The electrical impulse is delayed in the AV node before propagating to the AV bundle (of His). During this delay the ______Blank contract. Multiple Choice right atrium and right ventricle right atrium and left atrium left ventricle and aorta left atrium and left ventricle
The correct answer and explanation is:
The correct answer is: right atrium and left atrium
Explanation:
The heart’s electrical conduction system controls the sequence of heart muscle contractions, ensuring efficient pumping of blood. The sinoatrial (SA) node, located in the right atrium, initiates the electrical impulse that causes the atria to contract.
Once the electrical impulse begins at the SA node, it spreads through the atria, causing both the right atrium and left atrium to contract simultaneously. This atrial contraction pushes blood into the ventricles.
The impulse then reaches the atrioventricular (AV) node, which is situated at the junction between the atria and ventricles. The AV node delays the electrical impulse slightly before passing it on to the AV bundle (also called the bundle of His). This delay is crucial because it allows the atria time to fully contract and empty their blood into the ventricles before the ventricles begin to contract.
During the AV node delay, only the atria (both right and left) contract; the ventricles remain relaxed and filling with blood. After the delay, the impulse moves quickly through the AV bundle, bundle branches, and Purkinje fibers to stimulate ventricular contraction.
Summary:
- SA node fires → electrical impulse spreads through right and left atria, causing their contraction.
- Impulse reaches AV node → delay occurs to allow atrial contraction to complete.
- Then impulse propagates to ventricles for their contraction.
Therefore, the correct choice is right atrium and left atrium contract during the AV node delay.