical impulse or action potential is generated by the sinoatrial (SA) node.

How does the electrical impulse travel through the heart?

The electrical impulse travels along specialized conducting fibers in the walls of the atria, stimulating the atria to contract and pump blood into the ventricles.

What happens during the contraction of the atria?

The atria contract and pump blood into the ventricles, and the muscle cells in the atria contract together, producing a coordinated pumping action.

Why is there a slight delay at the atrioventricular (AV) node?

The impulse is delayed slightly at the AV node to allow the ventricles to relax and fill with blood before they contract.

What role does the bundle of His play in the cardiac cycle?

The impulse travels along the bundle of His, where the conducting pathways divide into the left and right bundle branches in the interventricular septum.

How does the impulse spread to the ventricles?

From the bundle branches, the impulse spreads into the inner walls of the ventricles through specialized conducting fibers called Purkinje fibers.

What happens after the impulse reaches the outer walls of the ventricles?

The impulse travels up the outer walls of the ventricles towards the atria, stimulating the muscle cells in the ventricles to contract together and pump blood efficiently to the lungs and body.

How does atrial fibrillation affect the heart's function?

During atrial fibrillation, the electrical activity of the atria becomes disorganized, leading to the loss of the atria's pumping function, disturbing the rhythm and efficiency of the entire heart.

Why is the coordination of electrical impulses important in the cardiac cycle?

Coordinated electrical impulses ensure that the atria and ventricles contract together, allowing for efficient blood pumping to the lungs and body.

What is the role of the specialized conducting fibers in the heart?

Specialized conducting fibers, such as Purkinje fibers, help spread the electrical impulse to ensure the ventricles contract in a coordinated manner for efficient blood pumping.