Depolarization and Repolarization Quiz

The correct sequence of ECG events is P wave, QRS complex, T wave. The P wave represents atrial depolarization, which is the electrical activity that causes the atria to contract. The QRS complex represents ventricular depolarization, which is the electrical activity that causes the ventricles to contract. The T wave represents ventricular repolarization, which is the electrical activity that allows the ventricles to relax and prepare for the next contraction. Therefore, the correct sequence of events is P wave, QRS complex, T wave.

The correct answer is Sino-atrial node. The Sino-atrial node is located in the right atrium of the heart and is responsible for initiating the electrical impulses that regulate the heart's rhythm. It acts as the heart's natural pacemaker, sending signals to the atria to contract and pump blood into the ventricles. The electrical current generated by the Sino-atrial node then spreads throughout the heart, coordinating the contraction and relaxation of the different chambers and ensuring an efficient pumping action.

Repolarization refers to the process in which fully depolarized cells make an effort to return to their resting state. During depolarization, the cell's membrane potential becomes more positive, while during repolarization, it becomes more negative again. Therefore, repolarization is the correct term to describe the phenomenon of cells returning to their resting state after depolarization.

The T wave on an electrocardiogram (ECG) represents the repolarization of the ventricles. During this phase of the cardiac cycle, the ventricles are resetting their electrical charge in preparation for the next heartbeat. The T wave is a small, rounded wave that follows the larger QRS complex on the ECG. It is important in assessing the overall health and function of the heart, as abnormalities in the T wave can indicate various cardiac conditions. The other options, repolarization of atria and none of the above, are incorrect as they do not accurately describe what the T wave represents.

The U wave is occasionally absent from an ECG. The U wave represents the repolarization of the Purkinje fibers in the ventricles. It is a small, rounded wave that follows the T wave. While it is not always present, its absence can be an indication of certain conditions such as hypokalemia or hypercalcemia.

In the process of ventricle depolarization, the electrical impulse is transmitted to the walls of the ventricles. This means that the electrical signal that initiates the contraction of the ventricles is received by the ventricle walls, causing them to contract and pump blood out of the heart.

ECG stands for Electro Cardio Gram. It is a medical test that records the electrical activity of the heart. This test is commonly used to detect and diagnose various heart conditions, such as arrhythmias, heart attacks, and heart disease. During an ECG, electrodes are placed on the skin to measure the electrical signals produced by the heart. These signals are then recorded and displayed as waves on a graph, providing valuable information about the heart's health and functioning.

Conductivity refers to a cell's ability to transmit an electrical impulse to another cell. In the context of the question, conductivity is the correct answer as it describes the capacity of a cardiac cell to send an electrical impulse to an additional cardiac cell. Conductivity is an essential property of cardiac cells that allows for the coordinated contraction of the heart muscle, ensuring proper functioning of the organ.

The AV node is responsible for controlling the heart rate by firing electrical signals between 40 and 60 times per minute. This node acts as a bridge between the atria and the ventricles, allowing for coordinated contractions and proper blood flow. The other options, such as the SV node and Purkinje fibers, do not regulate the heart rate in this specific range. Therefore, the correct answer is the AV node.

The tricuspid valve is responsible for controlling the flow of blood between the right atrium and right ventricle of the heart. If the tricuspid valve is harmed, it can lead to a condition called tricuspid valve regurgitation or tricuspid valve stenosis. This can result in blood flowing back into the right atrium instead of going to the lungs to get oxygenated, causing symptoms such as fatigue, shortness of breath, and fluid retention. In severe cases, it may require surgical intervention to repair or replace the damaged valve.