The electrical impulse is delayed in the AV node before propagating to the AV bundle (of His). During this delay the ___ contract.

During this delay, the atria contract, ensuring that blood is pushed into the ventricles before they begin to contract. This clever timing mechanism is crucial for efficient heart function, as it allows the ventricles to fill completely with blood before they pump it out to the lungs and the rest of the body. This electrical delay in the heart's conduction system is a fantastic example of nature's engineering. It highlights how intricately connected our bodily systems are—like a well-tuned orchestra! If the timing were even slightly off, it could lead to less effective heartbeats and, consequently, reduced blood circulation.